LED not glowing [resolved]

jake111 · 1500

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Offline jake111

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on: March 20, 2019, 11:44:16 PM
Did the voltage test on the 1st PC board and the LED closest to IB is not glowing.

OA       76.5
IA        170.8
B-A/B   00.3
IB        171
OB       72.9
« Last Edit: March 21, 2019, 06:03:36 PM by Paul Birkeland »


Offline Paul Birkeland

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Reply #1 on: March 21, 2019, 04:11:28 AM
Can you post some photos of your build?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jake111

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Reply #2 on: March 21, 2019, 10:21:41 AM
Should I replace the stock pot? This one worked fine before the Speedball.


Offline Paul Birkeland

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Reply #3 on: March 21, 2019, 10:24:27 AM
It wouldn't hurt to put the stock pot back in, but it may not be necessary.  Can you unscrew the screws that hold the board on, flip it up, and take a photo of the underside? 

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jake111

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Reply #4 on: March 21, 2019, 01:36:53 PM
Photo:


Offline Paul Birkeland

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Reply #5 on: March 21, 2019, 01:52:23 PM
It probably wouldn't hurt to just reflow the joints on that side of the PC board. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jake111

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Reply #6 on: March 21, 2019, 04:28:58 PM
Reflowed and no change.


Offline Paul Birkeland

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Reply #7 on: March 21, 2019, 04:42:06 PM
Can you carefully measure the voltage on A2?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jake111

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Reply #8 on: March 21, 2019, 04:58:14 PM
I just swapped the LED with one from the other PC board and works now. I think I got a bad one.
A2 is 00.5 mv


Offline Paul Birkeland

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Reply #9 on: March 21, 2019, 05:00:04 PM
If they sit around for a very long time in a humid environment, they can absorb moisture and fail during soldering.  This process takes a very, very long time though, from what we have seen previously one user left his Speedball kit in a damp basement for 6 months and had some LED issues when he went to use them.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jake111

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Reply #10 on: March 21, 2019, 05:14:38 PM
Yep, that's it. The unstarted kit has been sitting in Hawaii since November and it's pretty humid here.
They're fine once soldered I hope?


Offline Paul Birkeland

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Reply #11 on: March 21, 2019, 06:00:29 PM
Ha ha, yeah that will definitely do it! 

Once they are soldered, you are good to go.  Somewhere there is a sheet of instructions for drying surface mount type LEDs in an oven, but honestly I would just order a pack of the spares and not worry too much about it. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jake111

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Reply #12 on: March 21, 2019, 06:02:52 PM
Thanks Paul


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