Marshall Stanmore repair HELP please

Thread Starter

Benjimann

Joined Dec 8, 2023
4
Wondering if anyone can shine some light on repairing an amp I’ve acquired from a friend, it doesn’t turn on when power is connected, switch is fine it’s getting 240v to the connector but it doesn’t switch on there’s no power to the second board. I’ve seen this video on YouTube link below


am I right in saying if I replace that chip he shows near the end it should work? Or do I need to follow the process and check other things as I go?

any help is appreciated,

thanks
 

SamR

Joined Mar 19, 2019
5,019
Trace it through. Does the input power make it past the ON/OFF switch? Then keep going...

And Welcome to AAC!
 

Thread Starter

Benjimann

Joined Dec 8, 2023
4
Trace it through. Does the input power make it past the ON/OFF switch? Then keep going...

And Welcome to AAC!
I’m not massively clued up on what I’m testing and how to follow it if I’m honest. But I’ll give it a go lol
 

SamR

Joined Mar 19, 2019
5,019
I’m not massively clued up on what I’m testing and how to follow it if I’m honest. But I’ll give it a go lol
You are dealing with deadly voltages so you must be very careful and for safety use an isolation transformer and Variac to trace LOW input voltages! Download the schematic and manual from the net to follow. Or, take it to a repair shop if you don't know what you are doing.
 
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Thread Starter

Benjimann

Joined Dec 8, 2023
4
Ok so I replaced 2 1004 resistor and the ob22 chip, still nothing I’m not sure where to go from here but I’m measuring another 1004 and getting 0 voltage, it’s the only one untouched in the pic I’ve attached lol, any ideas? And yes I know it’s a bit rough but I’m measuring voltages over the 2 smd’s ive replaced.
 

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Thread Starter

Benjimann

Joined Dec 8, 2023
4
Ok so turns out I didn’t place the power switching module and it kind of fell off, I’ll try get that on properly and go from there, my bad
 
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