Polytone Minibrute II - Problem
Darryl Noda
used them. I purchased one on e-Bay a couple years ago, and
unfortunately, when it arrived, it had a serious "popping" sound when
the guitar was plugged into either channel. I took it to the local
repair guy who supposedly fixed it. I played it a couple times and
then put it on a shelf in my garage for the last couple of years. It
is quite possible the original problem was never solved but I was so
bummed about getting taken on e-Bay, I decided to shelve it for a
while.
Last weekend, we played a gig and I didn't feel like lugging my
JC-120, so I decided to grab the Polytone instead. From the first
tune to the last, the amp was popping like crazy. It mostly pops when
I comp chords and rarely pops on single note stuff. It's almost like
it builds up a charge and the suddenly releases, creating a fairly
loud pop. Between songs, I switched the cord from the high input to
the low input. It still popped, but not nearly as much.
Has anyone else had this kind of symptom with a Polytone, and if so,
does this symptom sound indicative of a typical Polytone problem? I
had heard that Polytones are notorious for having faulty reverb units,
so I'm just wondering if the symptom I have described might also be a
typical problem with some other part of the amp.
GregD/oasysco
news:91639c88.04082...@posting.google.com:
I cant speak to exactly what your problem is, but Polytone usually have
the preamp or power amp section on the top and the other on the bottom.
Additionally, the reverb "send", I believe, is typically attached in a
bundle of wires that "plug" into the top chassis. That plug or the
wiresin the bundle can develop a short which can disable the reverb,
replacing it with a nasty hum. As for the popping, I haven't had that
problem with the two PT's I've owned, but it sounds like possibly an
intermittent short and with PT's design of splitting out the pre/power
amp sections, I'd think you'd need a schematic for your tech to work on
the thing.
Greg
Steve
a problem.
Beyond that, they're usually cheap to fix by a tech visit, in my experience.
-SteveYetter-
Chrome!Hat
Can you narrow it down to either channel or is it on both? Likewise, can you
run the pre-amp out to see if it's in the amp or pre-amp wiring? Also, does
it happen on headphones?
My MB2 has never done this, BTW.
"Darryl Noda" <dhn...@sbcglobal.net> wrote in message
news:91639c88.04082...@posting.google.com...
Don Judy
played it started sounding more like a speaker problem.
dj
"Chrome!Hat" <Rg@storm dot. ca> wrote in message
news:cgqn98$5vm$1...@news.storm.ca...
Pt
wrote:
>I haven't had that
>problem with the two PT's I've owned.
Eeek!
You mean there's 2 of me?
I don't mind being used but I don't like being owned.
Pt
Pt
When it discharges it will cause a pop.
This is typical in older amps.
It may need a cap job.
Pt
EHHackney
right. It turns out that on the jack that connected the preamp (above) cable
to the power amp (below) the power amp had been overtightened and the threads
were stripped, so there was not a solid ground connection. That problem was
more like static/rattle when I played loud.
Another problem I have had (probobly doesn't apply here) is when I would do
rapid stroking across the strings there was a static noise. That turned out to
be static electricity from dragging my finger on the pickguard. I solved that
by covering that part of the pickguard with a piece of transparent tape.
Good luck solving the problem,
Hack
--//--
Darryl Noda
It does occur through both channels although it seems to happen more
through the "hi" channel than through the "low" channel.
It sounds like a capacitor more than a speaker to me. I did listen
through headphones and found the problems still exists.
I decided not to pussy foot around and ended up taking it to my local
repair guy today. He's got a 3 week back log, so it might be a while
before I find out what's going on.
Part of the reason for posting this question was that I was hoping to
go to the repair shop armed with a little knowledge. However,
hopefully he'll be able to find the problem quickly and easily enough.
I'll post the outcome (if anyone is interested to hear) when I get the
amp back.
Justin Otto
> I'll post the outcome (if anyone is interested to hear) when I get the amp
> back.
Thank you. That would be appreciated.
J.
art144
Polytone replaced the pot and haven't had the problem since.
"Darryl Noda" <dhn...@sbcglobal.net> wrote in message
news:91639c88.04082...@posting.google.com...
Darryl Noda
of you have had a similar (Polytone) amp problem. Here is a follow up
on my saga:
Got a call from the repair guy today. He said he couldn't find a
problem with the amp. Went down to the shop to try and demonstrate
the problem. Once I got it to make the popping sound, he immediately
identified it as a problem with the speaker - probably a short some
where in the speaker assembly. I continued to play the guitar through
the amp; he tapped it on top of the cabinet and that coaxed more
popping. Again, he concluded that it must be the speaker. He
recommends replacing the speaker however he's leaving for vacation
this weekend, so he won't be able to do the job until October.
Couple more questions:
1. If it is the speaker, wouldn't it make sense to inspect the
speaker first, to see if there is a loose wire or bad solder job some
where?
