No signs of life after voltage test passed [resolved]

eabbott · 2486

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Offline eabbott

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on: October 08, 2023, 09:52:57 AM
Hi.  Working with my son to put a crack kit together.

Glow test passed.  Resistance checks passed.
We plugged in and checked the first few voltages in the list and none were correct.  LEDs are not lit and tubes did not glow.

We unplugged the unit and inspected all the solder joints and touched them up if they looked poor.  We went back through every connection and found 2 mistakes.  We found 2 components installed incorrectly - one rectifier (between 19 and 21) and one electrolytic cap (between 20 and 21).  Fixed those.  Everything else was ok.  Plugged power back in and checked the first few voltages (e.g. Terminal 1, 2, 3, 4) and the voltages are mostly zero volts DC.  LEDs still not lit and tubes still did not glow.

I'm concerned I may have damaged the transformer.  But, I see pretty much no signs of life.  If my suspicions may be correct, what can I do to check the transformer?  Or, what other things can I do to debug this?


Thanks.
« Last Edit: October 11, 2023, 02:56:06 PM by Paul Birkeland »



Offline Paul Birkeland

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Reply #1 on: October 08, 2023, 09:53:43 AM
I think you've blow the fuse and I would check that next.  If you blow up the transformer, your nose will tell you.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Paul Birkeland

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Reply #2 on: October 08, 2023, 09:54:32 AM
Oh also if you replace the fuse and it just blows again, the UF-4007 that was installed backwards may have turned itself into a piece of wire.  Thankfully that backwards diode probably protected the capacitor from its miswire.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline eabbott

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Reply #3 on: October 11, 2023, 12:32:41 PM
Yep, that was it.  Just got replacement fuses and everything works now.  Thank you!!