I did replace 1D20 as it tested very different from a new ZDP one.
the uP supply is 5.12 VDC at P6-1 which would allow a tolerance of 2.5% for the regulator.
still, no StBy dot present. I “reinforced” the pressure of the two flat connectors that plug into the P6 connector to make sure there is proper contact.
i am sure some of you have been at a dead-end and that is where I am at the moment.
no issues found yet with missing continuity, the DC voltage after the rectifier looks normal and yet no StBy dot, meaning no turn-on possible.
yes, I had very briefly the StBy dot and the -/+15 supply but something must have died? Lets hope it is not the uP.
Without turning on the BG I won’t get any reference voltages (except the 5V line) which may point to other problems ?!
it might be best to shelf the BG again to “free my mind” and start again some other time.
thank you all who have been on board with pointers and suggestions, very much appreciated.
ALF
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