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June 18, 2019, 08:02:16 am

Author Topic: Speedball D1 & D2 dark - Resolved  (Read 114 times)

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Offline phigits

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Speedball D1 & D2 dark - Resolved
« on: May 17, 2019, 03:33:32 pm »
Meter readings
OA - 69
OB - 40
G - 0
B+ - 79

D1 and D2 LEDs are dark.

The small board readings were fine before the large board was fitted.  Now they are:
OA - 42
1A - 78
B-A/B - 0
IB - 78
OB - 69

I don't see anything obvious so I'm hoping someone can point me in the right direction.
« Last Edit: May 18, 2019, 10:11:46 am by phigits »

Offline Paul Birkeland

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Re: Speedball D1 & D2 dark
« Reply #1 on: May 17, 2019, 04:06:57 pm »
Your TIP50 transistors are improperly mounted and shorting out the HV supply.  Please see the note in enormous text on page 22 and also note that we have a link to a video because it is so critical that these steps are followed carefully.

I would also very, very strongly suspect that you have a PN2907 in backwards on the small board.

-PB
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline phigits

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Re: Speedball D1 & D2 dark
« Reply #2 on: May 17, 2019, 05:17:47 pm »
Damn.  100% ass-backwards on the TIP50's.  Both PN2907 are correct.

Ordering new parts.

Thanks, Paul.
« Last Edit: May 17, 2019, 05:20:46 pm by phigits »

Offline phigits

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Re: Speedball D1 & D2 dark
« Reply #3 on: May 17, 2019, 05:42:08 pm »
Wait a minute...the TIP50 transistors look correct.  But I see the D1 and D2 LEDs are upside down...
« Last Edit: May 17, 2019, 05:44:41 pm by phigits »

Offline Deke609

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Re: Speedball D1 & D2 dark
« Reply #4 on: May 17, 2019, 06:00:28 pm »
Maybe post a pic or two of the board just to be sure.  Fresh eyes are better at picking out possible problems.

cheers,

Derek
Derek
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Roon Intel NUC ->  Yggdrasil DAC -> BeePre (w/ BeeQuiet and JJs)  -> Stereomour IIs (2A3 and 45 Conversion - both fully upgraded)  -> Audeze LCD4

Offline phigits

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Re: Speedball D1 & D2 dark
« Reply #5 on: May 18, 2019, 08:39:56 am »
The LEDs and voltages are ok.  Now I'm just chasing down a buzz in the right channel.  Checking all the joints again.

Offline phigits

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Re: Speedball D1 & D2 dark
« Reply #6 on: May 18, 2019, 10:11:10 am »
Found a post from PB where he repaired a buzz in one channel by removing excess solder from the center pin of the RCA jack.  I did that and viola, the buzz is gone.