2. Is inspecting a speaker for a loose connection or short, a simple
enough task for a novice to perform?
3. In the event the speaker must be replaced, any suggestions on what
I should replace it with? Same exact speaker? Or is there another
after market speaker that people typically use as a replacement to the
stock speaker in a Polytone?
If the first two points are easy for a novice, I may go tomorrow to
get my amp. That gives me two weeks to dink around with it. If I
can't resolve the problem I could always take it back when the repair
guy returns from vacation.
NT
don't like how it sounds in the first place and want to experiment with
others.
-NT
"Darryl Noda" <dhn...@sbcglobal.net> wrote in message
news:91639c88.04091...@posting.google.com...
Kent Burnside
ohms, which really limits your choices. I put in a Weber VST, and it
was a big improvement over the original. (IIRC, the 4-ohm model was a
special order, but there was no extra charge.)
One caveat: Once I tightened down the screws that held the speaker in
place the amp produced a weird distortion. I backed off the screws
slightly and the noise went away; apparently overtightening of the
screws was the problem. I added a felt washer under each screw head
and now everything's fine.
Good luck.
Kent Burnside
dhn...@sbcglobal.net (Darryl Noda) wrote in message news:<91639c88.04091...@posting.google.com>...
Joe Finn
I've never had a speaker do that popping noise thing. If you suspect the
speaker simply run the amp through another speaker that you know to be good.
If the popping stops then you have found your problem. I suspect the speaker
is good. you could also run another signal source through the suspected
speaker and listen for popping.
I think your problem is a bad filter cap.
If you do replace the speaker in a MBII use an exact replacement. It is
necessary on this model to remove the other components in the cabinet before
accessing the speaker. There is very little clearance. Replace the
components in the reverse order of removal. On the last MBII I did it was
necessary to leave the speaker nuts loose to get the amp and preamp into the
box. Believe me, it's a tight squeeze. .......joe
P.S. The repair guy you visited initially said he couldn't find a problem
with the amp??? This is a red flag. Take it elsewhere next time. Good
luck.
--
Visit me on the web www.joefinn.net
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Darryl Noda
dhn...@sbcglobal.net (Darryl Noda) wrote in message news:<91639c88.04091...@posting.google.com>...
Mark Guest
news:414af...@corp.newsgroups.com...
>
> I've never had a speaker do that popping noise thing. If you suspect the
> speaker simply run the amp through another speaker that you know to be
good.
> If the popping stops then you have found your problem. I suspect the
speaker
> is good. you could also run another signal source through the suspected
> speaker and listen for popping.
>
> I think your problem is a bad filter cap.
>
> If you do replace the speaker in a MBII use an exact replacement. It is
> necessary on this model to remove the other components in the cabinet
before
> accessing the speaker. There is very little clearance. Replace the
> components in the reverse order of removal. On the last MBII I did it was
> necessary to leave the speaker nuts loose to get the amp and preamp into
the
> box. Believe me, it's a tight squeeze. .......joe
>
> P.S. The repair guy you visited initially said he couldn't find a problem
> with the amp??? This is a red flag. Take it elsewhere next time. Good
> luck.
>
One of the Ptones that I owned had a problem due to cold solder joints. I've
heard others complain of the same thing. I agree with Joe's last
comment...try some other repairman.
--
Mark Guest
Mark at MarkGuest.net
www.MarkGuest.net
Stan Fong
>
> I've never had a speaker do that popping noise thing. If you suspect the
> speaker simply run the amp through another speaker that you know to be good.
> If the popping stops then you have found your problem. I suspect the speaker
> is good. you could also run another signal source through the suspected
> speaker and listen for popping.
>
> I think your problem is a bad filter cap.
>
> If you do replace the speaker in a MBII use an exact replacement. It is
> necessary on this model to remove the other components in the cabinet before
> accessing the speaker. There is very little clearance. Replace the
> components in the reverse order of removal. On the last MBII I did it was
> necessary to leave the speaker nuts loose to get the amp and preamp into the
> box. Believe me, it's a tight squeeze. .......joe
>
> P.S. The repair guy you visited initially said he couldn't find a problem
> with the amp??? This is a red flag. Take it elsewhere next time. Good
> luck.
>
I agree with Joe. I've never heard of a speaker causing itself to make
a popping sound. I don't think your problem is from the speaker.
Loose connections are easy to detect. Tapping on the amp and causing
it to pop sounds more like a bad connection. Inspect the wires and
speaker terminals. I'd get a second opinion from another repairman if
you can't find the problem yourself.
Stan
Max Leggett
>Loose connections are easy to detect. Tapping on the amp and causing
>it to pop sounds more like a bad connection. Inspect the wires and
>speaker terminals. I'd get a second opinion from another repairman if
>you can't find the problem yourself.
