resistance check help

bgf · 1913

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Offline bgf

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on: February 24, 2014, 12:05:58 PM
everything was going smoothly till i checked A1 to B4.  this is what i tested with 300B tube in place.

A1 5.4 ohm
A2 3.14 m ohm
A3 45.7 k ohm
A4 4.2 ohm

B1 4.2 ohm
B2 3.14 m ohm
B3 43.1 ohm
B4 5.4 ohm

volume knob was at the same setting, checked solder joints looked good, thought i would give you all a brain teaser before i started going over the wiring frame by frame.

brent fauss


Offline Paul Birkeland

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Reply #1 on: February 24, 2014, 05:07:25 PM
Your resistance readings are correct, we made a minor adjustment to the 4 pin tube socket pinouts in the manual (my error actually), and the resistances didn't get rearranged.

Thanks for checking in, you're all set for voltage checks!

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Chris65

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Reply #2 on: February 24, 2014, 05:18:32 PM
Paul, could you just clarify what the correct values are please.
Do A/B2 and A/B3 just need to be transposed?

I notice Brent has 43ohm on B3, guess that should be Kohm?



Offline Paul Birkeland

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Reply #3 on: February 24, 2014, 05:36:35 PM
What you want is ~4 Ohms on either A/B1 or A/B4, then something slightly higher than that on the companion pin. 

A2/B2 will be whacky, and shouldn't be zero.

A3/B3 will be 0-50K, depending on the volume control position.


Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Chris65

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Reply #4 on: February 24, 2014, 07:09:29 PM
Ok, thanks for clarifying that.