laney LX120....120watts....Really.

[J M Fahey]

yep.....C5 was shorting so took it of the board and tested again..shorting .

Ok: one of the suspects confessed .
You should have replaced it and re-tested, I guess everything would have been fine.
ONLY if still measuring a short (unlikely although not imposible) continue with:

Removed Q1, lifted one side of D4 removed TS8 (MPSA42) . Junction-tested a new MPSA42 (6 ways) soldered it in, tested again, all was fine but i then had a junction volt-drop cross the emitter/collector one way (cant remember which) removed the little bugger again, re-checked it and it was fine...agghhhhhhhh..how is that possible as the emitter was isolated !!!!!!. lol....and now one of the solder pads on TS8 come away (ok...I can get round that)...aghhhhh.lol
I'm gona leave it now until tomorrow.

Remember: the amplifier is a system, it must be tested functionally, it does not pay to pull all parts and check them "just in case".
Pulling parts hurts them and the board, only done if really necessary.

[RODNEY]

Thank you thank you thank you, on the way to a full repair. Getting -9.5V at the junction of C5 D4 and TS8 and it's now blasting out. Not gona fit the old 2N3819 (Q1) as i don't know how to test it (as it's a JFET), i'll wait for a new one (and compare both of them, just for my interest really) and just put up with the power-on thump for now.
I was very apprehensive about messing around inside the LX as it was "working" to a degree and the having to work on it while is was powered up. I have repaired an amp before, the carlsbro GLX150 about this time last year (there is a thread somewhere on here about it) but it was completely dead so I had nothing to loose.
I have learnt so much during this thread and I wana thank you all for the time you've given to guide me through the fault finding.
Again, thank you. Rod.