Bass amp fuse question
Nil
just arrived today. I was disappointed to find that there was no fuse
in the holder in the back, so off I goes to the Radio Shack. The
voltage spec printed on the back of the amp says "110V; VAC ~50/60 Hz;
380 VA (3A @ 115V)", so I bought what I though was the closest thing:
4-Amp, 125-Volt fast acting fuses.
Now I find that the fuse blows immediately when I power the unit up. I
tried 2 fuses before I decided I'd better stop. My question is, did I
get the right fuse? They also had some 250V fuses, and some were the
slow-blow type. Do I need a 250 rather than a 125? Do I need a Slow-
Blow, rather than the quick-action one? Am I in trouble for getting a
4-amp rather than 3-amp (They didn't have any 125V 3A, but they might
have some 250V 3A.)
I need to decide if the amp is defective or not.
Gregory Rochford
Slow blow fuses are probably what you need. When the amp powers up
there's a big transient current draw.
The next part is a guess, but I think you'd want a 1.5A 250V fuse,
since the number quoted 380 VA (volt-amps). A 1.5A 250V fuse works
out to 375 VA, at least in my simplistic way of thinking about it.
Is there a Trace site/user manual to consult?
best
gr
PMG
Just about any hardware store has a better selection of fuses than
Radio Shack.
I can't tell you what fuse you're supposed to have, but it won't be a
250V one.
If that amp didn't have a fuse in it, then it sounds like you got a
piece of shit to me. I'd leave them negative feedback if they're not
willing to refund your money.
Pete
--
Ahhh... are two apes having a poop fight in here? --Hector Con Carne
Nil
wrote in news:3F5F7E01...@sbcglobal.net:
> Slow blow fuses are probably what you need. When the amp powers
> up there's a big transient current draw.
>
> The next part is a guess, but I think you'd want a 1.5A 250V fuse,
> since the number quoted 380 VA (volt-amps). A 1.5A 250V fuse
> works out to 375 VA, at least in my simplistic way of thinking
> about it.
>
> Is there a Trace site/user manual to consult?
Wow, that was quick! Thanks - now I have time to run to RS again!
Since Trace is out of business, there isn't much left. I did find some
manuals in PDF format, but they don't specify the fuse value, they just
say to get what's on the back of the amp. So, the 380VA figure is what
the fuse needs to cover?
I just noticed some more verbiage on the amp that might be pertinant:
"T3.15A @ 230V; T6.3A @ 115V; Mains Input".
Does that change anything, or is it still clear that I need a 1.5A 250V
fuse?
Nil
news:kdvulvkrulufkltd1...@4ax.com:
> I can't tell you what fuse you're supposed to have, but it won't
> be a 250V one.
Well, then, how can one tell? The manual says simply, "In the event of
having to replace the MAINS FUSE always use the same type and rating as
marked on the unit's back panel adjacent to the fuse holder. Ensure
that you are fitting the correct fuse for the voltage in your country."
The power info printed near the fuse holder says "110V; VAC ~50/60 Hz;
380 VA (3A @ 115V)" and "T3.15A @ 230V; T6.3A @ 115V; Mains Input".
> If that amp didn't have a fuse in it, then it sounds like you got
> a piece of shit to me. I'd leave them negative feedback if
> they're not willing to refund your money.
This may be, but I'm happy to spend $2.50 on a few fuses to find out
for sure before I go through the hassle of sending is back.
Tony Hwang
That is the power amp consumes(380VA). In rush current is higher.
I'd put in 6 Amp slow blow type. If it still blows then time to
look for the cause.
Good luck,
Tony
FRETBUZZ
good luck Nil... I think that's a great amp you've won
"Nil" <redn...@lycos.com> wrote in message
news:Xns93F2A1E8...@204.127.204.17...
Brian Running
> > voltage spec printed on the back of the amp says "110V; VAC ~50/60 Hz;
> > 380 VA (3A @ 115V)", so I bought what I though was the closest thing:
> > 4-Amp, 125-Volt fast acting fuses.
> >
> Slow blow fuses are probably what you need. When the amp powers up
> there's a big transient current draw.
>
> The next part is a guess, but I think you'd want a 1.5A 250V fuse,
> since the number quoted 380 VA (volt-amps). A 1.5A 250V fuse works
> out to 375 VA, at least in my simplistic way of thinking about it.
I think you're right about the slow-blow. The analysis of the volt-amp bit
is a little off, I think. If you plug the amp into a 115-Volt outlet, then
that amp is going to get 115V, no matter what the rating of the fuse is.
