1 LED not lighting on speedball board after probable short (but voltages fine)

billyshears · 1614

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Offline billyshears

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on: March 22, 2020, 07:10:16 PM

Hi all.

I was doing a voltage check on the small circuit board and i assume i (clumsily) touched the 237Ω 1⁄8W resistor (in R1A) cause I got a spark when I went to test 1A.  Turned it off just to make sure everything looked okay.  The fuse was fine.  Plugged it back in and got the following voltages

0A: 66v
1A: 177v
A/B: ~0v
1B: 177v
0B: 66v

which are all in the acceptable range. however, the LED closest to 1A is not lighting up. I am uncertain as to what I should do.
passed glow test. no other issues prior.

Im a newbie to this stuff, so any help/suggestions on what to do next would be appreciated!


Offline Paul Birkeland

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Reply #1 on: March 22, 2020, 07:23:22 PM
Was that LED lit up OK before this incident? 

Can you post a photo of the PCB?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline billyshears

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Reply #2 on: March 22, 2020, 09:06:26 PM
pretty sure but maybe somehow i didn't realize. see attached. let me know if you need more pictures!
« Last Edit: March 22, 2020, 11:34:01 PM by billyshears »


Offline Paul Birkeland

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Reply #3 on: March 23, 2020, 05:52:45 AM
Q1A is installed backwards.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline billyshears

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Reply #4 on: March 23, 2020, 10:21:37 AM
my brain did not let me see that. thanks so much!


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