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sammichSID 5V Issue


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My sammichSID has been sitting in a box for while, and was previously working. I just took it out to hook it up, and it wouldn't turn on :(

I started doing voltage tests, and 9V/12V are all good on the bottom PCB, but there is an issue with 5V. I read 5V at the voltage regulator (labeled 1 in the bottom right of my picture), so that is good, but at the 5V pad of J2, I only read 0.02V. So the problem seems to be near the voltage regulator. I also only read 0.02V at all other 5V test points in the build guide.

Am I correct in thinking that I should also read 5V at C3 (labelled 2 in my picture)? If so, I only read a few mV there, which makes me think maybe the capacitor is the issue. But I'm not too knowledgeable in circuit theory so I'm not sure. Would appreciate any help!



Edited by skweeegor
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yes, you should read 5V on C3, C4 and J2. But based on your measurements the capacitors don't cause the problem (it would be a short, resulting into 0V at pin 1).

Sounds like a bad solder joint or broken track? What happens if you connect pin 1 and 2 with a short wire?

Best Regards, Thorsten.

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That did it! She's alive now. Thanks so much!

When I took a closer look, I did noticed some crusty stuff near C3, maybe old flux. Could it have eaten away at the trace? I guess I should give the board a good clean.

A noob question for you...I thought I could just solder pin 1 and 2 together to achieve the same thing, but this only gave me 5V at C3 and not further down. Yet using an actual wire as you suggest works. Why? In both cases the same connection is being made. 

edit: Just looked at my solder. It has RA flux which it claims is non-corrosive. 

Edited by skweeegor
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