new speedball upgrade blowing fuses

Erekj3775 · 440

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Offline Erekj3775

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on: November 11, 2024, 03:37:49 AM
Hello,

I am just installing a speedball upgrade. All resistance and voltage reading from stock crack were within tolerance. I installed and tested the small board and all voltages were on and LED's lit. When I went to install large board OA and OB resistances were over limit. Plugged in the unit and nothing.  Unplugged unit and checked fuse. It was blown. Reflowed solder at connections for large board and tried again. Fuse blew again. Here are the resistances I’m getting. Thanks for helping.

Small speedball board
OA - 317.6k
1A - increasing resistance
B/A-B - 0k
1B - increasing resistance
0B - 310.1k

Large speedball board
0B - over limit
G - 0k
B+ - increasing resistance
0B - over limit

Thanks again for helping me troubleshoot this issue.

Erek


Offline Erekj3775

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Reply #1 on: November 11, 2024, 03:43:15 AM
Here are some pictures of the build.


Offline oguinn

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Reply #2 on: November 11, 2024, 04:13:04 AM
It’s hard to tell from the photos, but are your PN2907As oriented correctly?

Jameson O'Guinn

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Main System: Schiit Bifrost MB, Rega Planar 6 with Exact cartridge, Eros 2, BeePre, Kaiju/Stereomour II, Jagers, Mainline

Desktop System: Crack with Speedball

Offline Erekj3775

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Reply #3 on: November 11, 2024, 05:04:02 AM
Thank you.  Yes they are installed backwards.  Will correct and see if that fixes the issue.


Offline Paul Birkeland

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Reply #4 on: November 11, 2024, 07:08:03 AM
You also have not sufficiently soldered your PC boards.


Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Erekj3775

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Reply #5 on: December 10, 2024, 05:42:31 PM
Hello
Finally got a chance to work on the issues with my amp. I fixed the PN2907A’s. I also looked into the soldering on the boards. Here are some pics of the boards now but I am still blowing fuses as soon as I power on.

Thanks for taking a look.

Erek


Offline Paul Birkeland

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Reply #6 on: December 11, 2024, 04:30:22 AM
If you take the Speedball boards and tubes out, then leave the loose wires poking up, does the fuse still blow? (I'd imagine it will)

If it does, then there's something wrong with the build excluding the Speedball, which is most likely.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

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