Resistance Check Question [resolved]

pbvoorhees · 310

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Offline pbvoorhees

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on: January 07, 2025, 01:58:38 PM
Greetings!
I just completed the build of my first kit. I am pretty excited.
The next step is the resistance check.
All of my testing so far (generally) lines up with the numbers in the guide but I want to confirm that I am doing this correctly.
Question 1:The instructions say "Attach the negative lead to the ground buss at terminal H1'. Is the 'ground buss' the ground located directly next to the IEC inlet? Question 2 (And my real question about resistances): Terminal 15 should read 0 but I keep getting a reading of 0.1 for a moment and then it jump to 1.2. I've tested this terminal numerous times and I get this same reading consistently.
The jump to 1.2 is throwing me off and seems like something might be wrong.
Any ideas or suggestions are welcome.
Thanks.
Pieter
« Last Edit: January 08, 2025, 02:09:48 PM by Paul Birkeland »



Offline Paul Birkeland

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Reply #1 on: January 07, 2025, 02:57:07 PM
H1 is just a convenient place to grab a ground. 

15 touches the chassis and H1 touches the chassis.  If you are seeing 1.2 ohms of resistance between them, what does your meter read for resistance when you just touch the meter probes themselves together?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline pbvoorhees

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Reply #2 on: January 07, 2025, 04:13:44 PM
Thanks for the quick reply.

I re-tested using H1 as my ground and re-tested. Same results. All looks good.

But terminal 15 still reads 0.1 and then jumps to 1.2.

To answer your question: When I touch the two probes together most times, I see 0.1

I say most times because sometimes the number dances around wildly. 



Offline Paul Birkeland

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Reply #3 on: January 08, 2025, 05:41:55 AM
You could try tightening the hardware at terminal 15 and that might help a bit, but 1.2 ohms of resistance there  wouldn't be enough to prevent me from turning the amp on.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Doc B.

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Reply #4 on: January 08, 2025, 07:41:32 AM
Quote
To answer your question: When I touch the two probes together most times, I see 0.1

I say most times because sometimes the number dances around wildly. /quote]

That is because contaminants like skin oils and oxidation get on the prob tips. Try rubbing the tips against each other to polish them a bit and typically the reading will be more consistent.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline pbvoorhees

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Reply #5 on: January 08, 2025, 12:13:36 PM
A quick follow up here:
I tightened the screw on the top plate for terminal 15 and voila!
I am suddenly getting readings of 0.2
Many thanks for the suggestion. This solution would never have occurred to me.
Next up, the voltage check  . . . Fingers crossed.