Peavey VTM-120 issue
adam79
Could it be that one of the fuses have blown? It has three of them, but
I'm not sure what they're all for. Any guesses?
Thanks,
-Adam
Fred
Morris Slutsky
Pull out and check each fuse one at a time. Try not to mix them up,
though.
Phil Allison
"adam69"
> My Peavey VTM-120 stopped working. It turns on, but the tube don't glow.
> Could it be that one of the fuses have blown? It has three of them, but
> I'm not sure what they're all for. Any guesses?
** The 8A fuse on the PSU board is the one.
Must be replaced with a SLOW acting fuse.
.... Phil
boardjunkie
Heater circuit has overheated connectors. I'd have someone hardwire it
for you (eliminates the connectors altogether)so this won't happen
again.
adam79
I took out the chassis, and it looks like all the fuses are stable. When
a fuse is blown, the wire is broken, right? There is one fuse labeled
"FBA" that is opaque, hence I can't see the wire. I took it out and
shook it, but it was solid.. I'm not sure if it would jingle if blown?
What is the FBA fuse for? There's also a 5 amp fuse right next to the
power cord, but I assume if that one was blown the amp wouldn't turn on.
I don't have any meters to measure anything. I ordered a cheap
multi-meter three weeks ago, but it's still in transit;
HarborFreight.com takes forever with shipping. I'm utterly broke, and
out of work, so I have no idea when I'll be able to bring it to a tech.
This sucks!
-Adam
boardjunkie
You don't know someone with a meter you could borrow for 5 mins? The
fuse, if blown, blows for a reason....and that is connectors in the
heater circuit that go high resistance. This heats them up and wrecks
them. The header pins can also break loose at the solder joint
compounding the problem. This amp...and I have 2 of them....is
*notorious* for flaming up the heater connectors. They weren't rated
for the job to begin with and *will* fail...count on it. If you have
it hardwired the problem will be gone.
adam79
>
> You don't know someone with a meter you could borrow for 5 mins? The
> fuse, if blown, blows for a reason....and that is connectors in the
> heater circuit that go high resistance. This heats them up and wrecks
> them. The header pins can also break loose at the solder joint
> compounding the problem. This amp...and I have 2 of them....is
> *notorious* for flaming up the heater connectors. They weren't rated
> for the job to begin with and *will* fail...count on it. If you have
> it hardwired the problem will be gone.
It sounds like something I'd get done, if i had more than 5 dollars in
my pocket. Like I was saying, I ordered a multi-meter, but it's still in
transit. Unfortunately I don't know anyone, enough on a personal level
anyways, that has the tools, and the know-how.. I bought the amp years
ago from this guy who hadn't used it for a couple years. It still has
all the original tubes, and I'd guess every component is the stock ones
the amp came with.. I'd love to get it tuned up and re-tubed, but again,
money issues. Is it true that this amp is fixed biased? I forget who
told me, I think some guy on a Peavey forum. When I get some cash in
hand, what type of tubes does the amp like? Are tubes only as good as
their manufacturer for most amps, or do amps take better to different
brands (of tubes) over others? Oh yeah, one more thing, is it bad to
power an amp on/off with the standby off?
I was reading somewhere that there's a mod to turn the amp into 2
channels. Are you familiar with this one? It sucks to play a show and
have to use a distortion pedal (I need to switch between clean n' dirty)
when the amp's gain is so badass. I started using my Lexicon MPX1 in the
effects loop w/ the Guitar Cab EQ preset (on A [closed back]); it turns
the thing into a monster. Although the compression or gate on the preset
takes away the sustain. I have to read the manual and learn how to tweak
the presets properly. Out of curiosity, what dip-switches do you use
when you want a heavy sound? I like Gain 2 and Low 2.
Thanks for the help,
-Adam
Phil Allison
"boardjunkie" = jerkoff
You don't know someone with a meter you could borrow for 5 mins? The
fuse, if blown, blows for a reason....
** That 8 amp heater fuse blows for NO good reason all the time.
Failures always occur at switch on, due to the very high current flow while
the filaments are cold.
and that is connectors in the heater circuit that go high resistance.
** Cleary would REDUCE the chances of the same fuse blowing.
Wot a fucking imbecile !!!!!!!
.... Phil
Jim
> boardjunkie wrote:
>>
>> You don't know someone with a meter you could borrow for 5 mins? The
>> fuse, if blown, blows for a reason....and that is connectors in the
>> heater circuit that go high resistance. This heats them up and wrecks
>> them. The header pins can also break loose at the solder joint
>> compounding the problem. This amp...and I have 2 of them....is
>> *notorious* for flaming up the heater connectors. They weren't rated
>> for the job to begin with and *will* fail...count on it. If you have
>> it hardwired the problem will be gone.
>
> It sounds like something I'd get done, if i had more than 5 dollars in
> my pocket. Like I was saying, I ordered a multi-meter, but it's still in
> transit.
I'll butt into the conversation...
I assume it was on a credit card? If it hasn't shipped yet, CANCEL the
order and buy a cheapie locally. I doubt it'd be any more money without
the shipping.
-or-
Got a small flashlight? You could check the fuses with that. ...at
least any fuse other than tiny values. You just complete the circuit
from battery to bulb with fuse in the path. Doesn't light? Bad fuse.
I didn't see you explain HOW the fuse popped (if when turned on, if when
cranked, made a noise before popping...). But it's likely that there is
some sort of fault, it'll just pop again.
> Unfortunately I don't know anyone, enough on a personal level
> anyways, that has the tools, and the know-how.. I bought the amp years
> ago from this guy who hadn't used it for a couple years. It still has
> all the original tubes, and I'd guess every component is the stock ones
> the amp came with.. I'd love to get it tuned up and re-tubed, but again,
> money issues. Is it true that this amp is fixed biased?
You do understand that fixed bias doesn't mean that you can slap any
tubes in, right? Fixed means that it's not cathode biased. It may lack
a bias pot for adjustment, but bias should still be checked (once new
matched tubes are installed). A tech would measure static dissipation
and change a bias resistor or two (if needed).
> I forget who
> told me, I think some guy on a Peavey forum. When I get some cash in
> hand, what type of tubes does the amp like? Are tubes only as good as
> their manufacturer for most amps, or do amps take better to different
> brands (of tubes) over others?
I think some tubes sound better in some amps, either due to plate
voltages or load from the OT (output transformer), or both.
I use vintage tubes, because I have a small hoard. If I had to buy
6L6GC, I'd prefer SED "Winged C."
http://www.tubedepot.com/sv-6l6gc.html
You need a matched QUAD. Verify that your tech will use tubes from
other sources, or see if he'll get close on price. Don't be too
surprised if he tries to say Sovtek (or whatever he has in stock) are
more than adequate.
> Oh yeah, one more thing, is it bad to
> power an amp on/off with the standby off?
