Matsushita 14" monitor B+ issue

P-man

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hi all..

I have a strange issue on a Matsushita 14" color monitor, as used in some atari cabaret and cocktail cabinets. The associated Atari manual is TM-153.

Specifically i can't get the B+ to where it should be at 115v, Q801 tests good. There is a diode marked CR806 on the schems, D806 on the pcb, but described as a Zener diode in the parts list.. the device itself says 'RM25' on it. I cannot find any reference to it, ie what Zener value it actually is..

I've removed F2, and pulled the emitter of Q802 (and tied it to another 12v source) and still get 168v.

I was thinking this diode is important in controlling the base of Q801?

anyone have any ideas?
 
hi all..

I have a strange issue on a Matsushita 14" color monitor, as used in some atari cabaret and cocktail cabinets. The associated Atari manual is TM-153.

Specifically i can't get the B+ to where it should be at 115v, Q801 tests good. There is a diode marked CR806 on the schems, D806 on the pcb, but described as a Zener diode in the parts list.. the device itself says 'RM25' on it. I cannot find any reference to it, ie what Zener value it actually is..

I've removed F2, and pulled the emitter of Q802 (and tied it to another 12v source) and still get 168v.

I was thinking this diode is important in controlling the base of Q801?

anyone have any ideas?

I don't know much about matsushita but I know IanKellogg does. I'd ask him as most people just junk those monitors when they die.
 
Is this a 100V monitor?

according to the TM-153 manual it is a 100v monitor...

Oh, and i think i managed to work out what was going on with this monitor. It is shutting down and there is zero load for the B+ supply. I have a working monitor that i compared against and isolated the B+ supply and it shoots up to 170V too, so i think this was a red herring, there's another issue now.
 
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