The rating of the fuse is just that -- it's a rating of the voltage the fuse
can handle. If you put a 250V fuse into a 115V circuit, that doesn't mean
you've cut the current requirement of the amp in half. It's current that
melts the fuse wire, not the voltage, and 3 Amps is 3 Amps, regardless of
the voltage. So, I think you'd need a 3-Amp slow blow fuse, and it doesn't
matter if it's rated 115V or 250V, as long as it's a minimum of 115V. I'd
probably want the 250V, though. Just because. Where's Todd? Todd, get in
here, you're the expert on this stuff.
Nil
news:4yL7b.293$7a2.288@pd7tw1no:
> That is the power amp consumes(380VA). In rush current is higher.
> I'd put in 6 Amp slow blow type. If it still blows then time to
> look for the cause.
Would that be a 125V or 250V fuse? There's a legend near the fuse
holder that I neglected to mention the first time around, "T3.15A @
230V; T6.3A @ 115V; Mains Input" - could this be the fuse
specification?
Chris Berry
supply.
AH 150, AH 250 - 4A
AH 500 - 10A
Here's who sent me the schematic:
Robert Perales
Trace Elliot, Gibson Goldtone,
Gibson Super Goldtone
Parts Sales/Service Representative
1-800-544-2766 x 208
He can probably tell you straight off.
cb
Tony Hwang
Nil wrote:
> On 10 Sep 2003, PMG <avo...@comcast.net> wrote in
> news:kdvulvkrulufkltd1...@4ax.com:
>
>
>>I can't tell you what fuse you're supposed to have, but it won't
>>be a 250V one.
>
>
> Well, then, how can one tell? The manual says simply, "In the event of
> having to replace the MAINS FUSE always use the same type and rating as
> marked on the unit's back panel adjacent to the fuse holder. Ensure
> that you are fitting the correct fuse for the voltage in your country."
>
> The power info printed near the fuse holder says "110V; VAC ~50/60 Hz;
> 380 VA (3A @ 115V)" and "T3.15A @ 230V; T6.3A @ 115V; Mains Input".
Hi,
There it is. T type(slow blow, whatever shape it is) 6.3 Amp @ 115V.
You got it there. So I'd put in 6, 7 or 8 Amp slow blow fuse. What you
put in is too small. Can't stand in rush current.
Tony
Brian Running
> > I'd put in 6 Amp slow blow type. If it still blows then time to
> > look for the cause.
>
> Would that be a 125V or 250V fuse? There's a legend near the fuse
> holder that I neglected to mention the first time around, "T3.15A @
> 230V; T6.3A @ 115V; Mains Input" - could this be the fuse > specification?
I think you're on it, now. The 115V current draw will be double that of the
230V draw -- is it switchable for 115V/230V service? If you're plugging
into a 115V outlet, it looks like you want a 6.3-Amp slo-blo, which is a
common size.
Nil
in news:bQL7b.881$ev2.6...@newssrv26.news.prodigy.com:
> I think you're on it, now. The 115V current draw will be double
> that of the 230V draw -- is it switchable for 115V/230V service?
> If you're plugging into a 115V outlet, it looks like you want a
> 6.3-Amp slo-blo, which is a common size.
Cool. I think you're right. It wouldn't have made good sense for them
to not say what kind of fuse to use, so I figured it must be on there
somewhere. I kinda wish they made it a little plainer for a non-tech
like me.
Thanks, everyone for all your help.
Well, it's off to the Ratshack again!
Steve Cowell
> I recently won a Trace Elliot bass amp on ebay, a 300W GP12-SMX. It
> just arrived today. I was disappointed to find that there was no fuse
> in the holder in the back, so off I goes to the Radio Shack.
Was this amp sold in working condition? I'd roast a seller
that didn't include a fuse... what's up with that?
__
Steve
.
RonSonic
The amp is broke. no question.
It should have no problem powering up with a 3A fuse, even a fast blow.
This amp needs service and you were smart to stop feeding it fuses.
Using an over-rated fuse is a bad idea generally, however these are not exactly
precision devices (especially the crap Radio Shack sells) and there really isn't
that much difference between a 3 and 4. (someone will flame me for this). They
exist to prevent fires, not to protect your equipment.
Look at the blown fuses carefully, is the conductor in the middle simply broken
or melted, or has it vaporized and spattered itself all over the inside of the
glass tube.
The voltage rating on fuses - you can use any rating that is higher than the
voltage that will be applied, a 250V will work fine in a 120V circuit.