The amp should be in standby position when power up. It's less
important when powering down, but most guys go into standby, then power
down. That way it's already in standby when you power back up.
boardjunkie
> "boardjunkie" = jerkoff
>
> You don't know someone with a meter you could borrow for 5 mins? The
> fuse, if blown, blows for a reason....
>
> ** That 8 amp heater fuse blows for NO good reason all the time.
>
> Failures always occur at switch on, due to the very high current flow while
> the filaments are cold.
Yea? Mine has the original heater fuse in it and I used this amp for
10-12 yrs straight. But....I hardwired the filaments.
>
> and that is connectors in the heater circuit that go high resistance.
>
> ** Cleary would REDUCE the chances of the same fuse blowing.
Do yer homework and get back with me....
Actually, no. I'll do it for you.
A quick google gets you this from wikipedia....
"A sufficiently high contact resistance can cause substantial heating
in a high current device."
>
> Wot a fucking imbecile !!!!!!!
>
> .... Phil
Wot....R U a freakin 12 y o R sumthin? Now go fuck yerself....
Phil Allison
>
> ** That 8 amp heater fuse blows for NO good reason all the time.
>
> Failures always occur at switch on, due to the very high current flow
> while
> the filaments are cold.
Yea?
** Yeah - replaced one only a week ago in a PV Triumph 120.
Mine has the original heater fuse in it
** Yawnnnnnnnnnnnnnnnnnnnnnnnnn.....
> and that is connectors in the heater circuit that go high resistance.
>
> ** Cleary would REDUCE the chances of the same fuse blowing.
Do yer homework and get back with me....
** Piss off to HELL - fuckwit !!
A quick google gets you this from wikipedia....
"A sufficiently high contact resistance can cause substantial heating
in a high current device."
** ROTFL
UTTERLY, UTTERLY IRRELEVANT
You FUCKING IMBECILE !!!
.... Phil
boardjunkie
> ** Yeah - replaced one only a week ago in a PV Triumph 120.
Who gives a shit....
> A quick google gets you this from wikipedia....
>
> "A sufficiently high contact resistance can cause substantial heating
> in a high current device."
>
> ** ROTFL
>
> UTTERLY, UTTERLY IRRELEVANT
>
> You FUCKING IMBECILE !!!
>
> .... Phil
Waaaah!boo hoo! No everyone! LOOK AT MEEEE!!!!!!!! OVER HERE!!!!!!
MEEEEEEEE!!!!
Piss up a rope pole puffer.....
http://norwegianity.files.wordpress.com/2009/11/files_troll_2.jpg
Phil Allison
" boardjunkie" = fucking jerkoff
> ** That 8 amp heater fuse blows for NO good reason all the time.
>
> Failures always occur at switch on, due to the very high current flow
> while the filaments are cold.
** Piss off to HELL -
You FUCKING IMBECILE !!!
.... Phil
adam79
>
> I'll butt into the conversation...
>
> I assume it was on a credit card? If it hasn't shipped yet, CANCEL the
> order and buy a cheapie locally. I doubt it'd be any more money without
> the shipping.
Correct, but I have the tracking number and it's on the way.
>
> Got a small flashlight? You could check the fuses with that. ...at
> least any fuse other than tiny values. You just complete the circuit
> from battery to bulb with fuse in the path. Doesn't light? Bad fuse.
>
I'll try it. Is the 8 amp heater fuse the "FBA" ceramic one? When I go
to by this fuse at Radio Shack, will it be labeled as an 8 amp heater
fuse, a FBA fuse, or something else? I want to make sure I'm buying the
correct one.
> I didn't see you explain HOW the fuse popped (if when turned on, if when
> cranked, made a noise before popping...). But it's likely that there is
> some sort of fault, it'll just pop again.
>
No noise at all. It was working perfectly. I turned the power on and off
with the standby off, and it was soon after I noticed the tubes weren't
lighting.
In response to boardjunkie about the heater connectors being handwired,
is there any literature you can point me to that explains how this is
done. Is it a common mod with the VTM-120s, or is it something that you
decided to do on your own?
Thanks,
-Adam
boardjunkie
Care to explain why the original fuse still resides in the VTM head I
bought new in 1990 then?
Waiting......
Thats what I thought.
http://norwegianity.files.wordpress.com/2009/11/files_troll_2.jpg
You really should get out of mommy's basement more often....yer losin'
it......
Phil Allison
"adam69"
>
> I'll try it. Is the 8 amp heater fuse the "FBA" ceramic one? When I go to
> by this fuse at Radio Shack, will it be labeled as an 8 amp heater fuse, a
> FBA fuse, or something else? I want to make sure I'm buying the correct
> one.
** Ask for an 8 amp " slo-blo " type fuse in 3AG size - take the old fuse
with you is best.
It don't matter a hoot is if is ceramic or glass.
..... Phil
Phil Allison
adam79
Thank you for the peaceful response. You big teddy bear.
boardjunkie
> On Thu, 25 Feb 2010 01:22:37 -0500, adam79 <ada...@toast.net>wrote:
>
> >In response to boardjunkie about the heater connectors being handwired,
> >is there any literature you can point me to that explains how this is
> >done. Is it a common mod with the VTM-120s, or is it something that you
> >decided to do on your ow
>
> different boards. The power supply board filament is connected to the
> main board with a cable onto pins soldered into the board. I've seen
> some bad solder jobs on these connectors. Hard wiring would consist
> of bypassing these connectors with two wires around 14 gauge soldered
> between the two connectors. If you don't have the skills or tools the
> point is moot.
14awg? I don't think so. All you need to do is use the existing grey
ribbon cable, just solder it to the board on both ends after removing
the header pins from the boards and the socket connectors from the
cable. Easy.....
http://farm3.static.flickr.com/2548/4387206343_bdaa70f854.jpg
Have a look at that pix. The 8 pos connector gets heater voltage from
one board to the other. I don't remember which of the other connectors
supplies the 6.3v from the power supply pcb...you'll have to trace
that out. I'd replace that one as well just to bomb proof the heater
supply.
adam79
>
> ** Ask for an 8 amp " slo-blo " type fuse in 3AG size - take the old fuse
> with you is best.
>
> It don't matter a hoot is if is ceramic or glass.
>
>
>
> ..... Phil
>
>
>
I bought the 8amp slo-blo glass fuse. The amp works again, and it sounds
phenomenal! The one thing that I've noticed is that the tubes barely
light up. There is only a small orange glimmer at the base and top of
the tube. Is this because the slo-blo fuse takes longer to heat up? Is
it bad for the tubes, and/or amp, to play them when they (the tubes) are
the way I described?
Thanks,
-Adam
RD Jones
> I bought the 8amp slo-blo glass fuse. The amp works again, and it sounds
> phenomenal! The one thing that I've noticed is that the tubes barely
> light up. There is only a small orange glimmer at the base and top of
> the tube. Is this because the slo-blo fuse takes longer to heat up?
