Resistance check question [resolved]

dth31 · 1894

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Offline dth31

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on: February 26, 2017, 11:33:02 AM
I bought one of the last Paramounts and am finally getting around to finishing it.  2A3 version.

The resistances check out except for the Zener string that goes to the driver tube pin B6.  The resistances I measure, in both amps, are approximately 1/4 of what they should be.

T11 measures 0.79 Mohms.  Should be 3.0 Mohms.
T12 measures 1.32 Mohms.  Should be 5.6 Mohms.
T14 measures 1.92 Mohms.  Should be 9.2 Mohms.
T15 measures 5.52 Mohms.  Should be 15 Mohms.

Is this OK?  Or a problem?  Haven't checked voltages yet.

Thanks,

Dave
« Last Edit: March 08, 2017, 12:55:22 PM by Caucasian Blackplate »



Offline Paul Birkeland

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Reply #1 on: February 27, 2017, 06:05:09 AM
That likely isn't a problem.  What you want to look for with the zener string is that all the diodes are facing in the proper direction, as putting one in backwards can create a lot of problems.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline dth31

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Reply #2 on: February 27, 2017, 07:01:15 AM
Thanks Paul!  Both Zener strings are oriented correctly.  I'll check the voltages tonight and go from there.

Dave



Offline dth31

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Reply #3 on: March 05, 2017, 11:39:42 AM
Thought I would give a quick follow up.

Voltage check went well.  Everything was within ~10% except Kreg voltages.  Kreg A was 2.8V in one amp and 3.1V in the other.  I saw in another post from PB that Kreg A needs to be at least 2.5V, and others with 2A3 version have had low values, too.  So while 2.8V is low, it's also OK.

Thanks for your help, PB!

Dave