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relay and diode

chrisjw24

New Member
I have a sony TA fe 374 amp .
powers up and headphones work but no speaker output.
The speaker relay does not click.
Nothing on the board looks fried.
I can get a relay from cpc but there is a small diode ( iss119 25 )in the circuit.
This reads faulty (still in circuit) is this something to do with relay coil.
Can anybody recommend an equivalent please.
 

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Even a good diode D601 clearly in parallel of a relay coil will appear bad, can be perfectly healthy with no need to guess-replacing it. It is implemented there to protect the circuit that energizes the relay.

Measure speakers output nodes for direct current before the relay, both channels, zero volume. If there is DC on any, the protection circuit will prevent the relay to connect the speakers to avoid frying them. And by the way check 'speakers-on switch' if there is one.
 
Last edited:
Ok thanks.
I took relay out it tested ok.
Diode is good with relay out.
Voltages on resistors where 0.15 and 0.09 would that be enough to cause s problem.
I will check the soldering.
Thanks.
Would I get good headphone output if the stk had failed.
 
Last edited:
Ok thanks.
I took relay out it tested ok.
Diode is good with relay out.
Voltages on resistors where 0.15 and 0.09 would that be enough to cause s problem.
I will check the soldering.
Thanks.
Would I get good headphone output if the stk had failed.

It's a bit confusing, as the headphones come off the top of the tone controls - but following links from page to page, it's actually fed from the output of the STK, before the relay.

The voltages on the output seem low enough not to trigger the protection though.

I presume you don't hear the relay click over after a few seconds?, what are the voltages on the diode D601?, the anode should be 0.8V or so if the relay is being triggered, and the cathode is fed power from 47V via two series resistors, so should be between 0.8V and 47V. If the relay isn't been triggered, they should both be about 47V.
 

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