No, the presence or absence of a fuse inline with the filaments
should not effect the voltage by any _significant_ amount.
That is, of course, until the load exceeds the current rating of
the fuse at which point the fuse will heat up increasing it's
resistance and eventually blowing open.
Some tubes natually appear to glow more than others due to
how the filaments are constructed and how much protrudes
beyond the cathode.
> Is
> it bad for the tubes, and/or amp, to play them when they (the tubes) are
> the way I described?
If the voltage is at or very near 6.3 VAC at the tube socket
farthest away from the supply you are good.
When, or if, you get your meter you can measure that voltage
but as has been repeatedly said,
!!! PLEASE USE EXTREME CAUTION !!!
when poking around in a live tube amp, as well as shortly after
powering off.
rd
adam79
>
> I think some tubes sound better in some amps, either due to plate
> voltages or load from the OT (output transformer), or both.
>
> I use vintage tubes, because I have a small hoard. If I had to buy
> 6L6GC, I'd prefer SED "Winged C."
>
I have Winged C EL34s in the last Marshall JMP I had. That Marshall also
had Mullard Blackburn 76s in the pre-amp. That guy I was telling you
about that's Joe Perry's Marshall tech swears by Electro-Harmonix tubes.
For vintage tubes, do Mullards reign supreme no matter what type of
tube? If not, what would be considered the best vintage 6L6GCs? It'd be
nice to get my hands on some vintage Mullards, but they're super
expensive, and hard to find; I don't trust tube sellers on Ebay. If I
was to located a local seller, how do I test the tubes for quality,
microphonics, etc. Also, is there a way to measure how much life is left
in a tube?
Thanks,
-Adam
Jim
The basic question was answered.
But I gotta add this: Check the glow level of the tubes when the amp
has been on for a minute, then check back a half hour or so later. If
you are seeing glow on the plates, it's a sign of trouble (too low bias
voltage, too much current, plates actually glowing).
Phil Allison
"Jim"
> But I gotta add this: Check the glow level of the tubes when the amp has
> been on for a minute, then check back a half hour or so later. If you are
> seeing glow on the plates, it's a sign of trouble (too low bias voltage,
> too much current, plates actually glowing).
** To do this check, the room must be dark or almost dark or dull glowing
plates will not be visible.
.... Phil
Jim
> Jim wrote:
>>
>> I think some tubes sound better in some amps, either due to plate
>> voltages or load from the OT (output transformer), or both.
>>
>> I use vintage tubes, because I have a small hoard. If I had to buy
>> 6L6GC, I'd prefer SED "Winged C."
>>
>
> I have Winged C EL34s in the last Marshall JMP I had. That Marshall also
> had Mullard Blackburn 76s in the pre-amp. That guy I was telling you
> about that's Joe Perry's Marshall tech swears by Electro-Harmonix tubes.
I don't care for EH preamp tubes, but I can't comment on 6L6GC.
>
> For vintage tubes, do Mullards reign supreme no matter what type of
> tube?
Mullard was known for high quality tubes across the board. I can't
speak for anything other than the 12AX7 and EL84, because that's where
my playing experience is. They just sound the best to me, and they do
last.
> If not, what would be considered the best vintage 6L6GCs?
"Common wisdom" says black plate RCA. I have several, and they do sound
great. But I also like GE and Sylvania.
> It'd be
> nice to get my hands on some vintage Mullards, but they're super
> expensive, and hard to find; I don't trust tube sellers on Ebay.
It's a crap shoot, but I've managed to come out on top. That was a few
years back. Probably more culls and crap being sold at this point.
When I did buy US 6L6GC used from ebay, my net cost was far less per
tube than Winged C. But I also know how to check bias, and match tubes
up.
> If I
> was to located a local seller, how do I test the tubes for quality,
> microphonics, etc. Also, is there a way to measure how much life is left
> in a tube?
It's not rocket science, but more than you want to deal with. I use a
Hickok 6000A tube tester. Then I check bias in the amp that the tubes
will reside in. I call them matched if all tubes are withing 10% for
BOTH variables. Then I use my EARS.
>
> Thanks,
> -Adam
adam79
>
>> If not, what would be considered the best vintage 6L6GCs?
>
> "Common wisdom" says black plate RCA. I have several, and they do sound
> great. But I also like GE and Sylvania.
>
I was reading some reviews on current stock 6L6GC tubes, and the
JAN-Phillips 6L6GC was always the reviewers top pick. For the EH tubes,
I was reading that you don't always know what you're getting since they
aren't made by anyone specific.
Thanks bud,
-Adam
adam79
the fuse blew. Also, luckily all the ribbon connectors show no signs of
discoloration, fatigue or damage.. referring back to the hardwire bypass.
-Adam
Phil Allison
"adam69"
>I commented on the tube glow because they glowed much brighter before the
>fuse blew.
** Utter self delusion.
Yawnnnnnnnnnnnnnnnnnnnnnnnnnnn....
.... Phil
adam79
Are you saying that I can't tell the difference between how the tubes
glowed for the past 7 years, and how they dimmed with the replacement of
the fuse?
It's not 69, it's adam79; take your hands off your cock for a moment.
Jim
Adam,
I gotta tell ya, I'm also skeptical.
For the glow to be not as bright now, and brighter before, ONLY at the
filaments, I can't think of any other reasons but:
The voltage dropped. I suppose it's possible that some of the windings
on the filament supply shorted when whatever caused the fuse to pop
happened. When you get your meter, you could measure this. You could
even cheat by pulling a tube and measuring the right points in the
socket (rather than working around an open chassis).
-or-
You were seeing the plates glowing (which is why I said check after one
minute, and again after you're done playing).
-or-
You're mistaken.
adam79
> Adam,
>
> I gotta tell ya, I'm also skeptical.
>
> For the glow to be not as bright now, and brighter before, ONLY at the
> filaments, I can't think of any other reasons but:
>
> The voltage dropped. I suppose it's possible that some of the windings
> on the filament supply shorted when whatever caused the fuse to pop
> happened. When you get your meter, you could measure this. You could
> even cheat by pulling a tube and measuring the right points in the
> socket (rather than working around an open chassis).
>
> -or-
>
> You were seeing the plates glowing (which is why I said check after one
> minute, and again after you're done playing).
>
> -or-
>
> You're mistaken.
>
>
The 8 amp slo blo fuse is rated at 250 volts. Before I replaced it, I
checked with a tech at a local repair shop, and he said that the voltage
rating of the fuse was alright. Was I given the right information?
I'll check the tubes to see if the plate voltage glows, and report back.
While the amp is warming up, should I keep the standby on for the first
30 minutes, check the tubes, then play the amp, and check it again?
On another topic, someone on this newsgroup told me that the VTM-120 is
a hybrid amp, but on the Peavey forum, I was told it's all tube. I did
some more research, and read it was a Class A/B tube amp. Which one is
it? All tube or hybrid?
