Speedball install voltage issues [resolved]

Dr. Soot · 1105

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Offline Dr. Soot

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on: March 10, 2023, 05:31:31 AM
Hi all, I am in the process of installing the Speedball upgrade.  I just finished installing the first board and went through my voltage checks.  Here are the results;

OA -184 V
IA - 185 V
B-A/B - 0 V
IB - 185 V
OB - 184 V

OA and OB should be half of the voltage I am reading.  I followed the flow chart and determined that the 12AU7 does glow, but the LEDs on the bottom of the 9 pin socket do NOT glow.  I went over each of the solder points on the 9 pin socket to make sure they were OK, and they appear to be.

Any help is much appreciated.  Happy to upload some photos, just not sure what to take a photo of.
« Last Edit: March 15, 2023, 04:03:09 PM by Paul Birkeland »

Cheers,

Pedro

Offline Paul Birkeland

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Reply #1 on: March 10, 2023, 05:34:32 AM
Can you post photos of the top and bottom of the small PC board?

I would expect that you don't have the center legs of the MJE350s well soldered. If your 12AU7 glows, it would be very important to leave the LEDs on the 9 pin socket alone.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Dr. Soot

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Reply #2 on: March 10, 2023, 05:46:22 AM
Here you go.

Cheers,

Pedro

Offline Doc B.

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Reply #3 on: March 10, 2023, 06:01:28 AM
Look at the center leg of each MJE350 on the top side of the
PC board photo. There needs to be solder between the leg and the solder pad. Watch this starting at about 36:05  -


Dan "Doc B." Schmalle
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Bottlehead Corp.

Offline Dr. Soot

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Reply #4 on: March 10, 2023, 06:08:09 AM
Many thanks Doc. I will follow up if that works.

Cheers,

Pedro

Offline Dr. Soot

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Reply #5 on: March 10, 2023, 06:17:22 AM
Still getting a voltage in the mid 180's at OA and OB.

Cheers,

Pedro

Offline Paul Birkeland

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Reply #6 on: March 10, 2023, 06:18:59 AM
Can you carefully measure the voltages at A3 and A8?  Can you repost the photos of that board?

Also keep in mind that if you try to just add solder from the other side of the board rather than reheating the joints from the bottom, you are unlikely to resolve the issue (I just mention this because we have seen it happen a bunch).

Paul "PB" Birkeland

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Offline Dr. Soot

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Reply #7 on: March 10, 2023, 06:21:17 AM
OK, will make sure the board is properly soldered and then I will take photos and measure A3 and A8.

Cheers,

Pedro

Offline Dr. Soot

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Reply #8 on: March 10, 2023, 06:37:09 AM
A3 = 180.6 V
A8 = 182.2 V

Cheers,

Pedro

Offline Paul Birkeland

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Reply #9 on: March 10, 2023, 06:49:12 AM
A3 and A8 are pins on the 9 pin socket.  You would be the first person in the history of the Crack to measure voltages like that at those pins...

Could you remove that board again and post photos of your stock Crack build without it?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Dr. Soot

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Reply #10 on: March 10, 2023, 06:53:30 AM
I assume the Crack should be plugged in for these measurements, correct?

Cheers,

Pedro

Offline Paul Birkeland

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Reply #11 on: March 10, 2023, 06:56:50 AM
Yes, you should not get any DC voltage without the amp plugged into the wall and powered up.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Dr. Soot

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Reply #12 on: March 10, 2023, 07:02:12 AM
ok, here are photos of the 9 pin socket and the stock build


Cheers,

Pedro

Offline Paul Birkeland

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Reply #13 on: March 10, 2023, 07:03:44 AM
Could I see an overhead of the whole build?

A4 and A5 don't look well soldered.

If you have 180V at A3 and A8, then I would be very, very surprised if your stock build functioned properly and passed its original voltage checks.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Dr. Soot

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Reply #14 on: March 10, 2023, 07:06:21 AM
When you say you want to see overhead, you mean right side up?  It worked fine for the last year plus that I have had it.  I will resolder all the pins on the 9 pin socket.

Cheers,

Pedro

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