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October 17, 2021, 01:08:35 PM

Author Topic: New Crack Build  (Read 693 times)

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Offline jwilliams79

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New Crack Build
« on: September 09, 2021, 07:07:53 AM »
Just finished crack build failed resistance check. b6 and 9  showing  0 ohms.  Everything else passed. I thought it was because the wire moved while I was soldering b5 and  insulation got in the terminal. Fixed  that, it's still showing 0 ohms. Any ideas?

Offline Paul Birkeland

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Re: New Crack Build
« Reply #1 on: September 09, 2021, 08:38:16 AM »
Can you post some build photos? 

If 9 is showing 0 ohms, I would suspect that the wire that's supposed to leave 10 and go to the headphone jack is connected to 9 instead.

On the off chance that you have powered up the amp (which hopefully you haven't!) and the 100uF cap at 9 and 10 is backwards, it could fail and also give you a 0 ohm reading there.

Still, looking over build photos would be super helpful.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jwilliams79

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Re: New Crack Build
« Reply #2 on: September 10, 2021, 05:10:15 AM »
Thanks for the reply PB. I looked the amp over and moved some the sandblock resistor's wiring going in to 9L. I immediately got the proper resistances at 9 and b6. Then everything checked out but t22. I tightened down the transformer screws and got 0 ohms at t22. Voltage checks good ,leds light ,tubes light.   Nothing but static out of the headphone jack. how due I check to see if the problem's the  pot, vs headphone jack ,etc  ?

Offline Paul Birkeland

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Re: New Crack Build
« Reply #3 on: September 10, 2021, 05:13:39 AM »
Can you post your voltages at terminals 1-10 and some build photos?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jwilliams79

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Re: New Crack Build
« Reply #4 on: September 10, 2021, 06:01:29 AM »
Pics are coming PB. My voltages  Terminal 1:88.3v
                                                  T2: 177v
                                                   T3 0v
                                                    T4 177v
                                                     T5 82v
                                                      T6 0v
                                                       T7  109v
                                                        T8 0v
                                                         T9  109v
                                                          T10 0v
 
« Last Edit: September 10, 2021, 06:04:29 AM by jwilliams79 »

Offline Paul Birkeland

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Re: New Crack Build
« Reply #5 on: September 10, 2021, 06:05:30 AM »
You really should clean up the green wires that go to the 9 pin socket.  The one that goes to A9 is supposed to have only 1/4" of the jacket stripped off, but it looks like you have 3/4".  If that wire touches the chassis plate, it will destroy the power transformer.  The same goes for the other green wire going to A4/A5.

Did you have the same issue with the stock volume pot?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jwilliams79

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Re: New Crack Build
« Reply #6 on: September 10, 2021, 06:38:04 AM »
I still have the stock one. This wires up the same according  to members of the forum. I know you recommend the stock parts but I thought might as well just solder once. What are general ways to diagnose  pot vs jack. Do the rcas look decent  ? They seem loose when connecting a source. Using my phone as source.

Offline Paul Birkeland

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Re: New Crack Build
« Reply #7 on: September 10, 2021, 07:05:38 AM »
Yeah, I mean if things start pointing to the pot you'll end up having to remove it anyway to try the stock one, so swapping parts initially isn't always the best plan.  Are those the RCA jacks we provided? 

If you're using a 1/4" to 1/8" TRS adapter, those can cause problems.

Static and no audio in both channels with perfect voltages is what made me initially suspicious that possibly you got a balance pot by accident or something weird like that.

With the amp off and headphones plugged in, what resistances do you see at terminals 6 and 10?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jwilliams79

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Re: New Crack Build
« Reply #8 on: September 10, 2021, 07:25:31 AM »
T6 and t 10 both .025k using 2k range adjustment. Not a auto dvm.

Offline Paul Birkeland

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Re: New Crack Build
« Reply #9 on: September 10, 2021, 07:28:49 AM »
An auto DVM might be a good idea.  You're suggesting that the resistance reading there is 25 ohms, which seems somewhat improbable unless you're plugging in low impedance headphones.  Which headphones did you plug in?

With just a 1/4" to 1/8" adapter plugged into the amp, you would expect to see 2.49K at 6 and 10.
Paul "PB" Birkeland

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Offline jwilliams79

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Re: New Crack Build
« Reply #10 on: September 10, 2021, 08:05:48 AM »
10$ sonys to test the amp out. Used massdrop 600s as well. I expected less static with 600s but it was basically  the same.

Offline Paul Birkeland

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Re: New Crack Build
« Reply #11 on: September 10, 2021, 08:11:37 AM »
Can you send me a link to the pot you ordered or the part number?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jwilliams79

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Re: New Crack Build
« Reply #12 on: September 10, 2021, 08:25:07 AM »
Pb its the  stereo pot from audio note. I read on the forum where someone got the balance pot by mistake. So I made sure to get the stereo pot.

Offline jwilliams79

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Re: New Crack Build
« Reply #13 on: September 10, 2021, 09:26:44 AM »
Here's the part number : ANVPOT-81914

Offline Paul Birkeland

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Re: New Crack Build
« Reply #14 on: September 10, 2021, 11:01:48 AM »
I think you should put the stock pot in just to be sure.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man