Thanks,
-Adam
Phil Allison
"adam69"
>>
>>
>>> I commented on the tube glow because they glowed much brighter before
>>> the fuse blew.
>>
>>
>> ** Utter self delusion.
>>
>> Yawnnnnnnnnnnnnnnnnnnnnnnnnnnn....
>>
>>
>
> Are you saying that I can't tell the difference between how the tubes
> glowed for the past 7 years, and how they dimmed with the replacement of
> the fuse?
** Yep.
You are a completely stupid idiot.
Fuck off.
.... Phil
boardjunkie
> I'll check the tubes to see if the plate voltage glows, and report back.
> While the amp is warming up, should I keep the standby on for the first
> 30 minutes, check the tubes, then play the amp, and check it again?
>
Turn the amp on in standby. Leave it sit for a minute or 2, then
switch to run. Leave it in run until you're ready to turn it off.
Switching the standby on/off shortens the life of the output tubes due
to thermal stress.
> On another topic, someone on this newsgroup told me that the VTM-120 is
> a hybrid amp, but on the Peavey forum, I was told it's all tube. I did
> some more research, and read it was a Class A/B tube amp. Which one is
> it? All tube or hybrid?
>
Its all tube. Hybrid amp normally means solid state preamp/tube pwr
amp or the other way around.
> Thanks,
> -Adam
adam79
Wow.
This is way off topic, but are you a religious man (god and country,
pro-life, anti stem-cell)? Republican?
TD Madden
Les Cargill
Phil seems to score low in "agreeableness". Font of great info, tho.
--
Les Cargill
Jim
> Jim wrote:
>> Adam,
>>
>> I gotta tell ya, I'm also skeptical.
>>
>> For the glow to be not as bright now, and brighter before, ONLY at the
>> filaments, I can't think of any other reasons but:
>>
>> The voltage dropped. I suppose it's possible that some of the windings
>> on the filament supply shorted when whatever caused the fuse to pop
>> happened. When you get your meter, you could measure this. You could
>> even cheat by pulling a tube and measuring the right points in the
>> socket (rather than working around an open chassis).
>>
>> -or-
>>
>> You were seeing the plates glowing (which is why I said check after
>> one minute, and again after you're done playing).
>>
>> -or-
>>
>> You're mistaken.
>>
>>
>
> The 8 amp slo blo fuse is rated at 250 volts. Before I replaced it, I
> checked with a tech at a local repair shop, and he said that the voltage
> rating of the fuse was alright. Was I given the right information?
Yes, the critical value is 8A, not 250V.
>
> I'll check the tubes to see if the plate voltage glows, and report back.
> While the amp is warming up, should I keep the standby on for the first
> 30 minutes, check the tubes, then play the amp, and check it again?
Let me back up a couple of steps, and make this a bit simpler.
There's a chance you were seeing a "runaway" situation, where plates
start to glow from excessive heat.
Here's a good way to check:
You need a dark room, so it's best to do it at night. Turn on the amp
but leave it in standby. Take a GOOD LOOK at your tubes, and remember
what you're seeing.
Now, take it off of standby. You don't even need to plug in a guitar.
Just leave the amp on. Watch TV. Waste some time on AGA. Just DO NOT
sit there and constantly watch the tubes (because you can miss gradual
changes that way).
After 15 minutes, shut off the lights, look at the tubes. Look the
same? GOOD. Leave it another 15 minutes. Check again. Look the same?
Everything is fine.
The tubes should look THE SAME.
If the plates start to glow, you have a bias problem. Too low of a bias
voltage allows too much current through the tubes. The excessive
current causes excessive heat, and the plates begin to glow.
More detail:
There's no value in keeping an amp on standby (when powering up) for
more than a couple of minutes. The purpose of standby is to give the
filaments (AKA heaters) enough time to heat the tubes up to minimum
operating temperature. ...which happens in about 30 seconds to a minute
for common amp tubes. If you play an amp before the tube is heated up,
you can cause premature and unnecessary wear. Google "cathode
stripping." If you have an amp with no standby, just keep the volume
off for a minute before playing.
Use of standby after amp is already heated up (during a set break, for
example) is a totally different issue. I don't gig, but if I'm going to
be away from the amp for a few minutes, I leave it ON (not on standby).
If I'm going to be away long enough to worry about putting it in
standby, I'd just as soon turn it off.
>
> On another topic, someone on this newsgroup told me that the VTM-120 is
> a hybrid amp, but on the Peavey forum, I was told it's all tube. I did
> some more research, and read it was a Class A/B tube amp. Which one is
> it? All tube or hybrid?
How many tubes does it have?
Peavey has a good website with archived manuals including schematics.
http://www.peavey.com/assets/literature/manuals/80300704.pdf tells me
that your amp has four power tubes and one DRIVER tube. So it's a
hybrid. Solid state preamp, tube power amp. If there was a VTM-120
with a tube preamp, I don't see it listed.
But, again, count the tubes. Only one preamp sized tube? It's a hybrid.
I'm not gonna tell you "that's bad." I own a Peavey Mace. A hybrid.
>
> Thanks,
> -Adam
Jim
Phil doesn't bother me any more. Because I KILL-FILED him! Try it.
jh
This one or the sylvania 7581 (which is the same tube) would be the no1
tube I'd pick for your particular amp, if money was no issue. Buy from a
real reliable source; ebay is imho weeded out for popular tube types and
th duds are sold there over and over.
EH are made by somone specific -sovtek aka reflector.
Jochen
jh
Jim,
the manual also states 3 12AX7 for the preamp.
a few lines later
regards
Jochen
Jim
>>
>
> Jim,
>
> the manual also states 3 12AX7 for the preamp.
> a few lines later
>
> regards
>
> Jochen
DOH!
I obviously can't keep track of all of the VT, VTX, Classic, VTM...
Sorry about that!
Jim
> On another topic, someone on this newsgroup told me that the VTM-120 is
> a hybrid amp, but on the Peavey forum, I was told it's all tube. I did
> some more research, and read it was a Class A/B tube amp. Which one is
> it? All tube or hybrid?
Make sure you check Jochen's correction of my previous post. I quit
reading when I saw one driver and four power tubes. MY MISTAKE. The
Peavey doc clearly states that the VTM-120 also has three preamp tubes.
Sorry about that!
adam79
> This one or the sylvania 7581 (which is the same tube) would be the no1
> tube I'd pick for your particular amp, if money was no issue. Buy from a
> real reliable source; ebay is imho weeded out for popular tube types and
> th duds are sold there over and over.
>
> EH are made by somone specific -sovtek aka reflector.
>
> Jochen
Yeah. EHs are made by New Sensor. I've been talking to the guy a
tubedepot.com. A matched-quad of EH 6L6GCs are $66, compared to $100 for
the SED Winged "C;" they sell the JAN Phillips 6L6GC STR variant, but
they are $50/per tube. Do you also look down on the EHs?
