RCA WV-98c - Printable Version
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+--- Thread: RCA WV-98c (/showthread.php?tid=25358)
RE: RCA WV-98c - morzh - 11-10-2024
strange. It should have more even to the GND, and the GND is 1M to the case.
RE: RCA WV-98c - daveone23 - 11-11-2024
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?
RE: RCA WV-98c - morzh - 11-11-2024
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.
RE: RCA WV-98c - daveone23 - 11-11-2024
I guess I need to look at r31 and C7.
RE: RCA WV-98c - morzh - 11-11-2024
That too.
There might be other things.
RE: RCA WV-98c - daveone23 - 11-11-2024
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.
RE: RCA WV-98c - daveone23 - 11-11-2024
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.
RE: RCA WV-98c - morzh - 11-11-2024
>>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.
RE: RCA WV-98c - morzh - 11-11-2024
Check all your caps. Even ceramics. I am not sure what is going on.
RE: RCA WV-98c - morzh - 11-13-2024
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.
RE: RCA WV-98c - daveone23 - 11-14-2024
Thats a good thought but the secondary does go to ground via R30 27k resistor.
RE: RCA WV-98c - morzh - 11-14-2024
Yes.....it would connect GND to case, and you do have 1MOhm.....
I am not sure how the wiper has resistance to the case.
RE: RCA WV-98c - daveone23 - 11-15-2024
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?
RE: RCA WV-98c - morzh - 11-15-2024
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?
RE: RCA WV-98c - daveone23 - 11-15-2024
Yep, hunting down the source. Will get back to you. Thanks