Trace Elliot SuperTramp Twin losing power

[Pinchinpete]

I have an old but great sounding Supertramp 100w twin which has been as good as gold for years but now has started to lose power after 15-20 mins and is intermittently playing up.

Its not effected by banging so I assume its not a dry joint or loose connection somewhere and I wondered if it might be the valve in the preamp. The amp goes from playing clear to about 1/4 volume sounding real muddy/ fuzzy

Any thoughts would be most appreciated

Thanks

Pete

[J M Fahey]

Send the signal from its effect send to another amp, and drive its poer amp with signal from another amplifier. At least you'll know where the problem exists.

[Pinchinpete]

Thanks for your response..

Just to make sure I understand...if I route the signal from the effect to another amp and it's OK then this means the pre amp and the valve are fine and the problem is in the power amp?

[oc disorder]

Yes thats what he means.
The effects send comes from the preamp before the power amp so if its a healthy signal there chances are that the fault is in the power amp section.
However with your amp its slightly different as you have 2 independant power amps from what I can gather.
I would assume the speakers are not joined together electrically and each one has its own 2 wires that disappear into the chassis.
(A bit like a stereo hi-fi amp L & R in one chassis)
When trying to diagnose a fault it helps to imagine it in sections.
In a car for example there is electrical ignition - fuel - carburetor or injectors
brakes etc etc. If it won't start obviously its either electrical or fuel related.
With your amp its pre-amp (mono) poweramp 1, poweramp 2, and power supply and maybe speakers but I think you can discount them.
When you have your pre-amp feeding another amplifier you're testing the pre-amp and the part of the power supply that feeds it.
If thats ok then its one of the poweramps or the part of the powersupply that feeds that. Its unlikely that both the power amps have a fault.
But if they both do display faults its more likely to be something they have in
common. As (hopefully) the pre-amp has been previously checked then the next suspect must be the power supply .
So does the preamp fade when plugged into another amp?

[Pinchinpete]

Thanks ...

I have routed through my back up and its fine so I am assuming its the power amp side...you say there are two and I assume that each one feed the each of the two speakers so I have tried with one unplugged and they are both the same.

The sound remind me of the tail off you get when you switch an amp off sort of fades fuzzy if you know what I mean..When I hit the guitar the sound it load not the usual clean sound but dies very quickly as I say like the amp is being switched off.

I am not a tech but am happy to try changing components if something seems obvious like a power supply so any tips appreciated..

Pete

[J M Fahey]

Well, we were all shooting in the dark.
Besides the misleading "Twin" name, the ST (SuperTrampTwin for short) has one power amplifier, but twin speakers.
To add to the confusion, the "power Amp in" is not so.
It still travels through two preamp fets and a Master control.
Reason is to provide a "Presence control" that really isn't so.
How do I know now?
I found the schematic and the user manual.
I must say it's a very peculiar amp, with a ton of Fets , a tube, and (expensive) Mosfet power output.
User Manual: Download Trace Elliot Super Tramp Twin Owner's Manual
Yea, it says "downloading *Peavey* manual", go figure. They don't make it easy, eh?
I'll attach the schematic.

[oc disorder]

Check around the power supply look for any signs of heat (ignoring the
glue goo) also check for anything loose or soldering that needs reflowing.
Its not the master volume perhaps? Does it crackle or make noises when its turned ? You may need a signal (open guitar string ?) going through while you turn it.

Posts cross..um must be going blind "Blind OC Disorder" um cannot spot the tube?

Pinchinpete a picture would help

[J M Fahey]

Hi OCD: it's there, on plain sight, don't you see it?
It's on the back panel, beautifully silk-screened.
It also says Super Tramp Tube...................................
No, I'm kidding (or Trace are?)
There *IS* a Tube version, with stereo "Quad Chorus", whatever that means, and yes, it has two (bipolar) power amps.
There is also a *third* different amp. also called Super Tramp.
It has no tube, and two power amps possible: a TDA1514 chipamp based one and a bipolar Darlington one.
A little bit confusing.
Anyway, I'm posting the tube stereo chorus and the chip/bip version which counts as two.
*Please* don't tell me you have a fifth version !!!!

[Pinchinpete]

Thanks Guys...as I say I am not a tech so looking for an easy answer..I have poked all the usual parts with a screwdriver to see if any response but non cant see any dry joints and the valve lights up...so may just try a new valve ....so its back to me old trusty standby a 1980's Yamaha G50 112 until I can get it fixed..

