Marshall 5210 lunching a resistor

[primofacprima]

Give me a clue mate, can't find a 33v zener...

[g1]

  I think he was looking at the schematic from the Randall thread, I don't see a 33V zener here.

[Roly]

{sorry for the brainfart  }


No CRO?  The you are going to need a signal tracer of some sort.  Can you dredge up an old pair of powered computer speakers from somewhere, only one working channel is needed; any amp+speaker can be pressed into service, even tape deck and headphones, etc.  A ground clip and a probe with a small DC isolation cap and series resistor to protect the tracing amp input.

Feed in a signal from some tape/CD/MP3 player and trace along the signal path until you locate the break.

IC2b pin 5?  Input signal?
IC2b pin 7?  Output?
"Boost gain" control effective?

IC2a pin 3 - input?
IC2a pin 1 - output?

Expect the tonestack to drop the level -20dB.
Signal at top of master volume?
At wiper (off zero)?

We follow signal forwards and silence back.