xm701 White Screen

pinbotler

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Hello all. Just picked up my third restore project; an Atari Football in decent condition with an nice 23 inch B&W motorola. Powered it up and the fun begins.Monitor powers up with a white screen with pcb attached or not.

Whats right:

Game plays blind and good steady picture when run via RCA to TV
Big Blue has been replaced and good steady voltage.
Checked and adjusted all monitor voltages. 30, 73,150, and 550 all test decent.
Contrast and brightness affect overall white of display, but not to a point where you can see the game.

Whats Wrong:

Did some testing and most of the SCRs and diodes test ok. Have not tried to test resistor values as yet but none seem to be totally blown or shorted.
Found a few suspect diodes. Q8 and D7 to be precise.
Q8 is listed as 48S137093 and one side tests low (230) both ways on the diode test. Probably flakey
D7 is listed as 48s134917 and tests open both ways on the emitter. both of these were tested on board but tested a couple of pinballs and a G07 this way and seems ok on the diode checks. Feel free to correct me.

Now Q8 I have crossed to a 2N3500, which I cannot seem to source locally, any other suggestions? D7 I have crossed to be replaced by two (2) 1n914s. Now this has thrown me for a loop. Does anyone have a diagram/instructions for replacing a CBE diode with two single diodes? and orientation of same? Has me stumped.

Lastly I could be barking up the wrong tree but no experience with black and white monitors in general so any help/suggestions would be great. Thanks in advance and tester at the ready.
 
Cap Kits

Thanks for the reply. Yup cap kit is on order with Mr. Roberts as we speak. Already recapped a G07 so have some experience under my belt.
 
Motorola xm 701 - solved

Just a note in the repair logs. Traced the problem down to C6. If this cap is wonky whole screen blanks a nice bright white. Now the rest of the cap Kit and on to restore my Atari Football.
 
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