C4S voltage check failing [resolved]

cacofonix · 11061

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Offline cacofonix

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on: December 26, 2023, 01:38:24 PM
Hi

When performing the voltage checks after assembling the C4S board I get the following readings
1=151.3
11=151

6=124.1
16=148.1

I've traced through the manual steps and re-flowed the chassis connections but it hasn't addressed the high voltage on 16

Any thoughts on what might be wrong and what I could do to diagnose and rectify?

Thanks
« Last Edit: January 08, 2024, 07:50:55 AM by Paul Birkeland »



Offline cacofonix

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Reply #1 on: December 28, 2023, 11:16:50 AM
I took a few more photos including of under the board, and the side with the voltage issue

Maybe it will help find the culprit




Offline Kris

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Reply #2 on: December 28, 2023, 12:47:34 PM
Looks like you have D1 on B side of C4S board reversed.



Offline cacofonix

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Reply #3 on: December 28, 2023, 04:10:34 PM
doh!

You're right @Kris - thanks for catching that.

I didn't see it even after looking at many times.

I can't wait to fix that mistake (but also scared of trying to remove and solder that diode with clipped leads)



Offline Kris

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Reply #4 on: December 28, 2023, 05:26:42 PM
but also scared of trying to remove and solder that diode with clipped leads

Yeah, I wouldn't even try to reuse that LED. They are too fragile and most likely will not survive that amount heat.
Just contact Bottlehead and order replacement.



Offline Paul Birkeland

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Reply #5 on: December 30, 2023, 06:16:35 AM
I would also suggest a lot more heat and some more solder on the Q2 transistors and the R2 resistors on that board.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline cacofonix

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Reply #6 on: December 30, 2023, 07:13:55 AM
Yeah, I wouldn't even try to reuse that LED. They are too fragile and most likely will not survive that amount heat.
Just contact Bottlehead and order replacement.

Thanks Kris. I ordered a pack of replacements

I would also suggest a lot more heat and some more solder on the Q2 transistors and the R2 resistors on that board.

Thanks Paul

I was definitely tentative with the heat and the solder on the board thinking that my ham-fistedness would either damage a component or I'd create a solder bridge or something. I will apply more solder to those and turn the heat up on my soldering iron



Offline Paul Birkeland

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Reply #7 on: December 30, 2023, 08:16:06 AM
You will really need your iron set at max heat to get a proper solder joint on the center leg of the MJE5731A transistors, as that is connected directly to the metal tab which is on a big heatsink. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline cacofonix

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Reply #8 on: January 08, 2024, 07:33:05 AM
Just wanted to follow up and not leave this thread hanging.

I got my replacement leds and made the fix that Kris caught.

I also applied more heat and solder to the connections as Paul suggested.

My BeePre2 passed all voltage checks and is fully operational.

Thank you for your help