RCA WV-98c - Printable Version
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RE: RCA WV-98c - morzh - 11-09-2024
Two things.
1. Make sure your switch is clean and provide good contact across all ranges. It is S2 Range switch.
2. I don't think this is it (I think only the lower dual triode is involved for DC, as for everything else), but just in case, have the tubes been checked?
RE: RCA WV-98c - daveone23 - 11-09-2024
Tubes and resistors are fine. R22 measures 9k so iam not sure if that could be the issue.
RE: RCA WV-98c - morzh - 11-09-2024
Switch. Check the switch. Make sure it makes good contacts. Clean if necessary, Deoxit D or any contact cleaner (be careful and don't spray it all around).
RE: RCA WV-98c - daveone23 - 11-09-2024
I cleaned and checked the sw2 switch, its fine. Has to be something in the .5v to 15v circuit. Iam going to check the ac operation.
RE: RCA WV-98c - daveone23 - 11-09-2024
No ac function. Pegs the meter to the left, no adjustment.
RE: RCA WV-98c - morzh - 11-09-2024
If I had it in front of me, I would triy to trace the signal on one of the non-working functions.
Try to trace and highlite at least one non-working path.
RE: RCA WV-98c - daveone23 - 11-10-2024
At this point, there is no input, just internal voltages
Which are incorrect and not sure what they should be.
RE: RCA WV-98c - morzh - 11-10-2024
Those will probably depend on teh switch combination.
Could you list some that you see, their values and what they should be (if you know correct values)?
RE: RCA WV-98c - daveone23 - 11-10-2024
Check out this crazy zero pot operation. Touching it drives it crazy. Its rubber tipped. Also the 6al5 has no negative voltage on it.
https://www.dropbox.com/scl/fi/gnvltn9lapcdtb6clcxs6/20241110_114216.mp4?rlkey=s5m56hbrv0j2wpb0scr9vsi6b&st=iqafvikk&dl=0
RE: RCA WV-98c - morzh - 11-10-2024
If this is R22, check the voltage on the wiper (86V).
If this is R33, see if the lower pin indeed connected to GND, the wiper is indeed wipes, and if the pot is OK.
RE: RCA WV-98c - daveone23 - 11-10-2024
I measured the wiper of r22 , 95vdc.
RE: RCA WV-98c - morzh - 11-10-2024
The resistor you are touching at the video, is it R22 or R33?
RE: RCA WV-98c - daveone23 - 11-10-2024
R22, but it doesnt do that all the time. Strange. What do you think of the 95 voltage. I guess its close.
RE: RCA WV-98c - morzh - 11-10-2024
Yes, it is close. It is a solid state diode rectifier, so the voltage won't depend much on the load, as would with tube rectifier.
However the behavior is strange.
Also, see if this pot,s case (and so the shaft) should be grounded through the fron panel, and somehow it is not.
RE: RCA WV-98c - daveone23 - 11-10-2024
Case and shaft go to case. Center wiper of r22 has 3kohms to case.