[sdiy] TX802 Power Supply repair techniques

dragons dragon.servicing at googlemail.com
Thu Mar 13 21:29:02 CET 2014

I just wanted to check what load you are trying out the power supply 
with ? ( hopefully NOT the Tx802 ! ).
I think that normally you do need a load across the outputs for the 
supply to start up correctly. From the link you posted I think you would 
need at least a load across the 5 volt supply to have a chance of the 
power supply starting up.
Fault finding SMPS isn't easy ( well at least I have never found it so ! )
It would be worth checking resistor values ( you may have to unsolder 
one end of them to be sure of the value ). If the resistors R3 and R4 
have drifted up in value it may start erratically.
I think that the electrolytic caps may have aged as well ?

regards Peter B

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