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RCA WV-98c
morzh
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#31

11-10-2024, 09:22 PM
strange. It should have more even to the GND, and the GND is 1M to the case.
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daveone23
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#32

11-11-2024, 08:30 AM
Are you saying if I measure ohms from the ground lead to case it should be 1m ohms? That low resistance tells me there is a leak to ground, right?
(This post was last modified: 11-11-2024, 09:03 AM by daveone23.)
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morzh
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#33

11-11-2024, 08:47 AM
Well, in the sch you provided (there is something missing at the very bottom, but I think it is GND), the sole connection to the case shown is the 1M resistor R31, which is used to bring the case and the GND under the same potential.
Unless I am missing something.

Of course there is a cap across that R31. And it could be bad. Or, again, we are missing something.
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daveone23
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#34

11-11-2024, 09:17 AM
I guess I need to look at r31 and C7.


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morzh
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#35

11-11-2024, 09:25 AM
That too.
There might be other things.
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daveone23
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#36

11-11-2024, 04:28 PM
Interesting readings, r31 common ground to case bounced to 1meg on analog meter, r31 common to case bounced to 1meg. R31=1meg.  Across c7, which is common to case with a parallel resistor = 40k ohms steady.
(This post was last modified: 11-13-2024, 11:41 AM by daveone23.)
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daveone23
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#37

11-11-2024, 06:40 PM
My resistance readings are not even close. Worried about pins 1 and 6. Even though they are off, the meter works on dc 50v and higher.
(This post was last modified: 11-13-2024, 11:41 AM by daveone23.)
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morzh
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#38

11-11-2024, 07:20 PM
>>r31 common ground to case bounced to 1meg on analog meter, r31 common to case bounced to 1meg.

Would you re-read and correct?
This does not make sense.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
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morzh
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#39

11-11-2024, 07:21 PM
Check all your caps. Even ceramics. I am not sure what is going on.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
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morzh
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#40

11-13-2024, 10:24 PM
Just occurred to me: what if you have a power transformer leak? From a, say, secondary to the case. If it is bolted to teh case.
Not sure how to better check it.
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daveone23
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#41

11-14-2024, 09:46 AM
Thats a good thought but the secondary does go to ground via R30 27k resistor.
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morzh
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#42

11-14-2024, 10:26 AM
Yes.....it would connect GND to case, and you do have 1MOhm.....

I am not sure how the wiper has resistance to the case.
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daveone23
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#43

11-15-2024, 03:56 PM
From now on iam using an analog meter. R31 removed is 1 meg and c7 .01 but chassis to common is 600k. Why is that?
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morzh
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#44

11-15-2024, 04:22 PM
Are you saying the Chassis to GND became LESS when you removed the R31?
And we are sure the C7 and other caps are not leaking?
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daveone23
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#45

11-15-2024, 05:57 PM
Yep, hunting down the source. Will get back to you. Thanks
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