Ron
RonSonic
>On Wed, 10 Sep 2003 19:23:50 GMT, Nil <redn...@lycos.com> wrote:
>
>>I recently won a Trace Elliot bass amp on ebay, a 300W GP12-SMX. It
>>just arrived today. I was disappointed to find that there was no fuse
>>in the holder in the back, so off I goes to the Radio Shack. The
>>voltage spec printed on the back of the amp says "110V; VAC ~50/60 Hz;
>>380 VA (3A @ 115V)", so I bought what I though was the closest thing:
>>4-Amp, 125-Volt fast acting fuses.
>>
>>Now I find that the fuse blows immediately when I power the unit up. I
>>tried 2 fuses before I decided I'd better stop. My question is, did I
>>get the right fuse? They also had some 250V fuses, and some were the
>>slow-blow type. Do I need a 250 rather than a 125? Do I need a Slow-
>>Blow, rather than the quick-action one? Am I in trouble for getting a
>>4-amp rather than 3-amp (They didn't have any 125V 3A, but they might
>>have some 250V 3A.)
>>
>>I need to decide if the amp is defective or not.
>
>Just about any hardware store has a better selection of fuses than
>Radio Shack.
>
>I can't tell you what fuse you're supposed to have, but it won't be a
>250V one.
The 250 is PERFECT for this application. Please see my other posts. Yeah, I know
I'm a fucking crank about this, but it is true. The only important factor in the
voltage rating is that it is greater than the applied voltage.
>If that amp didn't have a fuse in it, then it sounds like you got a
>piece of shit to me. I'd leave them negative feedback if they're not
>willing to refund your money.
They sold him a broke amp. Plain and simple.
Ron
RonSonic
<gregory...@sbcglobal.net> wrote:
>
>
>Nil wrote:
>> I recently won a Trace Elliot bass amp on ebay, a 300W GP12-SMX. It
>> just arrived today. I was disappointed to find that there was no fuse
>> in the holder in the back, so off I goes to the Radio Shack. The
>> voltage spec printed on the back of the amp says "110V; VAC ~50/60 Hz;
>> 380 VA (3A @ 115V)", so I bought what I though was the closest thing:
>> 4-Amp, 125-Volt fast acting fuses.
>>
>> Now I find that the fuse blows immediately when I power the unit up. I
>> tried 2 fuses before I decided I'd better stop. My question is, did I
>> get the right fuse? They also had some 250V fuses, and some were the
>> slow-blow type. Do I need a 250 rather than a 125? Do I need a Slow-
>> Blow, rather than the quick-action one? Am I in trouble for getting a
>> 4-amp rather than 3-amp (They didn't have any 125V 3A, but they might
>> have some 250V 3A.)
>>
>> I need to decide if the amp is defective or not.
>
>Slow blow fuses are probably what you need. When the amp powers up
>there's a big transient current draw.
True, but his use of a 4A fuse will offset this.
>The next part is a guess, but I think you'd want a 1.5A 250V fuse,
>since the number quoted 380 VA (volt-amps). A 1.5A 250V fuse works
>out to 375 VA, at least in my simplistic way of thinking about it.
WRONG. No VA's involved. Not that you are over simplifying, but you are over
complicating. There is the possibility that once a fuse has blown that an arc
might still jump internally across the gap. A 24V fuse might allow 120AC to arc
through it, never seen it, but that is the concern.
That is all there is to the voltage rating.
Ron
Todd H.
> I recently won a Trace Elliot bass amp on ebay, a 300W GP12-SMX. It
> just arrived today. I was disappointed to find that there was no fuse
> in the holder in the back, so off I goes to the Radio Shack. The
> voltage spec printed on the back of the amp says "110V; VAC ~50/60 Hz;
> 380 VA (3A @ 115V)", so I bought what I though was the closest thing:
> 4-Amp, 125-Volt fast acting fuses.
Whoa. You replaced a 3A fuse with a 4A. Bad. You can safely go
below 3A (too far below it might blow in normal operation), but don't
go above!
Your fuse can handle 125V -- that's good. Having a higher rated
voltage is ok, but current should match or be lower, otherwise you've
just installed a fuse that will let more current into your device than
it's designed to withstand.
> Now I find that the fuse blows immediately when I power the unit up. I
> tried 2 fuses before I decided I'd better stop. My question is, did I
> get the right fuse?
No. But clearly if you're blowing a fuse that 133% of what you should
have, you've got problems.