-Adam
adam79
> On 2/26/2010 2:33 PM, adam79 wrote:
>
> There's a chance you were seeing a "runaway" situation, where plates
> start to glow from excessive heat.
>
> Here's a good way to check:
>
> You need a dark room, so it's best to do it at night. Turn on the amp
> but leave it in standby. Take a GOOD LOOK at your tubes, and remember
> what you're seeing.
>
> Now, take it off of standby. You don't even need to plug in a guitar.
> Just leave the amp on. Watch TV. Waste some time on AGA. Just DO NOT
> sit there and constantly watch the tubes (because you can miss gradual
> changes that way).
>
> After 15 minutes, shut off the lights, look at the tubes. Look the
> same? GOOD. Leave it another 15 minutes. Check again. Look the same?
> Everything is fine.
>
I checked the tubes. The plates do not glow. When first powered on, the
the tubes only have the orange filament glow. After 30 minutes, the rest
of the tubes lighten with a blue glow; this is what they look liked
before the fuse blew. It never took as long as it does now for them to
warm up. I'm assuming once they are glowing blue, they are warmed up,
right? Is the 8 amp slo-blo fuse causing the increased warm-up time? I
unfortunately noticed that the 3rd power tube in from the left never
failed to glow blue. I assume that I will need to replace the power
tubes.. GUH! Just out of curiosity, would replacing the OT and choke
with a higher-end brand (Mercury Magnetics) increase the sound quality
enough to justify spending $300 for the parts (OT and choke). Someone in
the Peavey newsgroup suggested I do this for better tone, so I checked
into it.. It would be something I would have to do later down the road
due to my lack of money, but I'm just wondering if you think it's worth
the money..?
In response to the pre-amp post, the amp has 4 pre-tubes. In the manual
it states that there is one that drives the power tubes, and then three
more in the pre-amp section. Does this mean that the amp is an all tube
Class A/B and not a hybrid?
Thanks for the help,
-Adam
boardjunkie
> I checked the tubes. The plates do not glow. When first powered on, the
> the tubes only have the orange filament glow. After 30 minutes, the rest
> of the tubes lighten with a blue glow; this is what they look liked
> before the fuse blew. It never took as long as it does now for them to
> warm up. I'm assuming once they are glowing blue, they are warmed up,
> right? Is the 8 amp slo-blo fuse causing the increased warm-up time? I
> unfortunately noticed that the 3rd power tube in from the left never
> failed to glow blue. I assume that I will need to replace the power
> tubes.. GUH!
No you don't.....that blue glow doesn't *have* to be there.
http://www.jacmusic.com/html/articles/blueglow/blueglow.htm
Just out of curiosity, would replacing the OT and choke
> with a higher-end brand (Mercury Magnetics) increase the sound quality
> enough to justify spending $300 for the parts (OT and choke). Someone in
> the Peavey newsgroup suggested I do this for better tone, so I checked
> into it.. It would be something I would have to do later down the road
> due to my lack of money, but I'm just wondering if you think it's worth
> the money..?
Yer amp doesn't have a choke. I wouldn't bother replacing the output
xfmr either.
>
> In response to the pre-amp post, the amp has 4 pre-tubes. In the manual
> it states that there is one that drives the power tubes, and then three
> more in the pre-amp section. Does this mean that the amp is an all tube
> Class A/B and not a hybrid?
Dude.....its all tube....end of story.
boardjunkie
> On Feb 27, 3:25 am, adam79 <ada...@toast.net> wrote:
>
> > I checked the tubes. The plates do not glow. When first powered on, the
> > the tubes only have the orange filament glow. After 30 minutes, the rest
> > of the tubes lighten with a blue glow; this is what they look liked
> > before the fuse blew. It never took as long as it does now for them to
> > warm up. I'm assuming once they are glowing blue, they are warmed up,
> > right? Is the 8 amp slo-blo fuse causing the increased warm-up time? I
> > unfortunately noticed that the 3rd power tube in from the left never
> > failed to glow blue. I assume that I will need to replace the power
> > tubes.. GUH!
>
>
> Just out of curiosity, would replacing the OT and choke
>
> > with a higher-end brand (Mercury Magnetics) increase the sound quality
> > enough to justify spending $300 for the parts (OT and choke). Someone in
> > the Peavey newsgroup suggested I do this for better tone, so I checked
> > into it.. It would be something I would have to do later down the road
> > due to my lack of money, but I'm just wondering if you think it's worth
> > the money..?
>
> Yer amp doesn't have a choke. I wouldn't bother replacing the output
> xfmr either.
>
>
>
> > In response to the pre-amp post, the amp has 4 pre-tubes. In the manual
> > it states that there is one that drives the power tubes, and then three
> > more in the pre-amp section. Does this mean that the amp is an all tube
> > Class A/B and not a hybrid?
>
> Dude.....its all tube....end of story.
>
>
>
>
>
> > Thanks for the help,
>
> - Show quoted text -
And....before you start thinking of all this other shit, you better
get your heater circuit hardwired. Or risk damage and a larger repair
bill down the road.
adam79
> On Feb 27, 8:56 am, boardjunkie <boardjun...@techie.com> wrote:
>> No you don't.....that blue glow doesn't *have* to be there.http://www.jacmusic.com/html/articles/blueglow/blueglow.htm
>>
Thanks for the link. I was actually reading about the tube glow, and
stumbled on that exact link. The blue glow is just between the plates,
on the three that glow blue.
>
> And....before you start thinking of all this other shit, you better
> get your heater circuit hardwired. Or risk damage and a larger repair
> bill down the road.
I realize that, and was also told the same thing by the tech I talked
to. It's hard not to play the amp since it sounds so great. I'll have to
gather up some will power and just use my Music Man until I can get the
VTM in the shop.
Thanks,
-Adam
adam79
are the sound differences? The SL-X is a hybrid, right? Also, if you or
anyone else knows the SL-X, is there a difference in sound between the
50 and 100 watt models, or are the 100 watt ones just louder?
Thanks,
-Adam
Jim
> Jim wrote:
>> On 2/26/2010 2:33 PM, adam79 wrote:
>
>>
>> There's a chance you were seeing a "runaway" situation, where plates
>> start to glow from excessive heat.
>>
>> Here's a good way to check:
>>
>> You need a dark room, so it's best to do it at night. Turn on the amp
>> but leave it in standby. Take a GOOD LOOK at your tubes, and remember
>> what you're seeing.
>>
>> Now, take it off of standby. You don't even need to plug in a guitar.
>> Just leave the amp on. Watch TV. Waste some time on AGA. Just DO NOT
>> sit there and constantly watch the tubes (because you can miss gradual
>> changes that way).
>>
>> After 15 minutes, shut off the lights, look at the tubes. Look the
>> same? GOOD. Leave it another 15 minutes. Check again. Look the same?
>> Everything is fine.