Anyone know a good tech in in Somerset UK? as I can't seem to find anyone here who will have a look at this...
Just meant to say there's quite a bit of white glue on a section of the circuit broad I haven't got the faintest idea what it is or where its come from it appears that some components were glued to a section of the chassis and this has melted and run onto the board covering a couple of resisters...strange!!

[Pinchinpete]

Hi

Just a quick update I had a tech look at the amp who advised me that the white glue as I called it was the heat sink from the power transistors and these are blown...its not worth the repair as the amp isn't worth what this would cost...seems a shame to waste a nice cab and 2 x 12" celestian speakers so may try a head....any thoughts

[oc disorder]

Hmm would have thought it was worth fixin' !

Maybe he was not familiar with the Hitachi Mosfets which are obsolete
but you can get equivalents for.

Here
Welcome to rswww.com

Hitachi TO-3P 2SJ1058/2SK162 = Magnatec TO-3 BUZ901/BUZ905

N-channel MOSFET,BUZ901 8A 200V
RS Stock No. 841-053 £11.99

P-channel MOSFET,BUZ905 8A 160V
RS Stock No. 841-081 £9.28

NPN Transistor,250V,50mA,BF422
RS Stock No. 508-440 £0.071 (in a packet of 50 ? )

PNP transistor,BF423 0.5A
RS Stock No. 545-0129 £0.15

The diodes and the zener diodes wouldn't cost much.

The white gunk you speak of is heatsink compound and usually goes
between (with an insulating mica washer ) the transistor/mosfet and the heatsink to improve thermal conductivity.

I'de try for another quote in a larger town !

[Pinchinpete]

Thanks...I could probably have a go at this myself as I have dabbled in the past and quite fancy the idea of getting hands on again...I understand to use heatsinks and pretty good with a soldering iron............just as a matter of interest how do you know the value of these components as the schematics just shows them as TR1 -2-3-4 and ZD 1 ect?

[J M Fahey]

Sorry but there's something fishy here.

The amp goes from playing clear to about 1/4 volume sounding real muddy/ fuzzy

and presumably does this every time you turn it on.
That means your transistors are *NOT* blown !!!!!!!
Or at least that they were alive before visiting your tech !
Please confirm that it still behaves as quoted or if the situation changed.

[Pinchinpete]

Funny because just before I took it I tried it, and it went on along with the fault ...poor volume sh*tty sound quality... however he said it blew the fuse when he switched it on and its the power transistors and maybe other components that he would identify when these were replaced.

I am in a tough situation because I do not have enough knowledge to query what he says I assumed he knew what he was doing but someone else has said he's blown those poking around inside with the power on

Anyway I am left with this amp that was my main one and I need something similar fast as all I have is my Yamaha G50 112 and that's doesn't give me the tone I am used to.

I am either going to have a go on this my self and/or replace.....this time I may get all valve as in my youth I had a impact 60 with a cab and an old fender twin reverb and ditched them in for the brand new Yamaha which was the best thing since sliced bread in 1982 and I thought that was the way to go......fool that I am!!!!

My thoughts are to buy the components and have a go as a project because having tried in vain to find someone to repair the thing joined this forum and other sites it's intrigued me feel into finding out a little more so be self sufficient....(any pointers to educational material appreciated)

So I am also thinking about buying either a head and using the supertramp cab or a twin along the lines of a fender reverb or the Vox/Orange 30 valve amps.

[J M Fahey]

someone else has said he's blown those poking around inside with the power on

Agree 100%.
Get your amp back, pay him nothing for the mess he made, if he gets rough (only in that case) tell him you'll file a complaint with the Better Business Bureau or whatever official branch you have there and inform him that a government Lab will check the amp to see what the real cause of the problem was ..... charging him the procedures, plus fines.
All cr*p , of course, but not more than what he's feeding you.
Try to get a nerdy friend that already is comfortable with soldering guns and multimeter, who has already built *something*, even if unrelated to guitar amps.
Don't know where you live, but Awards Session amps (UK), of Sessionette 75 fame, sells a drop-in Mosfet power module which very probably can be mounted in your amp, by soldering only 5 or 6 wires to clearly marked tags. Check their site.
The sound will be 99% that of the original.