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November 26, 2021, 03:49:04 PM

Author Topic: Cathode Wiring Resistance at A1 and A4 [resolved]  (Read 482 times)

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Offline Roamconstant

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Cathode Wiring Resistance at A1 and A4 [resolved]
« on: June 08, 2021, 05:47:56 PM »
I've retraced my steps and looked at all the solders.... my eyes aren't finding the flaw. 
Any ideas here?

I get a L resistance reading at A4 and 0.00 ohm resistance at @ A1.  It shows the right voltage off the Reg terminals on the filament supply board so I know everything up to that point and the tube glow test is correct.

« Last Edit: June 09, 2021, 06:48:46 AM by Paul Birkeland »

Offline Roamconstant

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Re: Cathode Wiring Resistance at A1 and A4
« Reply #1 on: June 08, 2021, 05:50:50 PM »
More images

Offline Roamconstant

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Re: Cathode Wiring Resistance at A1 and A4
« Reply #2 on: June 08, 2021, 05:58:16 PM »
Would like to post more images but it doesn't seem to be working. 

Offline Paul Birkeland

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Re: Cathode Wiring Resistance at A1 and A4
« Reply #3 on: June 08, 2021, 05:59:21 PM »
I would be sure the tubes aren't in the sockets when checking these resistances.  Is this only an issue on the A side socket?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Roamconstant

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Re: Cathode Wiring Resistance at A1 and A4
« Reply #4 on: June 08, 2021, 06:06:54 PM »
Tubes are not in the sockets. 
Yes- only an issue on the A socket thus far.  There's some more resistors to add to B socket area before the resistance gets measured there.  Just for giggles I checked the resistance at B4 and B1 (before the resistors w/ heat shrink are added) and I get 10.6 to 10.8 Mohm on that side.

Offline Paul Birkeland

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Re: Cathode Wiring Resistance at A1 and A4
« Reply #5 on: June 08, 2021, 07:15:56 PM »
Can you show me the meter you're using?  If you don't have an autoranging meter, you may get nonsensical resistance values if the meter isn't properly set.  Something else you could do is just try to measure the one loose 330 ohm resistor you have with your meter to double check.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Roamconstant

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Re: Cathode Wiring Resistance at A1 and A4
« Reply #6 on: June 09, 2021, 04:13:54 AM »
I met George Ohm in a dream last night.  This morning I measured the resistance with the circuit off.
All is well.  I’ll just add this to your tab, Paul.


Offline Roamconstant

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Re: Cathode Wiring Resistance at A1 and A4 [resolved]
« Reply #7 on: June 10, 2021, 02:00:44 PM »
Small question: the manual says I should measure close to 100VDC on terminals 6 and 16. 
I show 87VDC for both.  Close enough that I got everything right?

The voltage at 25 and 30 showed 10VDC as expected.

Thanks!

Offline Paul Birkeland

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Re: Cathode Wiring Resistance at A1 and A4 [resolved]
« Reply #8 on: June 10, 2021, 04:20:53 PM »
Yes, 87V indicates a nice healthy 300B.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man