> capacitance - but high or very high  ESR.
>
> Richard P

have sit-down for 2 days pushing PCB here & there, no luck, nothing 
improved, is good ideal to chk the cap. but what is "ESR"= ???

what is the nominal voltage between cat. to G1 ?   RGB cathode =60VDC, 
G1=-180VDC, 60-180= -120VDC, cathode grid bias at -120 to high, I think it 
might cause too dark in picture. or ABL (auto brightness limit) activated. 
pump-up HV switching transistor 2SC5914, it seem like missing diode at C_E, 
but no luck to find datasheet at "alldatasheet.com". maybe no diode inside 
C_E on purpose from manufacture.

darkness could be insufficient HV ; G2 , or ABL shutdown. somewhere there.

cllow2020

 

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