Dmd driver bd query

[paddythegreek]

Went to look at a mates RS which had a dead DMD. No 62v. Brought the board home and replaced Q3 and all the associated components. Test board in my FT. All outputs voltages are correct inc the 62v and I have 12v difference between the two HV’s (113v - 125v).
When I plug in the DMD I have only 1/2v instead of 62v. It’s as if the dmd is dragging it down. I’ve tried another working dmd and it’s the same. No 62v. Put my driver board back in FT and all good. Any ideas please. Ken

 

[Pick Holder]

Do a full rebuild of the HV - had so many weird faults on these boards. Truthfully - I just put in a new board these days.

 

[Asiapinball]

Had similar issue with 5v on a baywatch. 5v OK with no load but plug in a known working dmd the 5v dropped to 0.5v. Fault was the main tr5 transistor with the big heat sink on the 5v supply on the power board. Dont have wiring diagrams in front of me for rs but is there equivalent transistor on the 62v

 

[paddythegreek]

Update. If I remove both J601 & 602 input ribbon cables with the display connected I’ve got 62v. Plug either one in and just over 1/2v again.
Pick, I’ll rebuild all the H/V section first then try it. Thanks guys.