Ah, hi 1bass! Thanks for replying.

I'll give you a more detailed rundown on the sitch here.

Again the problem is that there is no output from any orifice on this thing, such that neither the pre nor power sections can be isolated as the culprit.

I've noted that this and some of the newer (and older? I dunno) Marshalls have muting circuitry as part of their Neutrik 1/4" connectors, so that if you don't have anything plugged into the input the whole system is in mute mode. I'm heavily leaning towards the possibility that it's somehow not unmuting when I plug in. The fact that there is utter silence from the speakers indicates to me that, assuming the OPTs are good, it's just a matter of finding out why the system is in mute mode permanently.

You can find the schematic for my amp at:


I've not done any live testing yet, but I am somewhat experienced working with hifi tube amps in the past and the safety issues involved. I'm a total wimp when it comes to pain and electrocution so I certainly won't be taking any chances when it comes to measuring voltages, etc. lol.

If you can maybe give some insight on how to maybe test the muting circuit and/or fix it I'd be most grateful. I'd just as soon give this unit to an official repair shop, but there ain't none for about a thousand miles, and even then the cost of shipping would make it prohibitively expensive to do.



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