driver testing [resolved]

joralieu · 2025

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Offline joralieu

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Reply #15 on: April 24, 2024, 03:06:33 AM
Ok I have the resistors in the right spots now here is what I got.
A socket.             D socket
1a 519                 1a 519
Oa 298.                Oa 349
All the led's light up



Offline Paul Birkeland

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Reply #16 on: April 26, 2024, 10:44:18 AM
OK, well the side with 298V is likely working properly.  What are the Kreg voltages on the side with 349V at OA?  Does the 5670 glow on that side of the amp?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline joralieu

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Reply #17 on: April 26, 2024, 02:20:55 PM
The 5670 on that side lights up Kreg A 3.75V Kreg B is 15V



Offline joralieu

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Reply #18 on: April 30, 2024, 04:37:03 PM
Any further advice?



Offline Paul Birkeland

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Reply #19 on: May 01, 2024, 05:31:58 AM
You had said before that both sides light up...

On the side with the OA at 349V, can you report both Kreg voltages on that side?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline joralieu

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Reply #20 on: May 01, 2024, 08:55:43 AM
Kreg A 3.75V
Kreg B  15V



Offline Paul Birkeland

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Reply #21 on: May 02, 2024, 01:37:41 PM
Those voltages suggest that that C4S board should be working, so I'd be looking for missing jumpers or a broken wire that's not allowing the regulator to pull things down properly. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline joralieu

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Reply #22 on: May 02, 2024, 04:13:27 PM
Kreg b on the right channel is 7V kreg b on the left channel is 15V, is this right?



Offline Paul Birkeland

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Reply #23 on: May 03, 2024, 04:19:45 AM
What OB voltages do you see on each side?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline joralieu

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Reply #24 on: May 03, 2024, 05:29:38 AM
A side OB 174V
D side OB 176V



Offline Paul Birkeland

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Reply #25 on: May 05, 2024, 06:57:53 AM
7V is the correct value.  15V means that you have a bunch of current being sucked down somewhere else. 

On the 9 pin socket on the side with 15V, there is a little resistor that connects to the earth lug on the 5 pin terminal strip holding all the zener diodes.  What is the DC resistance between the star ground screw in the center of the chassis and that terminal where that resistor connects?  This connection not being 100% would prevent the 5670 regulator half from doing its job properly.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline joralieu

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Reply #26 on: May 05, 2024, 12:43:29 PM
I get O ohms there



Offline joralieu

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Reply #27 on: May 05, 2024, 02:25:45 PM
Would a bad 431 regulator on that side cause this?



Offline Paul Birkeland

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Reply #28 on: May 06, 2024, 05:44:59 AM
I've never seen a 431 fail in the way you're describing.  I suspect a broken wire or missing jumper on the C4S board.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline joralieu

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Reply #29 on: May 06, 2024, 04:43:50 PM
CS4 jumpers look good to me and don't see any obvious miswires or broken wires, checked them for continuity. Any clues where else I could look?  It is probably something simple , just not finding it.