Topward 6303D power supply repair

[anton74]

Hello,
I am trying to repair a Topward 6303D power supply.  The SLAVE channel works only in parallel mode with the MASTER channel; in individual mode the SLAVE channel does not respond to its voltage setting potentiometer.  I believe the fault is somewhere in the commutation circuit.  I tried to understand the commutation between the channels; unfortunately, it looks quite complicated.  Attached is the circuit diagram of the unit.  Maybe somebody could explain me the commutation of this device and/or give some directions.  Thanks.

[seronday]

I sympathise with you trying to follow the circuit diagram as it is drawn.
The way it is laid out makes it very difficult to see how the control circuit operates.

Some months ago I carried out some repairs to a Topward 6603D power supply, (The 60 volt 3Amp version), which is identical to the 6303D except for the transformer secondary voltage and additional series pass regulation transistors.

I ended up re-drawing some parts of the circuit diagram so that it was easier for me to see how the control circuit operates.

It may take a few days, but I can try to find my notes and hand re-drawn circuits to copy for you if that may help.

Regards.