Machine Gun Amps
Strange amp problems

These are some strange problems that I have seen or tech friends of mine have seen. These are probably not things that you should check for, but be aware that strange things do happen!

Paul C:
1. "Had an AC30 reissue on my bench that was blowing the mains. Circuit mounting posts were drilled right into the heater traces. What I don't get is how the amp worked for 3 months before the guy brought it in! Not an amp story, but I just finished working on a korg 01w synth. Cust. had plugged a power amp output into the synth's output! Flames shot out of the Vol.Fader! The amazing thing is all I had to do was change the vol. fader - nothing else was damaged!"
(AR: Shorts in the filament supply will cause strange problems folks! This amp that Paul is describing should have never worked!)

2. "Last year I had a peavey CS800 come in. When I got the lid off a mouse jumped out of it! She took off - I took off! Scared the piss out of me! The sad part is she had a nest of babies in there. The owner of the store grabbed the vacuum and sucked 'em up! I felt REALLY bad for the little guys..."
(AR: Mice don't help much unless they are on one of those little runners generating electricity! Would that be enough to run a high power PA amp like this?)

3. "I've got one more! The old store I used to work at had a deal with the grad school system here in Nashville. At the end of each year I got about 50 Rhodes pianos to fix. I found porno mags, rubbers, cigarettes etc... inside of 'em. All from 6th graders. Hummmmm."
(AR: Those things don't help tone too much I would imagine. Kids these days... Why did they need all this stuff if they had Rhodes pianos to play?)


Keith M:
1. "Had a brown Super in that sounded great at low volumes but when pushed past 7 for a couple of minutes, lost volume and Hummed like crazy. the coupling cap from the second gain stage and one
of the bias filter caps were not soldered in . Funny thing is the owner had never had it serviced
before and the caps matched all the other original caps."
(AR: A Fender that someone forgot to solder in components? This tugs at my heart!)

2. "On another amp, brought in because it made funny noises, the nuts for the power tx had all come off and the transformer, with the longest leads I've ever seen, dropped through one of the speaker
cones."
(AR: Speakers don't work too good with transformers sticking through them.)


Tom:
"One of my earliest troubleshooting experiences was a customer who brought in a Woodson PA
head, solid state. It had fried a chunk of circuit board without blowing the fuse which was soldered in place internally in the unit. I pulled the thing apart and discovered that the fuse wasn't the 2 amp job
the schematic called for but a 10 amp fuse! It apparently came from the factory that way. Woodson
had a 'lifetime guarantee' so the customer was just out the hassle of being without his PA head for
two weeks. A few months later, Woodson folded up their tents...I wonder why?"
(AR: Uhh, that's not too hard to figure out. You'd be surprised at how many people do stick fuses in the socket that are way too big for what the application is. A fuse is meant to blow if too much current is put to it. Putting in a too big fuse will blow things up, sometimes in a dramatic way such as Tom described!)

Mark N:
"----------> andy...this is no shit, ok?

guy brings in a dead mint fmi b/f pro reverb....except the baffle is gone. he's made his own with cdx
floor underlay plywood [ugh...tools in the hands of idiots]& badly attached reissue grille cloth. "can
you 'fix' it?", he asks....well, sure....but what about electrolytics, et. al. inside? want them looked at /
replaced?

so i get the "go ahead" to do a full "once over". believe me, in my professional judgment, this chassis
had never been pulled. so i pull it.

ladies & gentlemen.................chicken bones!!! no shit! the chassis if full of chicken bones!!! either
someone in c.1966 is eating at his work station, or some kind of weird, evil, voodoo shit's been going
on....either way, these looked like chicken bones!!!! what can i say?????

i photograph just about every amp that comes across my bench [andy, remember the super twin
reverb pics that scared you shitless?], but these bones flipped me out & i plum forgot to "capture the
moment"...but it did happen....just that way

thought you'd enjoy.....now go write that book!
---> mark n"
(AR: Voodoo? Chicken bones do make the amp sound more like Hendrix. But I'd say that they also are good for suppressing oscillation right? No? How 'bout for drawing Vultures?)


Donner:
"I was checking out this cool Earth 4x10 black vinyl 'tuck and roll' combo, and really liked it, so I decided to really turn it up to make sure it could take a beating and sure enough-blown speaker, bummer but I was really interested in how it was put together and got to looking at the speakers and saw a little stem sticking out of one speaker- pull and its a leaf and another and a third leaf was wedged into the speaker,,,it wasn't blown at all, sounded great in fact,,,,the answer my freinds was blown in the leafs........"
(AR: Earth amps with leaves in them... Does this mean that I'll find a '33 Ford inside a Fender someday?)

Dave Boze:
1. "I'm beginning to think that mouse turds are factory installed, since I find them in about 75% of the amps that come through here.
Brought one into the house 2 years ago, my daughter said, "Hey, look there's Mickey". We turned
and sure enough there was a mouse coming out of the amp. But that's nothing....."
(AR: Mickey Mouse picked a good, albeit loud,  place to live. Nothing is right though, get a load of this next one!)

