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Old 30th April 2011, 06:45 PM   #11
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One trippot is upside down ...



Corect Trimpot orientation:

Click the image to open in full size.

Last edited by komigenie; 30th April 2011 at 06:50 PM.
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Old 30th April 2011, 06:50 PM   #12
AndrewT is offline AndrewT  Scotland
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Does that mean he did not get his resistance meter out and check the Vr setting to zero before he powered up?
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Old 30th April 2011, 06:55 PM   #13
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I checked both sides, and it shouldn't matter what direction they are, that just changes what way you turn the adjuster to move the voltage a specific direction
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Old 30th April 2011, 07:02 PM   #14
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Quote:
Originally Posted by crazycody1993 View Post
I checked both sides, and it shouldn't matter what direction they are, that just changes what way you turn the adjuster to move the voltage a specific direction
OK, on PC board 2 pins on rtim pot are conecter -Hmm, OK ... you have 0 ohm before you solder or - after you solder on PCB ?
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Old 30th April 2011, 07:06 PM   #15
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After I soldered it to the board.
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Old 30th April 2011, 07:19 PM   #16
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Looking @ the colors on blown resistors, seems to me - is not 47r, if i compare colors on resistors on another side ..
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Old 30th April 2011, 07:26 PM   #17
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Just before the very first time you turn it on, the easiest test points to measure are across R3 and R4. Resistance readings should be both zero...
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Old 30th April 2011, 07:54 PM   #18
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I'll have to double check that. Other then possibly having the POTS wrong, I can't see any issues on the board.
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Old 30th April 2011, 08:06 PM   #19
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Default I'm using the Jim's boards, without any problems

Quote:
Originally Posted by crazycody1993 View Post
I'll have to double check that. Other then possibly having the POTS wrong, I can't see any issues on the board.
They were a gift, and I stuffed them into my amp. It's working fine.

Position of the trim pots isn't vital--as long as you set them for minimum resistance when you first power up the amp....and then set the biases. The way I have my trimpots inserted, the LEFT one is minimum resistance when fully clockwise; the RIGHT one is minimum resistance when fully counterclockwise.....but BE CAREFUL, this is a function of how you inserted the trimpot into the PCB. Best, best thing to do, is to set both pots to minimum resistance using an ohmmeter (or the ohms function on a DMM).

The pic in post #11 is of my amp, but you can't see many details from this photo. I'll be in my home later today, and will grab better pics of one of my Jim's boards, and will post it. I'll also compare your PCB wiring (your pics) to mine.

Did you fully test your power supply for proper rail voltages, before you hooked up the amp PCBs?

Ken
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Old 30th April 2011, 09:36 PM   #20
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Actually no, I didn't test my supply voltages. I should have done that as soon as it was together. Will improper voltages make significant differences in setting it up?
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