doubt on resistance check

giampi97 · 1251

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Offline giampi97

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on: June 02, 2018, 12:32:38 PM
I' am writing this post because i was doing the final resistance check e it says that terminal 10 should have a 0 resistance with the ground, but how can it be 0 and not 2,49k, since it is connected with the white cable to the upper lug of the headphone jack that is connected to the ground through a 2.49K resistance?
Thanks, Giampietro

Giampietro Fabrizio Bonaccorsi


Offline Paul Birkeland

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Reply #1 on: June 02, 2018, 12:44:35 PM
The headphone jacks shorts the 2.49K resistors to ground when no headphones are plugged in.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline giampi97

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Reply #2 on: June 03, 2018, 06:19:05 AM
Ok, then i don't know what is the problem. I have a full built crack (it's the first time i build an amp) and all the resistance and voltage checks are ok. Unfortunately I hear a loud disturbing noise (i tried it in different places, so it is not an external disturb). The strange thing is that if a give a little bump to the amp, the noise disappears for few minutes and then comes again.
Could it be a problem of cold joints?

Giampietro Fabrizio Bonaccorsi


Offline Paul Birkeland

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Reply #3 on: June 03, 2018, 07:20:43 AM
Yes, that sounds like a cold joint or a joint that hasn't been soldered at all.  The most common joint that's problematic in the Crack is where the black wires meet at the headphone jack.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man