Hi
The 3x -2.45kV wires going to the CRT are not part of the PDA high voltage supply they are the CRT heater supply and cathode supply.
Be careful there were more than one design of power supplies fitted to the 8563E.
G Edmonds
On Friday 12 July 2024 at 02:23:13 BST, saevar <saevartj@...> wrote:
Hi all
Among my recent purchases, I recently got a 8563E which I believed was functioning. It powered on when I first got it and all good except several of the buttons didn't work. I cleaned those and I thought it was a good idea to recap the power supply as you do. Long story short, the +5V and +15V seemed to be severely loaded and didn't come up correctly and I had to place the old electrolytics back on those rails to fix the problem with the rails (new caps with too low ESR?)
My new problem that I may have created for myself (maybe it was like this from the beginning, I'm not sure) is that when the 8563E has been turned off for a while (20min+ or so) it turns on correctly, but if I turn it off and on again either after a few seconds or even few minutes, nothing appears on the CRT. The +5, +15, -15V rails measures correctly. The 110V on the CRT supply is only at 34V.
I don't have much experience when it comes to CRT power supplies so I would appreciate any advise. My guess at the moment is a faulty high voltage multiplier/transformer or A17 display driver board shown below since when I disconnect the 3x -2.45kV wires going to the CRT driver, the 110V come back up (but CRT still off) but I don't know which.
Regards
Saevar
