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Trace Elliot cuts out after playing for a while

R

rowbi

Mar 31, 2009
6
0
#1
Hi

I'm the lead guitarist in a band, and my bassist is having some issues with his amp, and as I mod a lot of my guitar amps, I thought I'd try to fix it. my problem is that I haven't ever worked on a bass amp, and so I'm posting in the hope that someone knows any common issues that I could check first before just re flowing all the solder joints and looking for poor mounted heatsinks.

The Amp: Trace Elliot 1210 4x10 (or 4x8) combo with GP12 preamp.

THE FAULT EXPLAINED:
Basically the amp works fine (apart from maybe a little hum all the time, but I don't know if that's normal) and after a random length of time (as little as a few minutes up to 90 minutes before the fault starts)... the sound will just cut out. there's no loud pop or anything, the sound just stops. a good bang on the amp or turning it off and on will make it work again but often only for another couple of minutes.

like I said above, I'm thinking dry joint being affected by temp (amp warms up, gap opens further, and sound stops) which may be why it lasts over an hour now in the cold garage we jam in, but may last less time in the summer?!?!

Any help would be great

Regards

Rowbi
 
#3
Obvious place to start is the cooling tunnel. Over time the fan sucks in a lot of air and with that a lot of dust and other crud. Disconnect the amp from the power. Take the lid off and look. Vacuum the heatsinks and make sure the fan is able to turn and is unobstructed. A soft paint brush will aid with the removal of dust. On one of the heatsinks you will see a device that has two terminals. This are usually wired in series with the speakers so that when it gets hot enough it will operate and remove the load until the sinks cool down. Then the speakers are reconnected.

Paul
 
#4
rowbi said:
Hi

I'm the lead guitarist in a band, and my bassist is having some issues with his amp, and as I mod a lot of my guitar amps, I thought I'd try to fix it. my problem is that I haven't ever worked on a bass amp, and so I'm posting in the hope that someone knows any common issues that I could check first before just re flowing all the solder joints and looking for poor mounted heatsinks.

The Amp: Trace Elliot 1210 4x10 (or 4x8) combo with GP12 preamp.

THE FAULT EXPLAINED:
Basically the amp works fine (apart from maybe a little hum all the time, but I don't know if that's normal) and after a random length of time (as little as a few minutes up to 90 minutes before the fault starts)... the sound will just cut out. there's no loud pop or anything, the sound just stops. a good bang on the amp or turning it off and on will make it work again but often only for another couple of minutes.

like I said above, I'm thinking dry joint being affected by temp (amp warms up, gap opens further, and sound stops) which may be why it lasts over an hour now in the cold garage we jam in, but may last less time in the summer?!?!

Any help would be great

Regards

Rowbi
Click to expand...

I think you're right about the joints... Otherwise a bang to the top of the amp shouldn't do anything...
 
#5
BassmanPaul said:
Obvious place to start is the cooling tunnel. Over time the fan sucks in a lot of air and with that a lot of dust and other crud. Disconnect the amp from the power. Take the lid off and look. Vacuum the heatsinks and make sure the fan is able to turn and is unobstructed. A soft paint brush will aid with the removal of dust. On one of the heatsinks you will see a device that has two terminals. This are usually wired in series with the speakers so that when it gets hot enough it will operate and remove the load until the sinks cool down. Then the speakers are reconnected.

Paul
Click to expand...

there's no fan. the only thing I found was the bolt holding the big round transformer was loose, so the transformer could move around.

apart from that it looks very complicated. photos of the inside of the amp here: Link Removed

any clues where to start looking?

also should I be worries about high voltages from those 2 big capacitors?? do I need to drain them like I would in a tube amp??

Cheers

Rowbi
 
#6
Normally the caps will be drained by the output stage.

Try the obvious first. I assume that the power lamp stays lit but the sound goes off. If so replace the speaker fuse, Check the wiring from the fuse to the board and to the output jacks. The wiring from the transformer terminate in the screw block. Undo and reseat the wires and ensure that the screws are tight. The screws in that kind of block always seem to become loose with vibration.

When the sound cuts out can you hear any hum or hiss coming out of the speakers? If there is then your MOSFET power amp and power supply are probably OK and you should look at the preamp board.

Paul
 
#7
cool, sounds like you really know what you're talking about.

I'll try all that and see what happens...

just a thought.... is there any reason why there's the screw block in there?? wouldn't it be better to solder the wires direct??
 
#8
Our Yamaha from 80's? had the same problem for quite some time, didn't occur too often so we didn't care to fix it in time (mostly due financial situation >_>). Lately it shut off completely, the power led wakes up when I turn the power on, some signal goes to the speaker as it silently moves back and forth for a second or so. After that no signal goes through. Does this sound like a blown fuse or something more lethal?
 
#9
putsia said:
Our Yamaha from 80's? had the same problem for quite some time, didn't occur too often so we didn't care to fix it in time (mostly due financial situation >_>). Lately it shut off completely, the power led wakes up when I turn the power on, some signal goes to the speaker as it silently moves back and forth for a second or so. After that no signal goes through. Does this sound like a blown fuse or something more lethal?
Click to expand...

Could possibly be a fuse issue if the power amp supplies are fused. If not it's going to be more serious. you speakers are responding ti instability on power up. You can overtax the excursion limits of your speakers.

Paul
 
#11
thanks for that.

I think I've found the issue. all the jack sockets in the amp seem to have some green-ish corrosion on the surface of the metal parts of the jacks. this seemed to be that the effects loop return jack was really greean and where the pins on the jack touched to make the signal, it seemsd to lose connection.. at least I think. I've cleaned them all up and there's not more issues after a few tests on this one. my only other issue seems to be transformer hum, but I'll post that in a fresh question.
 

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