>>
>
> I checked the tubes. The plates do not glow. When first powered on, the
> the tubes only have the orange filament glow. After 30 minutes, the rest
> of the tubes lighten with a blue glow; this is what they look liked
> before the fuse blew. It never took as long as it does now for them to
> warm up. I'm assuming once they are glowing blue, they are warmed up,
> right?
No. The blue glow is electrons interacting with residual gasses in the
tube. Some amount is acceptable. It can increase if a tube loses
vacuum. A "gassy" tube. ...then the filament will burn out.
Unless there's a lot of it, it's nothing to worry about. Try cranking
the amp and hitting a couple of power chords, while watching the glow.
> Is the 8 amp slo-blo fuse causing the increased warm-up time?
No. There is very little voltage drop over fuses.
> I
> unfortunately noticed that the 3rd power tube in from the left never
> failed to glow blue. I assume that I will need to replace the power
> tubes.. GUH! Just out of curiosity, would replacing the OT and choke
> with a higher-end brand (Mercury Magnetics) increase the sound quality
> enough to justify spending $300 for the parts (OT and choke).
I wouldn't. I'd use the money towards a second amp.
> Someone in
> the Peavey newsgroup suggested I do this for better tone, so I checked
> into it.. It would be something I would have to do later down the road
> due to my lack of money, but I'm just wondering if you think it's worth
> the money..?
If you think this amp is THE amp for you, maybe you can justify the
expense. Mercury Magnetics makes good transformers. If they have one
that they claim to have tweaked for that exact model amp, I'm sure it
sounds good. But I'd still use the money towards something different.
>
> In response to the pre-amp post, the amp has 4 pre-tubes. In the manual
> it states that there is one that drives the power tubes, and then three
> more in the pre-amp section. Does this mean that the amp is an all tube
It means you have a tube preamp. There are amps with a tube preamp that
are not "all tube." Some amps have solid state reverb drivers and/or
solid state effects loop section, or even tremolo with solid state
components.
> Class A/B and not a hybrid?
You have a tube preamp. I haven't looked at a schematic, so I won't
make two mistakes in two days by assuring you that it is "all tube."
But I bet it is.
Jim
So the upgrade to Winged C only sets you back $8.50 a tube. If you
don't do it, I predict you'll always wonder if you should've.
adam79
I was talking to that guy who is Joe Perry's guitar tech, asking him
about 6L6 tubes. He said that the best ones are Groove Tube 6L6GE Clear
Tops. He went on to say that Groove Tube bought the machine from General
Electric that makes the tubes. Does anyone have these tubes? Any
comments on them?
Thanks,
-Adam
boardjunkie
The SL-X is the 6100 ainnit? I dunno. Never had one in my shop. A
buddy of mine has the 6100, but I've not heard it in years. But, I
*will* say that the sound of a *good* VTM blows away most modern
marshalls. The VTMs seem to vary a bit. The later ones sounded a bit
better IME. I have one that I bought new in 90 and a 1987 model. The
newer one just has *that* sound. The older one is good, but not *as*
good.
boardjunkie
>
> - Show quoted text -
I've seen failures of the GT reissue 6L. It ain't no better than
anything else out there. JJ or SED is the way to go. I kinda like the
Ruby 6L6GCMSTR as well....gigged a quad of those out for 2 years now
with no problems. The EH 6Ls ain't bad either for a budget
tube.....just don't stick 'em in an amp with screen taps....
adam79
The SL-X is the 2500 (50 watts) and 2100 (100 watts). The schematics
never changed for the entirety of the VTMs production run.
adam79
Really? I found a great price on a matched quad of the GT 6L6GEs; $109 @
Sweetwater.com (on sale from $159). GT makes other 6L6 variants; the
tech I talked to only recommended the GE. Have the failures been with
all the GT 6L6 variants?
jh
Adam,
the SL-X is not a hybrid, in contrary to the rest of the JCM900 series
regards
Jochen
boardjunkie
>
> - Show quoted text -
Ok then.....I don't paya whole lot of attention to the newer Mar$hall
stuff.....just repair it and send it out the door.
The schematic may have stayed the same, but component selection prolly
varied. With the same tubes in both heads, biased up the same....the
older one has a slightly raspy quality to the overdrive thats kind of
annoying. The newer one is a touch hotter and noticeably smoother.
But....I don't really use the VTM heads anymore. Play'n out I need a
footswitchable effect loop...which those don't have. And...they're
soooo fuckin' heavy.....
adam79
I've been trying to date mine, but I've had no luck. I think it may be
one of the earlier ones; the serial # starts with 8A. I was reading that
#s starting with 5, 6, or 7 are from the mid '80s, but haven't seen any
info on the 8A serial #. Any ideas on the components they might have
changed in the later models? When I bring it into the shop, I'd like to
replace some components with higher end ones.
Thanks,
-Adam
adam79
>
> I've seen failures of the GT reissue 6L. It ain't no better than
> anything else out there. JJ or SED is the way to go. I kinda like the
> Ruby 6L6GCMSTR as well....gigged a quad of those out for 2 years now
> with no problems. The EH 6Ls ain't bad either for a budget
> tube.....just don't stick 'em in an amp with screen taps....
Yeah, other people have told me the same thing about the GTs being
flaky. Everyone recommends the SED Winged "C." What about the JJ 6L6s?
Those are supposedly a heavier sounding tube. Since that's what type of
stuff I play, they sound interesting, but I should probably just go with
the Winged "C" since everyone likes them.
Thanks again for the help,
-Adam
jh
sure everybody likes them completely unreserved?
Sure - they do sound good, but lots of them are fairly early in their
life because of their habit to become microphonic - earlier than other
6L6es...
So the quest goes on..
My 2cts:
Have your amp checked. tere is a reasonwhy one of the tubes does *not*
exhibit blue glow. Assumed they are of the sam "make".
Do you have pics of your particular tubes? If they are of the same make,
they should behave equally. If they have the blue fluorescence in the
glass, chances are high that they are still be US-made Sylvanias. *)
Those tubes had a marvellous blue glow. Maybe the screen grid resistor
is open and the tubes have a lot of miles before them.
If they don't blow HT-fuses and if they ain't microphonic, why change them?
*) those Sylanias were The Peavey OEM-tubes when the VTMs were made.
regards
Jochen
adam79
>
> My 2cts:
> Have your amp checked. tere is a reasonwhy one of the tubes does *not*
> exhibit blue glow. Assumed they are of the sam "make".
>
> Do you have pics of your particular tubes? If they are of the same make,
> they should behave equally. If they have the blue fluorescence in the
> glass, chances are high that they are still be US-made Sylvanias. *)
> Those tubes had a marvellous blue glow. Maybe the screen grid resistor
> is open and the tubes have a lot of miles before them.
>
> If they don't blow HT-fuses and if they ain't microphonic, why change them?
>
> *) those Sylanias were The Peavey OEM-tubes when the VTMs were made.
