High voltage test [Resolved]

Suger · 1583

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Offline Suger

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on: February 07, 2022, 02:54:22 AM
Good morning. Me again.

So I'm at the high voltage test part. And the least I can say is that it's awfully scary. Because as soon as I touch the red probe to 32U, there is a big spark. I know I should use clip-on probe tips, but I haven't managed to source one yet. So I goofed up somewhere, but I don't really know where. I guess the next step is to send pictures, but as the board is getting  pretty crowded, I don't know where to start...

P.S.: the thing is nonetheless charging, a few minutes later I got a 50V reading. I'm wondering if the problem isn't that my multimeter isn't coping with the 450V....
« Last Edit: February 07, 2022, 06:41:46 PM by Suger »


Offline Paul Birkeland

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Reply #1 on: February 07, 2022, 04:09:35 AM
How do you have your meter set?  If it's set to measure resistance rather than voltage, you'll get a big spark when you try to measure the voltage.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Suger

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Reply #2 on: February 07, 2022, 04:24:56 AM
It is set to measure voltage (see attached picture, with an image of how the probes are plugged, as I guess this would be the next question ;) ). But it has a max of 500V, and if I'm supposed to get 450V±10%, that's pretty close to the limit, especially with a cheap multimeter, no?


Offline Paul Birkeland

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Reply #3 on: February 07, 2022, 04:41:30 AM
That's set to AC and you are trying to measure DC.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Suger

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Reply #4 on: February 07, 2022, 04:48:43 AM
Oops....

Alas, I still gett a huge spark when set on DC


Offline Thermioniclife

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Reply #5 on: February 07, 2022, 04:55:29 AM
If the cap installed to 32u is not soldered properly when you press your probe to that terminal it make a connection and spark. Redo that solder joint.

Lee R.

Offline Paul Birkeland

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Reply #6 on: February 07, 2022, 04:56:33 AM
More build photos are a good idea.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Doc B.

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Reply #7 on: February 07, 2022, 05:28:37 AM
Also be sure that you are only touching the terminal you mean to measure with the probe tip. If you touch another terminal at the same time you can short the two terminals together, create a spark and potentially blow components.

Dan "Doc B." Schmalle
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Bottlehead Corp.

Offline Suger

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Reply #8 on: February 07, 2022, 06:41:26 PM
OK. Thanks. I did what you said, checked the solders.

I now read 502V, so I guess the test is passed. Thanks again.

@Doc B.: that's an excellent point. I really need to find some clip-on probe tips.


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