Crack: voltage issues, leds don't light up [resolved]

Mickels · 1195

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Offline Mickels

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on: November 12, 2020, 07:56:33 PM
I built a Crack about 7 years ago, no issues and I still to listen daily.  A friend bought me another Crack kit and I figured I'd try some upgrades.  Spent almost 3x as long to build as the first one...and there are issues.  Go figure.  ::) I plan to install the speedball later so temp mounted the caps with extra long wire.

Passed initial voltage test
Passed glow test
Passed resistance test
Failed last voltage test, led not lit

1: .003v
2: .002v
3: .001v
4: .002v
5: .003v
6: .001v
7: 1.2v
8: .001v
9: .001v
10: .002v

I redid the first voltage test
6.2v at Terminal 9
175.3v at Terminal 12

Tubes glow

Per the manual and Paul's typical advice, I will reflow all the joints tomorrow aside from A3 and A8.  If that doesn't resolve, I will put the stock caps in and remove the Wima bypass.  If anyone spots any other issues, I'd greatly appreciate the help. 

The manual states we should fill all unused terminals on the sockets.  Is this necessary?  I dont want the solder flowing down to the bottom-hole joint.

Thanks in advance.



« Last Edit: November 13, 2020, 09:01:00 AM by Paul Birkeland »


Deke609

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Reply #1 on: November 13, 2020, 03:12:04 AM
Check that your meter is set to measure DC voltage, not AC voltage -- those tiny mV figures look like residual AC ripple on top of DC.

This won't explain why an LED isn't lighting, but might help narrow down the problem.

cheers, Derek


Offline Mickels

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Reply #2 on: November 13, 2020, 05:41:23 AM
Thank you.  My dmm was set to Vac.  I tested Vac at the iec and transformer afterwards.


Offline Mickels

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Reply #3 on: November 13, 2020, 05:48:36 AM
Forgot to ask.  Is there any signal run that would require a guage larger than 26?  I have some 24 that I can substitute.


Offline Paul Birkeland

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Reply #4 on: November 13, 2020, 06:10:24 AM
Terminal 12 is a grounded terminal, there shouldn't be 175V there?

What voltage do you get at B2?  B5?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Mickels

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Reply #5 on: November 13, 2020, 07:51:55 AM
Sorry I meant terminals 7 and 11 in the first test.  I will check b2 and b5 shortly.


Offline Mickels

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Reply #6 on: November 13, 2020, 08:49:58 AM
Sorry Derek, yes you were correct.  I had it set to vac.    Embarrassing...  i resoldered a resistor on the headphone jack and now the leds light up and passed voltage test.  Thanks for the help!


Deke609

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Reply #7 on: November 13, 2020, 01:45:12 PM
Congrats! No reason to be embarrassed. I still make that mistake all the time. Plus the mistake of forgetting to put in the fuse. Or forgetting the tubes -- that one gets me all the time.  And a whole host of others.

cheers, Derek


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