I got a new amp today.

[GoldenVulture]

Re: I got a new amp today.

Sorry I missed the pink ha ha.
[ATTACH=CONFIG]97081[/ATTACH]

Thanks but there's another two I think to the left under the output module board. I need to know what they are. That screw in the middle of the chip holds the modules in . Undo that if you can and lift up the module. you could even unplug it too.

Chances are they are also .1 Ohm resistors which sit on the outputs of the modules. If they're not replaced it will most likely blow again. They're linked to the protection circuitry as well as the output modules.
I don't know if you can read this but if you look at output 1 and output 2 , there are 3 resistors connected to them labelled OR1, that's the ceramic resistors. [ OR1 = .1 Ohms ]

Available modules from England.
- https://www.proaudioservice.co.uk/pr...odule-tda7293/ -

[80's_Metal]

Re: I got a new amp today.

So here's what specifically happened when it blew.

I had decided to try my e1 legendary amps in the effects loop.
As I was working with the levels and whatnot on the amp 1 clean channel, I reached around the back and there's a switch/button to add db or -db in the effects loop.
I pushed that button in and snap! I saw the spark from the fuse go, and smelled a burning smell.

Went to hardware store replaced the fuse, (amp apart now on the bench) and plugged it back in and tried to power it on.... Bzzz fuse snapped again and smoke from the two ic units I am pointing to in pix.

Don't know if that tells you anything but that's what happened.

[80's_Metal]

Re: I got a new amp today.

Sorry I missed the pink ha ha.

[GoldenVulture]

Re: I got a new amp today.

Sorry I wasn't clearer about that. Those BIG ceramic resistors on the board underneath the Module board that I circled in the pink. If you identify them for me I may give some advice regarding them and the module boards. They may be something that other people are overlooking when trying to repair these amps.

You may be able to actually order those boards but it's probably price prohibitive. Also for the above possibility , drop in and replace might not quite work.





These are actually 10 Nanofarad capacitors.

[80's_Metal]

Re: I got a new amp today.

Dear Marshall Amplification, I need 4 of these stat:


And a couple fuses too

[80's_Metal]

Re: I got a new amp today.

Too bad I can't just order 4 whole boards and just screw em on and plug em in. Ten minute job. No soldering.

[80's_Metal]

Re: I got a new amp today.

If you could see what those ceramic resistors are on the circuit board and their part number on the board that would help.

These help? Or what am I looking for.

[GoldenVulture]

Re: I got a new amp today.

Here's the other thread I found. It has a few partial bits of the circuit linked. Posts #25 & #26

- https://music-electronics-forum.com/...ead.php?t=3873 -
If you could see what those ceramic resistors are on the circuit board and their part number on the board that would help.

[PFDarkside]

Re: I got a new amp today.

The previous owner probably had them go up in smoke and replaced them once before. Good luck!

[GoldenVulture]

Re: I got a new amp today.

I stumbled upon this thread in my searching


https://music-electronics-forum.com/...ead.php?t=5143

That's one of the threads I found . It's got the correct chip type listed in it.

[GoldenVulture]

Re: I got a new amp today.

It looks to me like those screws holding those onto the heat sinks have been out a time or two before?

And the heat grease is in 2 different colors too. Ha ha

Yes and they've heaped on way more grease than they need. It really only needs to be a thin layer between the back of the chip and the heat sink.


Also that chip is a replacement / equivalent type. That's what NTE make. They're usuall a bit more expensive too.
According to one of the threads I found it is a TDA7293V.

[80's_Metal]

Re: I got a new amp today.

It looks to me like those screws holding those onto the heat sinks have been out a time or two before?

And the heat grease is in 2 different colors too. Ha ha

[80's_Metal]

Re: I got a new amp today.

I stumbled upon this thread in my searching

https://music-electronics-forum.com/showthread.php?t=5143

[80's_Metal]

Re: I got a new amp today.

[GoldenVulture]

Re: I got a new amp today.

Everything I've read about this amps shortcomings points to the 4 power modules... I'm not an amp tech guru yet... But I took pictures of where the smoke came from if anyone else is.

[ATTACH=CONFIG]97047[/ATTACH]
[ATTACH=CONFIG]97048[/ATTACH]

Ok. It looks like these are notorious for blowing up. Bad circuit design apparently. They blow up those chips your pointing at in those pics. They run in those pairs and if even just one goes , both need replacing. The chips themselves are not expensive but the repair process is really touchy, as is the amp operation because of the design. It appears if you have it on [ in working state ] , turn it off and change speakers without the power draining right out first , they'll blow up. Also very easy to short the outputs.

Apart from changing the chips, those big ceramic resistors in front of the modules there will probably need to be replaced.

I've dug up a couple of trouble shooting/ repair threads. Let me check them out and I'll get back to you.

If you could get me a good close up pic of that module , it would be appreciated.