Screwed up my Crack upgrade

flyfisher55 · 5600

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Offline flyfisher55

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Reply #75 on: May 06, 2019, 03:06:53 PM
Just a shot in the dark, but maybe resolder the legs of the transistor on the OB side. The circled leg looks a bit iffy in the photo (but could be perfectly fine).  I'd try soldering it from the top, tinning and putting the tip on one side of the leg/trace-hole and applying solder to the other side.  Might be worth a try
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Thanks Deke, I tried what you said. I've put three PN2907's into O1B. all three including original shorted one and two that I ordered  read differently than O1A.
O1A L&R = O.L M Ohms
       L&C =O.L M Ohms
       R&C =40.19 M Ohms

O1B L&R = O.L M Ohms
       L&C = O.L M Ohms
       R&C =00.00 M Ohms



Offline flyfisher55

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Reply #76 on: May 06, 2019, 03:28:54 PM
here are latest photos of small board.



Offline Paul Birkeland

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Reply #77 on: May 06, 2019, 03:53:20 PM
The other option is to use the repair service.  Many times the repair only requires resoldering all of the joints in the amp.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline flyfisher55

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Reply #78 on: May 07, 2019, 01:08:02 AM
After all this time and effort, sending it in for repair feels like throwing in the towel, Especially when we've confirmed that the unit was working prior to the upgrade and upon being restored to the original is once again operable. Is it an option to order another Speedball kit?



Offline flyfisher55

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Reply #79 on: May 07, 2019, 01:13:49 AM
I'm confused, Despite the fact that the unit is operational and reading within the correct parameters presently you still feel that the fault lies with bad solder points?



Offline Paul Birkeland

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Reply #80 on: May 07, 2019, 04:07:58 AM
I'm confused, Despite the fact that the unit is operational and reading within the correct parameters presently you still feel that the fault lies with bad solder points?
Potentially solder points on that small PC board.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline flyfisher55

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Reply #81 on: May 07, 2019, 04:13:17 AM
Do present resistance values have any relevance on parts being damaged? Are we we 100% sure the board it self is not the culprit? I'm willing to desolder every component and start from scratch.  I'm very interested in finishing this project but I'd like to do it without returning it for someone else to fix.



Offline Paul Birkeland

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Reply #82 on: May 07, 2019, 04:42:06 AM
The problem with simply saying "the board itself" is that it could just be a flaky solder joint on that board that's causing all that trouble.  We have never had a problem that turned out to be a production issue with a PC board, and dead transistors will cause a short that presents high voltage at the output.  You have no voltage at the output.  One cause for this would be a short to ground in the amp itself, which we have narrowed down to not being possible because the stock amplifier is working properly.  The other possibility is that a connection is not adequately soldered on the board, causing a complete lack of voltage on the output (and none of the associated heat of having a short).

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline flyfisher55

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Reply #83 on: May 07, 2019, 05:20:08 AM
That being the case, do my latest resistance readings reveal anything and should I replace any parts which may be causing the problem?



Offline Paul Birkeland

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Reply #84 on: May 07, 2019, 05:26:50 AM
You could request a replacement small Speedball board from the replacement parts e-mail. 


Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man