2. "My favorite was I got a call, "Can you fix an amp for me, has lots wrong and 1 speaker is shot. I
sez, "No prob, I can fix any Fender and I'll get the speaker reconed.

So he shows up and there is a HUGE HOLE in the front of the amp through the grille cloth. I turn
the amp around and look at the speaker (silver Vibrolux reverb). One of the 10's is DESTROYED.
I mean annihilated!
The bell is twisted a million directions and I look close and there are lead beads in the bottom of the
amp. I said, "You weren't kidding when you said the speaker was blown". He sez, "Blown???, I told you it was shot! Shot right through with a 12 gauge shotgun. Somebody got real mad at my
son-in-law who use to own the amp and took a gun to his amp" BANG!!!!

The good part was that I patched the baffle, re-grille clothed it, and put a replacement speaker in it,
tuned the amp and she sounded FABULOUS. Those Fenders take a lickin' and keep on
tickin'!!!!!!!"
(AR: This is a common technique I'll use if I get a really sorry excuse for an amp and I can't fix the amp. I find that 12 gauge with medium weight shot works perfect. Blast a hole in the amp then return it to the owner and say "I don't what happened man. I was testing it out and it made this strange sound... I think you should take this thing to an exorcist instead of an amp fixer..." Works every time. By then they REALLY want a Fender.)


Not a fix it story, but still hilarious from
Mike Shaw:
"This isn't really a fix-it story but... I was in a guitar shop in Illinois a few years back and noticed a
page from a setup manual from a Japanese company that manufactures guitar synths. It was hanging
on the wall in a picture frame. As I was checking it out it I noticed it had a picture of the hex pickup
and how to mount it to the body. It showed the pickup and the mounting screws, but instead of
labeling the screws as "screws" they labeled 'em as "fucks". After I was through laughing I asked the
sales guy what the deal was. He said he asked the company rep the same thing and they responded
that one of the engineers putting the manual together was having a tough time with his Japanese to
English conversions and asked an American sales rep what the American equivalent of "screw" was.
The rep not knowing he was referring to a Screw (the mechanical fastener that is) responded in the
sexual way. And the rest is history (as well as the Japanese engineer I'm sure). This is the absolute
truth - I swear!!"
(AR: Poor guy. Us Americans can be smart asses sometimes huh?)

Now some stuff from me
My stories are nowhere near as funny as the stuff above, but it is strange stuff I've come across when fixing amps.
1. I was playing my project amp one day at normal volume (well for me, full throttle full up to 10). I found that it lost all volume, or at least the guitar wouldn't make any noise. Hmmm. But the amp was still hissing like crazy so I figured it must be a problem somewhere before the volume control. I checked every component and everything was good. I was about to give up for the day and I noticed that the input jacks had broken apart. On Fenders, the input jacks get soldered together, then the assembler would bend them as necessary to get them to go through the holes. Well, this one must have been bent pretty bad, because it broke the solder joint clean through and separated the jacks. It took a destructive kid like me to make it happen. One more unlikely thing for you to check folks.

2. I was playing my Quad Reverb one day (not even full bore, that's pretty loud for a Quad), and I noticed that suddenly no more sound was coming from the amp. I took the chassis out and played it, the sound was coming out of the speaker. I thought that this was going to be one of those horrible oscillation problems that you don't find but keeps coming back at the worst possible time (Murphy's Law guarantees this folks). Anyways, after a few hours of looking and thinking, I noticed that the aluminum shield stapled to the inside of the top of the amp had come down (I should have known, the amp was particularly hard to take out of the cabinet this time! Use your noggin!). It was shorting to the volume control. I nailed it back up and that was it.

3. I have some other not so remarkable stories from customer's amps too. One time I was given a Super Reverb chassis to bring back from the dead (had been blown for years). It had all kinds of strange and stupid mods to the circuit, but thankfully, no holes in the chassis! The power transformer was blown, and I noticed the fuse socket stuffed full of aluminum foil. After looking for a while, I noticed an innocent looking wire going from one leg of the heater circuit to ground. I have no idea why. The modder put this in, for what reason nobody will know. The power transformer was blown of course. Probably because the fuse kept blowing so the "tech" or whoever put aluminum foil in the fuse socket and that was it. The moral of the story? For the people just getting started working on amps, find out why something blows before you replace the blown component! If I had just fixed the mods and put in a new power transformer, I would have run the risk of blowing it!

Sorry about my stories! I'm sure I'll find something as funny as the stuff above one day.


Back to Machine Gun Amps.    To Contents.   To links.  Email me with your wacky story!

All content of this web site © Machine Gun Amps.
All company and product names are presumed trademarks of their respective companies.

Last updated 2/19/2000