>
> regards
>
> Jochen
Well the HT-fuse was blown, that was my original problem. I had to
replace the 8 amp "FBA" fuse. I'm gonna drop my amp off and get it
checked from top to bottom. All the tubes are the original stock tubes;
they are labeled "Peavey."
-Adam
TD Madden
boardjunkie
>
> - Show quoted text -
The VTM didn't exist until 1987. The Butcher was a similar amp in
appearance, but didn't have the option switches. That dated to around
1985. The VTM is basically a revamped Butcher.
BTW, I see that PV has a new amp now that has the Butcher name.
No....its not a reissue. Ugh....are they *completely* out of names to
call thier amps?
adam79
>>> The schematic may have stayed the same, but component selection prolly
>>> varied. With the same tubes in both heads, biased up the same....the
>>> older one has a slightly raspy quality to the overdrive thats kind of
>>> annoying. The newer one is a touch hotter and noticeably smoother.
>>> But....I don't really use the VTM heads anymore. Play'n out I need a
>>> footswitchable effect loop...which those don't have. And...they're
>>> soooo fuckin' heavy.....
>> I've been trying to date mine, but I've had no luck. I think it may be
>> one of the earlier ones; the serial # starts with 8A. I was reading that
>> #s starting with 5, 6, or 7 are from the mid '80s, but haven't seen any
>> info on the 8A serial #. Any ideas on the components they might have
>> changed in the later models? When I bring it into the shop, I'd like to
>> replace some components with higher end ones.
>>
>> Thanks,
>> -Adam
>>
>
> The VTM didn't exist until 1987. The Butcher was a similar amp in
> appearance, but didn't have the option switches. That dated to around
> 1985. The VTM is basically a revamped Butcher.
>
> BTW, I see that PV has a new amp now that has the Butcher name.
> No....its not a reissue. Ugh....are they *completely* out of names to
> call thier amps?
Interesting. So do any idea about what year my VTM is from; the serial #
starts with "8A," does that show up on either of your VTMs?
Also, I'm gonna be bringing my amp into the shop tomorrow (Monday), so
if you know which components were upgraded in the later models, it would
be a great time to let me know.
Thanks for all the help,
-Adam
jh
Your fuse was the "HEATER"-Fuse - not the HT Fuse.
HT: High Tension - not HEATER
Jochen
Greasehorse
>Morris Slutsky wrote:
>> On Feb 23, 9:22 pm, adam79 <ada...@toast.net> wrote:
>>> My Peavey VTM-120 stopped working. It turns on, but the tube don't glow.
>>> Could it be that one of the fuses have blown? It has three of them, but
>>> I'm not sure what they're all for. Any guesses?
>>>
>>> Thanks,
>>> -Adam
>>
>> Pull out and check each fuse one at a time. Try not to mix them up,
>> though.
>>
>
>I took out the chassis, and it looks like all the fuses are stable. When
>a fuse is blown, the wire is broken, right? There is one fuse labeled
>"FBA" that is opaque, hence I can't see the wire. I took it out and
>shook it, but it was solid.. I'm not sure if it would jingle if blown?
>What is the FBA fuse for? There's also a 5 amp fuse right next to the
>power cord, but I assume if that one was blown the amp wouldn't turn on.
>I don't have any meters to measure anything. I ordered a cheap
>multi-meter three weeks ago, but it's still in transit;
>HarborFreight.com takes forever with shipping. I'm utterly broke, and
>out of work, so I have no idea when I'll be able to bring it to a tech.
>This sucks!
>
>-Adam
Damn dude! When I suggested Harbor Freight, I figured they had one
close to you where you could just drive over and get the meter from
them directly...oh well, so much for thinking...again...lol
Greasehorse
>Jim wrote:
>> Adam,
>>
>> I gotta tell ya, I'm also skeptical.
>>
>> For the glow to be not as bright now, and brighter before, ONLY at the
>> filaments, I can't think of any other reasons but:
>>
>> The voltage dropped. I suppose it's possible that some of the windings
>> on the filament supply shorted when whatever caused the fuse to pop
>> happened. When you get your meter, you could measure this. You could
>> even cheat by pulling a tube and measuring the right points in the
>> socket (rather than working around an open chassis).
>>
>> -or-
>>
>> You were seeing the plates glowing (which is why I said check after one
>> minute, and again after you're done playing).
>>
>> -or-
>>
>> You're mistaken.
>>
>>
>
>The 8 amp slo blo fuse is rated at 250 volts. Before I replaced it, I
>checked with a tech at a local repair shop, and he said that the voltage
>rating of the fuse was alright. Was I given the right information?
>
>I'll check the tubes to see if the plate voltage glows, and report back.
>While the amp is warming up, should I keep the standby on for the first
>30 minutes, check the tubes, then play the amp, and check it again?
>
>On another topic, someone on this newsgroup told me that the VTM-120 is
>a hybrid amp, but on the Peavey forum, I was told it's all tube. I did
>some more research, and read it was a Class A/B tube amp. Which one is
>it? All tube or hybrid?
>
>Thanks,
>-Adam
An all tube hybrid amp..lol..due to - two little parts...
Greasehorse
You can send the details and SN to Peavey and they can date it for
you.
adam79
huh?
adam79
> "adam69"
>>>
>>>> I commented on the tube glow because they glowed much brighter before
>>>> the fuse blew.
>>>
>>> ** Utter self delusion.
>>>
>>> Yawnnnnnnnnnnnnnnnnnnnnnnnnnnn....
>>>
>>>
>> Are you saying that I can't tell the difference between how the tubes
>> glowed for the past 7 years, and how they dimmed with the replacement of
>> the fuse?
>
>
> ** Yep.
>
> You are a completely stupid idiot.
>
> Fuck off.
>
>
> .... Phil
>
>
Phil, do you eat Vegemite? How about those other political questions?
Did I get 'em right on the button?
adam79
>
> Adam,
>
> I gotta tell ya, I'm also skeptical.
>
> For the glow to be not as bright now, and brighter before, ONLY at the
> filaments, I can't think of any other reasons but:
>
> The voltage dropped. I suppose it's possible that some of the windings
> on the filament supply shorted when whatever caused the fuse to pop
> happened. When you get your meter, you could measure this. You could
> even cheat by pulling a tube and measuring the right points in the
> socket (rather than working around an open chassis).
>
Jim, can you explain to me how to use the mutli-meter to check the
tubes? What are the "right points?" Also, what value will I be
measuring, and what will tell me if the tube is blown or if it's still
in proper working order? Also, is there a way that I can measure the
bias resistors to see if it's matched up correctly with this meter? This
is the first meter I've owned, so I'm new to taking these kinds of
measurements.
Jim
> Jim wrote:
>>
>> Adam,
>>
>> I gotta tell ya, I'm also skeptical.
>>
>> For the glow to be not as bright now, and brighter before, ONLY at the
>> filaments, I can't think of any other reasons but:
>>
>> The voltage dropped. I suppose it's possible that some of the windings
>> on the filament supply shorted when whatever caused the fuse to pop
>> happened. When you get your meter, you could measure this. You could
>> even cheat by pulling a tube and measuring the right points in the
>> socket (rather than working around an open chassis).
