I was just in the process of repairing a punch P300-1 amp and after replacing the audio transistors I wanted to set the bias pot all the way down, when I attempted to break the blue gunk free from the pot, I broke the bias pot. Does anyone know what the part number of this component is or what the range of the pot is so I can attempt to replace it. Thanks,
Kelvin
Kelvin
After further review, I see the number 202 is on the bias pot which looks to mean it is a 200 Kohm trimmer pot. i found this on mouser and thinking it might be what I need.
3309P-1-204 Bourns | Mouser
3309P-1-204 Bourns | Mouser
I found a 10KOhm pot at Radio Shack that I have decided to try, but as I am thinking about it, this may not work. I was thinking of the in terms of the concept where if it sweeps from 0-10Kohms that this would cover my 0-2KOhm range. But since this pot has 3 legs on it, I am wondering if it will be working more like a voltage divider where the wiper leg and one contact will be a portion of the total resistance and the other contact and wiper leg will be the remainder of this resitance. Not sure how restrictive on the current the 10K pot vs the 2K pot will be in this application.
You should order the correct pot. If you simply want a pot for testing, buy a different type of the correct value and hard-wire it to the board.
Thanks Perry, I was thinking that would be to correct answer. I actually had the amp going but was having a hard time turning the pot to dial in the bias, i got greedy and wanted to tweak the pot some more to better dial in the bais when I tried to pry more of the glue off rotary part so I could have more surface area to turn the dial then the rotary dial broke away from the pot. I guess it is another lesson learned the hard way. I wish they wouldn't have used so much glue at the factory to seal the pot, not sure if there may be a better technique to break it free, but brute force is obviously not a good technique.
Kelvin
Kelvin
I generally carefully squeeze the sides of the pot to break the epoxy bond between the knob and the frame. It's generally easy to turn after that, even if you don't clear the center of the knob.
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