18-07-2019, 03:15 PM
There is an anomaly on this pcb.
C5 is not fitted, looks like it never was.
The circuit shows it in the -5v regulator feed. In fact it is between pin6 of the TL331 and ground.
Testing it today and I have another catastrophic failure back to where i started. No regulation at all on the +5v, its at 25v and the TIC31 and the UA723 are duff. What state the obsolete TL331 is in I have no way of establishing.
I think that's it for this board, it obviously is beyond my ability to understand it or fix it. Patience with the 36 year old horror is over, I'll gut some space on board to piggy back a buck module on.
Unless anyone has any bright ideas.
Bugger, I hate being beaten.
C5 is not fitted, looks like it never was.
The circuit shows it in the -5v regulator feed. In fact it is between pin6 of the TL331 and ground.
Testing it today and I have another catastrophic failure back to where i started. No regulation at all on the +5v, its at 25v and the TIC31 and the UA723 are duff. What state the obsolete TL331 is in I have no way of establishing.
I think that's it for this board, it obviously is beyond my ability to understand it or fix it. Patience with the 36 year old horror is over, I'll gut some space on board to piggy back a buck module on.
Unless anyone has any bright ideas.
Bugger, I hate being beaten.
Boater Sam.
