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May 08, 2021, 07:10:51 AM

Author Topic: Resistance testing problem  (Read 180 times)

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Offline Freddyhoule

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Resistance testing problem
« on: April 25, 2021, 05:47:10 AM »
So far so good but, but I have the same problem with resistance  on terminal 3, 8, 13, 18. While they are supposed to read 22 ohms, they all read 0.1 ohm. Did I miss something?

Online Paul Birkeland

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Re: Resistance testing problem
« Reply #1 on: April 25, 2021, 06:58:38 AM »
Where is your black meter probe connected?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Freddyhoule

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Re: Resistance testing problem
« Reply #2 on: April 25, 2021, 12:39:00 PM »
To terminal 23. Same reading (o.1 instead of 22) with terminal 22, 25, 32 and 35

Online Paul Birkeland

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Re: Resistance testing problem
« Reply #3 on: April 25, 2021, 01:24:39 PM »
Terminal 23 connects to 32 through a 22 ohm resistor with the diodes and cap across it.  32 connects to the chassis and the rest of the terminals.  If you have nothing plugged into the preamp you should get 22 ohm between 23 and the chassis plate, but it may be somewhat meter dependent since the diodes are there.

If you temporarily disconnect the resistor/cap/diodes bundle at terminal 32, what DC resistance do you get between 23 and 3?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Freddyhoule

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Re: Resistance testing problem
« Reply #4 on: May 02, 2021, 07:45:48 AM »
0 volt

Offline Doc B.

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Re: Resistance testing problem
« Reply #5 on: May 02, 2021, 10:04:08 AM »
0 volts is not a resistance reading. PB is asking you to measure the resistance in ohms, with the amp off.
Dan "Doc B." Schmalle
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Offline Freddyhoule

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Re: Resistance testing problem
« Reply #6 on: May 02, 2021, 02:21:27 PM »
0.1 ohm

Online Paul Birkeland

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Re: Resistance testing problem
« Reply #7 on: May 02, 2021, 03:02:40 PM »
Can you post some build photos?  There shouldn't be any connection between those terminals except through the 22R/UF4007/0.1uF components that you've removed.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man