G07 Issues - Still

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I've been working on a G07 for a few days now. No picture or neck glow. Replaced HOT and X401, did a cap kit. Fuses checked out ok, still getting nothing. I checked the flyback for cracks (looks like it may have been replaced once already) and it looks intact. My question is: Can a flyback go bad without the telltale cracks/leakage?
 
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I've been working on a G07 for a few days now. No picture or neck glow. Replaced HOT and X401, did a cap kit. Fuses checked out ok, still getting nothing. I checked the flyback for cracks (looks like it may have been replaced once already) and it looks intact. My question is: Can a flyback go bad without the telltale cracks/leakage?

It absolutely can.

Did you pull the fuses out to test them? Checking while still installed can be inconclusive.

Have you measured the B+ voltage? Knowing that will help us to get this thing going.
 
When I took a closer look, f901 was actually 2.5A and not a slo-blo. Replaced it with the correct fuse. Plugged it in and instantly blew f902. Flyback then, right?
 
When I took a closer look, f901 was actually 2.5A and not a slo-blo. Replaced it with the correct fuse. Plugged it in and instantly blew f902. Flyback then, right?

It needs to bea fast-acting fuse, NOT a slo-blo.

Set your meter to diode, put the black lead on the outside case of the HOT, and alternate the red lead between the 2 legs of the HOT. If you get a reading like .479 (or anything like that), the hot is likely still good, and then yes the flyback is probably toast.

That b+ big grey filter cap is holding a charge, don't touch it!

Short the 2 legs of that cap together with a screwdriver .
 
Have you used the flowchart for the GO7 that I sent the link for? If F902 blew it is pointing towards these diodes D901-D904 or the degaussing coil.

Also are you using an isolation transformer to power the chassis?

Ed
 
i actually brought it home and tested it in a spare cab with a switching supply, but the cab it goes in has the original PS. I did look at the flowchart and will be checking those areas. Also, measured .197 on both leads on the HOT when it's in place. When I remove it, I get .50. Diodes all read good (yes, I removed them when I checked).
 
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Using the flowchart would have helped with the hot. It tells you how to check it in circuit. Been doing this for 30 plus years and every time I have checked one that way it hasn't been wrong.
 
I do appreciate the help with the flowchart, thanks. Going back to that: initially, f901 was blown. This would suggest that the HOT was bad, or the flyback. The hot tests good now (swapped multimeters, kept the original one and tried it in circuit, it's at .50). So it would be the flyback then (surprise!). I'll post results once I get it in.
 
You said initially F901 was blown. You replaced it with a correct fuse and swapped the HOT. Then F902 blew. Is F901 and your HOT still good? If yes your FBT may be OK. continue down the chart troubleshooting a blown F902.
 
Replaced f902 and unplugged the degaussing coil. Plugged it back in and this time f902 held, but f901 blew. Checked the HOT and it's still reading good (.501-ish). From the chart = bad flyback. I guess I go from there and see. Thanks again for the help!
 
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Hmmmm.... Replaced the flyback, still blowing f901. X01 measures around .50. I say "around" because I'm noticing that it starts at around .35-ish and gradually increases as I continue to hold the leads to the transistor. When I remove the leads for awhile, it resets to a lower level and increases back up to .5 again. Should I be looking for a short involving a capacitor at this point?
 
I have at least a few of these maybe 4 or 5 with all new stuff that lasted a little while then nothing. I think the new flybacks are likely shit. Maybe it's something else, all I know is I hate them.
 
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