G07 CBO - third of the screen is acting weird. See video.

YeastLord

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This chassis came in a large box of dead hardware. It has a new fly, caps and a few of the usual replacement parts. I turn it on and it does this. See pic and video.
Any ideas where to start? I went over this before doing repairs and it looked good to my meter. G07 Video
 

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It may have multiple issues. Looks like a bad cap, though I've seen similar odd behavior when a trace didn't have the continuity it was supposed to. The weirdest one was a similar screen
when one of the 4 lugs where the yoke connects didn't have continuity to a perfect looking trace 3 mm away. Soldered in a cap leg to connect it and it was good as new.

Pics of the top and bottom of the pcb when you get a moment please?

What is the B+. Start there.
 
Top and bottom shots. B+ @ 124VDC and the pot doesn't adjust it at all.
 

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That's a good looking board, 124 probably isn't likely the problem here, aside from the fact that you do need to address that at some point. I'd be measuring all of the large resistors near the filter cap, in circuit is fine. I doubt they go bad often, but I always change the filter cap to take that out as a possibility.
 
Have you tested this chassis on another tube, or another chassis on this tube. I always make assumptions that the tube is good. But that looks like the yoke could be in the wrong position.
 
I tested the tube with multiple known good chassis and it's solid. I have a new filter cap - I can swap it out and see if that helps.
 
I'd have to have it in front of me and probably a perfectly working chassis next to it, so I could test parts in circuit for comparison. I'd always change the filter cap even though it isn't bad very often. I'd check all of the big resistors near the filter cap. I'd test x901/x902, and I'd test the Voltage regulator in circuit. Set your meter to diode test, red lead on the leg with the RED wire, and alternate the black lead between the other post and the case. If it's a normal reading .450 ish , good, if it's .120-.250 my experience tells me the VR is failing but hasn't failed completely.
 
Filter cap tests good out of circuit. X components test good in circuit as does VR. I have a new VR that I might swap in to rule it out.
 
Yeah looks like a fun one. Maybe go through and wiggle each cap that you installed while looking at the traces to see if any of them have poor connection/lifted trace.
 
Filter cap tests good out of circuit. X components test good in circuit as does VR. I have a new VR that I might swap in to rule it out.
you have 124V B+. the filter cap is obviously good. when it's like 75V, then it's probably bad.

are people testing filter caps for capacitance and arriving at them being "bad" because they're like 30 uf under what they're rated at? because new filter caps do the same thing.
 
you have 124V B+. the filter cap is obviously good. when it's like 75V, then it's probably bad.

are people testing filter caps for capacitance and arriving at them being "bad" because they're like 30 uf under what they're rated at? because new filter caps do the same thing.
I've never seen anyone indicate that.

Most of the new ones are lower than 680uf. I don't think out of the 100 or so that I've measured (new), I've ever seen one as high as 680 uf. They are quite often right around 600uf.
 
I've never seen anyone indicate that.

Most of the new ones are lower than 680uf. I don't think out of the 100 or so that I've measured (new), I've ever seen one as high as 680 uf. They are quite often right around 600uf.
When I pulled it, it was 620 out of circuit.
 
I've never seen anyone indicate that.

Most of the new ones are lower than 680uf. I don't think out of the 100 or so that I've measured (new), I've ever seen one as high as 680 uf. They are quite often right around 600uf.
I'm just saying because security tells you to, everyone has to replace filter caps now? if your filter cap was bad you would know. I guess it's required to "rebuild" monitors "properly" and gloss over all the other things you need to do to make it right.
 
Did you cap it or did it come to you capped? Did you use a kit? If yes, you may have a wrong cap somewhere since the footprint of C408 is not a 50V cap.

Your problem looks cap related so go over the value and orientation of all of your caps again just to be sure.

Is R908 the correct value? I see it has been replaced but I can't make out the color of the bands.
 
I capped it. I'll take a look and make sure I didn't screw it up. It's possible.
I'm just saying because security tells you to, everyone has to replace filter caps now? if your filter cap was bad you would know. I guess it's required to "rebuild" monitors "properly" and gloss over all the other things you need to do to make it right.
I've done maybe 50 or 60 G07 CBOs and I've only replaced the filter cap maybe twice? I usually give it a look with the meter but in my limited experience it hasn't been a major fail point for these chassis. I'm a novice at best so you might have a different experience.
I did swap it out with a new one last night just to be sure and it made zero difference - which is a good data point.
 
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