My amp was making funny noises, which got me cheesed orf, and I felt
a bit rough after the gig, and sore and achey the next morning, so I
went to see the doctor. He looked at me and said, "How much did you
drink last night?" "Well, I was cheesed about my amp, so I had maybe
10 or 12 gins. Why?" "Well, I've got a diagnosis for you - you're
stupid." "Just one second there, pal. I think I'd like a second
opinion." "Alright - you're ugly, too."
And people think musicians have it easy. I tell ya.
EHHackney
Hack
--//--
Darryl Noda
Thanks all for the advice. As it turns out, I called the repairman
today. He happened to have my amp opened up at the time I called. He
confirmed that the speaker was alright. Now he suspects a loose
connection, bad capacitor or poor solder job, as some of you have also
mentioned. He said he wasn't familiar with Polytones and wasn't sure
how available parts are.
I picked up the amp today. I'll have to check and see if there are
any repair people in the area that are familiar with Polytones. I may
even open it up myself to see if there are any glaring bad
connections.
Thanks again for all your advice.
Best regards,
Darryl
EHHackney
top) to the power amp (below). When the jack on the power amp had been
installed, it had been overtightened, and the threads were stripped, so there
wasn't a solid ground. I happened across a really good repairman who picked it
up first thing.
BTW: The first time I tried to have this fixed, I DIDN"T have a good
repairman. He charged me $60 to "rebias" the amp, whatever that means, and the
problem came back.
Hack
--//--
Darryl Noda
Thanks again to all who have offered comments and advice.
So, any recommendations for a good Polytone amp repairman in the San
Francisco Bay Area?
Best regards,
Joe Finn
> As it turns out, I called the repairman
> today. He happened to have my amp opened up at the time I called. He
> confirmed that the speaker was alright. Now he suspects a loose
> connection, bad capacitor or poor solder job, as some of you have also
> mentioned. He said he wasn't familiar with Polytones and wasn't sure
> how available parts are.
Darryl: Your repairman is an idiot. One needn't be a board certified,
factory trained polytone technician to find a bad cap or a busted solder
joint.
> I picked up the amp today.
Best move you could have made!! good luck !! ........joe
dhn...@sbcglobal.net
Polytone amps. He found the problem - it appeared to be a bad solder
job on the main board of the amplifier. He commented that the solder
job looked pretty sloppy. I picked the amp up yesterday and played it
for quite a while last night. He seems to have successfully eliminated
the pop. Just hope the rest of the unit holds together for a while.
It seems like that amp has spent more time in the shop than on the job.
Thanks again for all your suggestions and feedback.
Michael L Kankiewicz
I took a used MBII to a very good tube amp tech unfamiliar with PT, to
have the pots cleaned. He told me he was very impressed by how good the
workmanship was inside.
MK
Joe Finn
<dhn...@sbcglobal.net> wrote in message
news:1106148801....@f14g2000cwb.googlegroups.com...
Was this a new amp? My assumption being that a bad solder joint resulting in
the problem you describe would have been evident immediately.
If you got the amp was the problem there when you got it?
Either way I'll bet you're glad it works now. .........joe
dhn...@sbcglobal.net
plugged it in and found the pop. The amp was produced in 1999 and I
purchased it in 2001 (I think). Its appearance looked very new, but
the pop was evident the moment I plugged it in. Took it to a local
repair guy who couldn't figure it out. Called Polytone, but got no
where. Posted a thread on this news group last Fall. Found a repair
guy in a neighboring city who had repaired Polytones before and who was
recommended by a friend. Thought I'd post the "rest of the story"
since I finally got it repaired.
Joe Finn
<dhn...@sbcglobal.net> wrote in message
news:1106154473.7...@f14g2000cwb.googlegroups.com...
I remember your original post probably because I've been using Polytones all
these years. I'm not surprised that the pop was noticed immediately. It
didn't seem like the sort of problem that would crop up later on.
Don't forget to post ebay feedback on the seller's defective item.
I hope it works from now on. Good luck, and thanks!! .......joe
dhn...@sbcglobal.net
I wish. It was my first ever e-Bay purchase. When I unboxed the item,
it looked brand new - I was thrilled. Turned it on, no weird hiss.
Plugged in and played - no problem (at least in the first few minutes).
Gave the guy positive feedback. Went back to testing it and about 10
minutes into using it - snap, crackle, pop. Two things I will no
longer buy on e-Bay: guitars and amps. I'm sure there are other
things too, but those two are at the top of the list.
LarryV
solder joint could have manifested symptoms as a result of vibration or
whatever during shipping. Whenever you ship an amp, you run the risk
of developing problems due to rough handling, vibration or whatever. I
think it's hard to place blame on the original owner when the issue is
traced to a bad solder joint as he may have had problems, or may not
have had any problems.