> They also had some 250V fuses, and some were the slow-blow type. Do
> I need a 250 rather than a 125? Do I need a Slow- Blow, rather than
> the quick-action one? Am I in trouble for getting a 4-amp rather
> than 3-amp (They didn't have any 125V 3A, but they might have some
> 250V 3A.)
>
> I need to decide if the amp is defective or not.
The amp is VERY defective. Blown/shorted output transistors are a
likely cause.
--
/"\ ASCII Ribbon Campaign | Todd H
\ / | http://www.toddh.net/
X Promoting good netiquette | http://triplethreatband.com/
/ \ http://www.toddh.net/netiquette/ | "4 lines suffice."
Tony Hwang
Hi,
Not only voltages, high current as well. There is such a fuse rated like
48V DC, 200 Amp, literally piece of metal enclosed in a non-flammable
tube with fine sand filled.
Tony
Alun P
warranty and service on Trace gear here in UK.
Look at his web site: www.gmaudio.co.uk
He can offer advice, parts, schematics etc.
An E mail to him could resolve your problem with absolute accuracy.
--
AlunP
www.jurassica.org
alun.p...@NOSPAMblueyonder.co.uk
"Nil" <redn...@lycos.com> wrote in message
news:Xns93F29CA0...@63.240.76.16...
Mr Krinkle
> I just noticed some more verbiage on the amp that might be pertinant:
> "T3.15A @ 230V; T6.3A @ 115V; Mains Input".
>
> Does that change anything, or is it still clear that I need a 1.5A 250V
> fuse?
You need a 6.3A Slo-Blo (slow-blow, whatever) fuse. The voltage rating on
the fuse is not important (preferably high voltage).
Nil
in news:EhT7b.2757$bo3....@news-binary.blueyonder.co.uk:
> You could well contact Gavin Maclachlan of GM AUDIO who carries
> out all warranty and service on Trace gear here in UK.
>
> Look at his web site: www.gmaudio.co.uk
I did, and he responded very quickly to confirm that what I need is a
6.3A slo-blo fuse. Thanks for the suggestion.
Nigel Goodwin
<redn...@lycos.com> writes
Sorry for the slow reply, but yesterday was my day off :-).
From the specifications you read from the back you require (as stated
above) a 6.3A Anti-Surge fuse (normally labelled T6.3A).
The main requirement for it been anti-surge is the switch on current
drawn by the transformer, it would certainly blow a 3A fast-blow on
switch on, and a 6.3A fast-blow probably wouldn't stand it either - if
it did manage it once, there's no guarantee it wouldn't blow the next
time.
Even with anti-surge fuses large amplifiers usually have soft-start
circuits, this limits the initial surge and then connects the
transformer fully to the mains.
One extra point, the switch on surge is MUCH!!! greater with toroidal
transformers - the old square transformers don't usually require
soft-start circuits.
--
Nigel Goodwin
C.Farmer Ltd.
Matlock
Nil
news:6QmNCXCIvZY$Ew...@cfarmerltd.co.uk:
> One extra point, the switch on surge is MUCH!!! greater with
> toroidal transformers - the old square transformers don't usually
> require soft-start circuits.
Sounds like you know this already, but this Trace-Elliot amp has a
toroidal transformer.
I appreciate everyone's advice on this. Unfortunately, the thing keeps
blowing fuses, no matter what the value, so it's plain that there is a
serious problem with it. I am trying to get this resolved with the
seller, but I have bad feeling that I may end up getting screwed. If so
this will be my first ebay transaction gone sour - I've been lucky so
far.
Greg Sz
> I recently won a Trace Elliot bass amp on ebay, a 300W GP12-SMX. It
> just arrived today. I was disappointed to find that there was no fuse
> in the holder in the back, so off I goes to the Radio Shack. The
> voltage spec printed on the back of the amp says "110V; VAC ~50/60 Hz;
> 380 VA (3A @ 115V)", so I bought what I though was the closest thing:
> 4-Amp, 125-Volt fast acting fuses.
This is wrong at he power supply you mus use low fuses.
Fas fuses you use elsewhere in the circuit.
The surge of current charging power supply caps blows the fuses easily.
Value of fuses blow cureent should be specified somewhere.
Not the regular power consumption. Anyway the value you gave seems mor or
less correct.
Juz use slow ones.
> I need to decide if the amp is defective or not.
Connect speaker and better turn all volume, gain, master ... whaetever
buttons to the minimum.
If blows slow acting fuses it would be defective.
Good luck
greg
Greg Sz
Exactly.
T is for delayed action fuse