Solid State Guitar Amp Forum | DIY Guitar Amplifiers

My friend's old SS traynor bloc's led indicates power on but no signal is getting through. The channel switching does not make the led light up on the other channel. I'll check this. Visually all the guts look good and everything is connected. Fuses appear to be good. Capacitors look good. I haven't stuck the meter on it yet. No transformer hum, I'll check this first. Any other suggestions? Poke and tweak here we come. (no safety warning necessary)

Start by checking the speaker , unhook one of its cables and test it with a 9V battery, it should click and the cone should move a little.
Rehook it to the amp, do you hear *something* when you turn it on? Some click, low level hum or hiss? Even if you have to stick your ear to it.
I know no live amp *absolutely* silent.
Check (carefully) that you have +B and -B at the power supply (around 40V) and the ICs receive their +/- 15V diet.
If it's early technology it might be made with discrete transistors instead of ICs, they may live on a single +20 to +35V supply.
Post the codes you read on the ICs , if any, and on the output and driver transistors, also what's printed on the big electrolytic cans.
Does it have internal fuses?
Post a clean picture or two.
Good luck.

Thanks a ton for the pointers.

Cured by a new headphone jack.  If this craps out in this amp, it takes out the speaker.