Polarity Issue During Low Voltage Circuit Testing:

[jminassin]

Moreplay Upgrade Polarity Issue During Low Voltage Circuit Test: I have 6.3 VDC on each of the tube sockets, but polarity is positive on both sockets. DMM is always connected red to red and black to black. The black and red wires reverse position at each of the two sockets. Red wire goes to plus at the pcb; black wire goes to negative for both sockets. Why don't I have negative voltage on one of the tube sockets?

John

 

[jminassin]

Moreplay Upgrade High Voltage Test: 6U/16U within spec. B+ Reg TP slightly high at
184.5 VDC. Mains voltage is 118.5 VAC.

Let me know if this is ok, and I will install the pots.

Thanks,

John

 

[Paul Birkeland]

I have 6.3 VDC on each of the tube sockets, but polarity is positive on both sockets. DMM is always connected red to red and black to black. The black and red wires reverse position at each of the two sockets. Red wire goes to plus at the pcb; black wire goes to negative for both sockets. Why don't I have negative voltage on one of the tube sockets?

I think you'd have to let us know how what you're measuring differs from what's written in the manual. I'll quote from the test there:

Repeat the same test for the B socket low voltage power supply, bearing in mind that the polarity is reversed between the sockets, so you may see -6.3V on the second socket if your clip lead orientation is maintained.

 

[jminassin]

I think you'd have to let us know how what you're measuring differs from what's written in the manual. I'll quote from the test there:

Repeat the same test for the B socket low voltage power supply, bearing in mind that the polarity is reversed between the sockets, so you may see -6.3V on the second socket if your clip lead orientation is maintained.

Hi Paul,

If my DMM clip lead orientation is maintained (red to red and black to black on both tube sockets) shouldn't I see plus + 6.3 VDC on one socket and -6.3 VDC on the other? I see +6.3 VDC on both sockets.

 

[jminassin]

Also, I am at 184.5 VDC at B+ Reg TP where the spec is 175-180. Mains voltage was 118.5 VAC at the time of the measurement.

Should I be concerned about this? I see that someone else had a similar reading and PB did not think it would be an issue.

Based on this I'm going to install the pots tomorrow.

Thanks,

jm