Data East Time Machine - No displays

[WannaTheater]

Trying to get a neighbors Time Machine displays to work-  Nothing is lighting up.  The game seems to play fine.  Checked F3, which is good.  Checked input voltages to display board.  5V is OK, -100V is ok, +100V is missing.  Doesn't seem like it is making it off the power supply board.  From the schematic, there are 2 transistors in the +100V circuit (TR2 and TR4).  Since I only have the board, and nothing to test it in, I am planning on testing the diodes with meter, and just replacing the 2 transistors and associated caps. 

Any other places to look?

[busa32927]

yep it makes sense.  you need the -100v and the +100 voltage to work.  There should be a high voltage rebuild kit out there for the power supply. 

[WannaTheater]

So I tested all 4 transistors out of circuit (for both +100 and -100 lines), and they ring out OK... also tested diodes.  I'm at a loss-

(and correction from last post, it was TR1 and TR3 for the +100V line).

When I tested the voltage at the Display board connector, the harness was connected- I measured at the header pins.  Could something on the display board be pulling the +100V line down?  Should I have measured the voltage at the connector, WITHOUT it being connected to the display board?

[FUNWIZ]

Open the door, put it in test mode, find the “back in time” setting, set the date back to when it worked, hit enter, exit test mode, and the games back working fine.  If that doesn’t work, guess we’ll have to troubleshoot it the old-fashioned way…

When testing the power supply board, should always be tested under load first and if something is amiss, turn it off, disconnect the output connectors, turn the game back on and retest. If voltage is now present, then you have a short elsewhere on the game. If power is still amiss, then you need to troubleshoot that section.

+100v  Look at the voltage on C10, +, Should read over 100v. The voltage passes through TR3 which is an MJE340 transistor, which is hard to find these days. You could have a bad Zener diode which is at D6, 1N5228, which is the same as D8, in case you want to swap them around to see if the voltage comes back.  Zeners D9 and D10 1N4764 are also the same and can be swapped around if needed for testing.
GL

[WannaTheater]

Can anyone provide where to purchase the big monster silver cap (C4) 0.18F 25V.
Its about 3 inches long.  There doesn't seem to be an issue with the circuit it is in, but the top seems a bit puffed (its actually a bit squishy on the top- its not a metal top)

Thanks-

[atarijim]

Those power supplies are notorious for having bad caps that leak above the HV supply and arcing, causing the trace to burn
apart. My fix is to dremel out the trace and jumper on the back, replace the caps and any other failed parts.
I also don't replace the axial cap, but sub out a snap in and also run jumpers, It may not be the prettiest fix,
but you can't always fix a bad design without some acne. See below:

UofF - keeping ugly girls out of the UofM for decades...........

for ibis!

aj

[WannaTheater]

Those power supplies are notorious for having bad caps that leak above the HV supply and arcing, causing the trace to burn
apart. My fix is to dremel out the trace and jumper on the back, replace the caps and any other failed parts.
I also don't replace the axial cap, but sub out a snap in and also run jumpers, It may not be the prettiest fix,
but you can't always fix a bad design without some acne. See below:

UofF - keeping ugly girls out of the UofM for decades...........

for ibis!

aj

Thx.  Did you mean to supply a link?