Bottlehead Kits > Kaiju Stereo 300B amp

Issue with A Side C4S Board A [resolved]

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giggsy:
Hi,

Have an issue with the voltage through 32U after attaching the board.

Let me preface by saying I accidentally broke the 215 1/8 watt resistor from A3 to the center socket pin when working on A4. I had a replacement resistor to hand but although the markings are the same, the size of the resistor is larger than the ones supplied (see pic) so it could simply be that i used the wrong resistor.

My issue is the voltage at 32U measures about 98V. By turning the potentiometer I can get it up to 100V.
On the D side 46U initially read 158V but was easily adjusted to 175V.

Here are some readings I took

         A Side     D Side
IA        508v      508v
OA       295v      296v

32U       ~98v   
46U       158v adjusted up to 175v

On A board
Kreg on A side = 6.88v
Kreg on B side  = 6.75v
voltage across 4.99k Resistor = 2.47v
 

Paul Birkeland:
Turn the blue trim pot ten turns clockwise, then measure Kreg A.  Now turn the trim pot ten turns counter-clockwise and remeasure the voltage on Kreg A.  Let us know what those voltages are.

giggsy:
Turning 10x clockwise, kreg went down to 4.95v.
Turning back 10x counter-clockwise took the kreg back to 6.88v

Paul Birkeland:
Can you post a photo of the top of the board in question?

giggsy:
Thanks for helping Paul.
I've attached some pics of the board.

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