Driver Testing 0 voltages [resolved]

hpleung · 1245

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Offline hpleung

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on: May 29, 2022, 03:45:26 PM
Hi,

I am currently trying to do the driver testing.

IA = 482 volts
OA = 300 volts

However, 46U <--> Safety ground

Gives close to 0 voltages. Trying both sides and same results (i.e. 32U <--> Ground)

Any idea on where I should look? Feels to me like a missing connection.

« Last Edit: May 31, 2022, 05:08:23 AM by Paul Birkeland »



Offline Paul Birkeland

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Reply #1 on: May 30, 2022, 04:11:35 AM
I see substantial damage to one of your filter caps and a blackened power supply resistor, is there a little more to the story? 

Can you post some more photos, ideally of the top and bottom of the PC board and the 9 pin socket wiring?  The output of the driver C4S will stay at 0V for a period of time before slowly ramping up, which is the intended operation of the soft-start circuitry. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline hpleung

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Reply #2 on: May 30, 2022, 07:13:44 AM
Hi,

Yes, I purchased this limited edition (the bronze color one) one out of Audiogon. It looks unused when I received it except for the capacitor dent as you mentioned. The "blackened" resistor is just a tape I stick on.

Attached the pictures requested.

I waited for 1 minute and the voltage still stayed at 0 volts.

Thanks.
« Last Edit: May 30, 2022, 07:15:26 AM by hpleung »



Offline Paul Birkeland

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Reply #3 on: May 30, 2022, 07:19:55 AM
Well the kit is built with stranded wire, and you may have some little strand poking out that's touching something it shouldn't. 

Why is there tape around a resistor?  Can you return this kit to the seller?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline hpleung

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Reply #4 on: May 30, 2022, 07:25:44 AM
Hi,

I think the seller purchased the kit directly from Bottlehead and never used it. It looks legit when I received it with plastic around the parts. I don't think it was ever used.

I chose the stranded wire although the kit came with solid core wire. Perhaps a mistake on my part but I notice often the solid core wire would break.

From the pictures; are you able to tell if there are any obvious connection that is missing? I will go and inspect if there are any stranded wire sticking out.

Thanks.



Offline Paul Birkeland

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Reply #5 on: May 30, 2022, 07:42:23 AM
You're missing a transistor on the B side of the PC board.

Yes, stranded wire is not a good idea.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Doc B.

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Reply #6 on: May 30, 2022, 02:19:23 PM
Solid core wire breaks because it is being improperly stripped.

Watch the video starting at 8:45 to 12:10.


Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline hpleung

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Reply #7 on: May 30, 2022, 05:05:52 PM
Thank you both. The missing transistor was it. It works now.