Thanks for the reply. I have attached the schematic and block diagrams for the outputs. Would C69 & C70 affect the output the transistors? I also measured the output of D20 and they were 20.7 and -20.9 and seems to be ok as well.
Thank you very much for your cooperation.
Now I apologise if I'm unable to continue to help
as my internet connection is about to end.
That said I think others will help as the schematics are available for anyone interested to see.
The first place to look is the block diagram as it gives an overall organisation of the AV amp system.
Refering to your 1st. post the error message is " PS1 PRT 84H"( norm 43 - 66).I don't know what it means unless I have the service manual at hand which I don't.But you zoomed in to Q20 which is in "Power3 or PS3" ( My interpretation).Which your measurements indicate all is normal as in schematic.BTW it supplies power to DSP pcb.
Anyway still the
block diagram is where the clues are.Looking at block diagram of PS1( power supply1) it supply 3 signal inputs to main processor namely:
Look at input arrow to main processor IC402.Also the output signals.
DEST-???
PDET - Power detect
/RSET - Reset?
I traced these 3 signals to "Power4" in 1st.schematic( schm.pdf). It's an auxilary transformer that supplies startup power and power to relay "RLY1"where it goes to S10 on connector W1 to PCB-FUNCTION(1).DEST,PDET and /RES are also there.
I think the problem is likely to be here.Since this is power supply. I would check and measure voltages:
1. Q6 power fet.
2. optoisolators IC1,IC2 and associated circuit.
3. Relay RLY1 and Q2
4. IC3 TC4013 logic ( but not likely).
5. Check voltages at W! connecor.
Troubleshooting should be systemstic,Power4 supplies signals that main processor will detect first before continuing with other functions/processes.
All the best.
Edit: Just realised that "Power4" is not indicated at the block diagram of S1 which I think is an oversight so newbies might have a hard time if they don't trace the 3 signals that S1 inputs to main processor.