Need help on Sony KV-8000 with troubleshooting.

[Popester]

I’ve been back at it. I replaced 6 lytic caps in the video drive. Still very very faint luminance. I thought I would test the jug and see what kind of shape it’s in and check for shorts. I pulled out the B/K 467 and that manual and the B/K 490 don’t list the socket adapter. The Sony parts number is 8-737-701-05 and the description is 230BWB22. Anyone know what the socket number I’m suppose to use is? I haven’t made a universal adapter and don’t have hardware to make one yet. Any ideas?

[zeno]

Looking at the pixs of the force on your CRT is at least
good if not better.
The color is probably OK & you are just seeing that but no video.
Take back what I said about cathode voltages. This uses less.
Keep in mind as the cathode V goes higher the pix will darken
so I bet all 3 are up to 120 VDC.
Measure the DCV along the video chain & trace with scope & see
where the video drops out or the DC voltage is off.

73 Zeno
LFOD !

[Popester]

So, checking all three R,G,B drive transistors Q701,Q702,Q703 I seem to have 4.5V video signal P-P on my scope at the base of the transistors. I'm suppose to have according to the Sony schematic 6.3V P-P. I've included pics of the schematic so I hope you can follow along. The collector of all three of these is reading source voltage which is 126Vdc. The collectors should be at around 100 Vdc. It's like the transistors are biased off. All three emitters are about 4.63Vdc and should be about 5.4Vdc. The base voltages are low too they are reading 3.05Vdc and should be 5.0Vdc. I replace the following lytics in the video circuit to no avail. C441,C442,C404,C405,C406 and C301. I've checked transistors tonight in circuit and injected video which didn't help from the B/K analyst. I didn't see video. I have very very faint color bars on the screen. It's basically color without luminance. When I'm on the color bars if I vary brightness, and picture controls I see slight changes. If I vary color and hue I notice intensity from no color to very slight color. And hue I see a shift in my bars changing phase. I wish I could just figure out what is effecting my bias turning these outputs off. I hope the pics are helpful to someone out there. Attachment 197700

[Popester]

Second image.

[zeno]

This is what I meant by challenging.
SAMS gives 12V P-P B of Q402 & 6.8V P-P on the C
Also check around Q507 & Q407
Thats about it as far as DX repairs. Its to the point of having to be there.

73 Zeno
LFOD !