G07 High B+

GoneMad

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G07 Low B+ now

I come across a dead G07. Thought I would try bring it back to life. I now have a B+ of 159V that I can't adjust. Here's what's new
Cap kit
New flyback, HOT, and Volatage reg.
Replaced both fuses.
Replaced filter cap
Replaced X901, X902, and X701
Replaced R908

B+ sits at 160V, no neck glow. Bad B+ pot maybe? Something I don't have new of either.
 
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Yeah probably wouldn't hurt to replace the B+ pot. Bob Roberts has them.

If anything, it rules out another factor on your issue list.
 
I encountered this last year on one of my games and had a non-adjustable b+ of about 160 putting it into shutdown mode. After much searching, turns out the HOT that was replaced was not installed properly and the insulation piece was not effectively isolating the HOT from the chassis. Something worth checking.

Good luck!
 
Yeah probably wouldn't hurt to replace the B+ pot. Bob Roberts has them.
If anything, it rules out another factor on your issue list.

Yeah, if dialing this pot up or down does nothing to your B+ voltage, I would put it on the suspect list.....
I have found quite a few bad, so they are def a fail item.....
 
Look for cracked traces around flyback if you were forceful installing new flyback. check solder joints on T501.

Andrew
 
I reflowed a lot around the flyback area and checked for broken traces and found none. I replaced IC501 and booted up again. Heard power getting to the crt and had an orange screen. Checked B+ was at 99V but could not adjust up any. Pot must be bad. I'm assuming the orangish screen is because of the low B+. I know the pot is a 2K pot but is there a certain kind that it has to be, or a regular 2K pot work?
 
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With DMM in diode mode, should this be passing current both directions? It is from D506. I haven't pulled D905 out of circuit yet, but it seems to be doing the same. Both passing current in either direction. 506 is doing it out of circuit.
IMG337.jpg
 
I also noticed that R908 is only measuring around 44k, should be 47k. Then I checked the rest of the resistors in the pack Bob sent me, and they all measure at 44k. Does this matter or could this combination of out of spec/faulty components lead to low/unadjustable B+?
 
That 3k is within the 10% tolerance. I doubt that it's your issue. If it were open, I would say that that was your issue.
 
Well, after going over this and replacing three bad diodes, I now have the B+ sitting at a perfect 120V. Only to be faced with this screen. I'm not even sure where to start to trouble shoot this.
IMG350.jpg
 
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