>>
>
> Jim, can you explain to me how to use the mutli-meter to check the
> tubes? What are the "right points?" Also, what value will I be
> measuring, and what will tell me if the tube is blown or if it's still
> in proper working order?
With the tube OUT OF THE AMP, you can only check that the filament is
good or not. If you see a glow, there's no need to perform this test.
If you can't see a glow, go to this site:
http://www.duncanamps.com/tdsl/tubesearch.php
Type in the designator (example: 12ax7). See the picture of the tube?
Pins 4 and 5 are the ends of the filament (center tap at pin 9). You
always count from the gap or pin on the base of the tube, clockwise. So
you'd set to resistance, ohms scale, and measure between 4 and 5. You
can safely handle the probes when set to resistance because the meter
runs of a little battery at very low current, If it's open (or SEVERAL
thousand ohms if your fingers are touching) it's BAD. If it reads a
relatively low resistance, the filament has continuity (completes the
circuit, is not "open" or burnt out).
But again, the above test is a WASTE OF TIME if you can see the tube
glowing!
> Also, is there a way that I can measure the
> bias resistors to see if it's matched up correctly with this meter?
I'm sure that you appreciate that a tube amp CAN kill you. But your
worries don't end when you unplug it.
Remember: The capacitors will store a charge (sometimes for days), even
after you turn it off and unplug it! Think of them as HIGH VOLTAGE
batteries that can deliver one hell of a wallop!
There is a type of bias probe that is a relatively safe way of checking
bias, as long as you don't touch a tube pin when you're using it. You'd
need to locate the type inserts a precision 1 ohm resistor between
cathode and ground, allowing you to measure current by using the mV scale.
I don't know the seller, and I'm not endorsing the product, but check
ebay 220574041961 .
Now, I prefer the "more dangerous type," that measures actual current
through the plate. But I *can't* recommend them to others (at least not
to those who don't have a GOOD understanding of shock hazard!!!).
If you want to find the low voltage 1 ohm cathode type of bias probe
that tells you to measure using the mV scale, and you can insert/remove
power tubes without breaking them, burning yourself, or touching a pin
when the tube is slightly out of socket, you can check the current
running through your tubes. All tubes should be within 10% of each
other, from highest to lowest.
The above still doesn't tell you the quiescent dissipation, because
you'd also need to know the plate voltage. And that involves a shock
hazard! So it won't tell you if the tubes are properly biased. It WILL
tell you if one of the power tubes is way off. Realize that you could
have four tubes that are all tightly matched, but the bias voltage could
be too high or too low. Again, won't know without measuring plate
voltage on a LIVE circuit.
Tips: Get one of the "ove glove" thingies "as seen on TV" for pulling
hot tubes. Keep your hand over the end of the tube when pulling.
Better to bruise your hand than break a tube (they sometimes are a bit
stubborn, then give).
adam79
>
> But again, the above test is a WASTE OF TIME if you can see the tube
> glowing!
>
>
Since all the filaments glow, I'll bypass this test. Thanks for all the
information. As far as measuring the bias resistors, it's something I'd
like to do, but I can't afford to buy more equipment. I just saved up
enough cash to bring the amp to a tech and have it checked from top to
bottom. I also wanna get the amp hardwired to bypass those ribbon
connectors that manage the heater circuit. Hopefully all the tubes have
a good amount of life left in them.
Thanks again to everyone for all the help. I'll post an update when the
tech is done checking the amp.
-Adam
Greasehorse
Don't use a cheap meter for testing high voltages...! This started out
on speaker resistances...not killer voltage measurement...
adam79
> Don't use a cheap meter for testing high voltages...! This started out
> on speaker resistances...not killer voltage measurement...
How much does a tube tester cost? Can someone send me a link, or the
name of a good one? Also, what other meters would I need to take proper
measurements of a tube amp? Once I have some cash, I want to buy the
meters and a cheap all tube amp that I can practice on.. maybe one of
those Epiphone Valve Jr heads.
Thanks,
-Adam
Jim
> Greasehorse wrote:
>
>> Don't use a cheap meter for testing high voltages...! This started out
>> on speaker resistances...not killer voltage measurement...
>
> How much does a tube tester cost? Can someone send me a link, or the
> name of a good one?
That's a TOUGH one. I lucked out. The father to a good friend has
hundreds of thousands of tubes, and rebuilds testers. That's where I
got mine.
They can be expensive, and then may not be working right.
I use a Hickock 6000A. Check ebay 220577160429 Almost $500, with 6
days to go!
> Also, what other meters would I need to take proper
> measurements of a tube amp?
Adam, please don't take any offense to this, but... Working around live
tube amps is HAZARDOUS stuff. I have a solid foundation in electronics.
I understand the safety risks.
Unless you plan to do A LOT of learning, why bother with a quality meter?
If you want a quality meter, I use: Fluke 77/AN mil spec, previously
owned by a defense contractor.
> Once I have some cash, I want to buy the
> meters and a cheap all tube amp that I can practice on.. maybe one of
> those Epiphone Valve Jr heads.
>
> Thanks,
> -Adam
Okay. It can be a rewarding hobby, *IF* you "do your homework."
There are valuable resources on the web. START BY LEARNING. It's FREE!
Search "neets" at this page: http://www.tscm.com/reference.html
Do ALL of the relevant work. You can skip microwave, gyros, radar,
etc... But do ALL of the basic stuff, including motors.
Also, join my Guitar_Amplifiers Yahoo group, it has TONS of resources in
the links section (and some real experts as members, including Rich
Koerner and Mike Schway):
http://launch.groups.yahoo.com/group/guitar_amplifiers/ Over 650
member. ZERO politics!!!
jh
Adam,
to be honest:
a (real) tube tester is so expensive that you'd only hit the breakeven
if you had to test a lot of tubes.
A cheap tube tester of the old drugstore type (aka good/bad) won't be of
no use
It takes some knowledge to interpret the readings of a real tube tester
I don't want to bash you, but with the current state of your electronics
knowledge you'd propably be prone to electrocute yourself.
Taking readings inside a live amp is way ahead from where you are now.
Start with low voltage projects like pedals; read a lot of electronics
stuff; Unless you are *really* sure you have *understood* the working of
electronic devices *and* the basics of safety -
KEEP YOUR HANDS OUTSIDE OF A LIFE TUBE AMP.
Even an Epiphone can kill you.
With all due respect
regards
JOCHEN
Greasehorse
You need a meter rated for 1000VDC...Fluke is a good brand. Order new
or NOS (new old stock) tested tubes from LV or someone and you likely
won't need a tube tester.Something like this may work..go to Fluke and
look around for something within the 1000vdc spec...might want to get
one that will check caps also..Ebay 120544798455