• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

2270 Volume pot cleaning help

sanjib

sanjib

AK Subscriber
Subscriber
Hi
I have 2270 that I am restoring. The volume pot has nasty static in the right channel that is in the front gang (gang away from the shaft. I have tried lots of D5, D100, and F5 for 2 days but it did not help. I never opened a volume pot to clean it. But this time decided to go for it.
I have opened it and cleaned it with Q-tip, but I am not sure it is cleaned enough to put pack.

I have attached some pics and if anyone recognizes any flaw like still needing to clean or the wiper is not in good contact please let me know. I just make sure there is nothing to be done before putting it back on.

Thank you in advance.
20220403_115650.jpg 20220403_115714.jpg 20220403_115746.jpg 20220403_115800.jpg
 
Last edited:
Register to hide this ad
Did some more cleaning on the top of the wiper and I realized the black stuff on it is gunk! But it is bit difficult to clean all the 3 sections of the wiper. Am I good here or need to clean all black coating from the top of the wiper?

20220403_123221.jpg 20220403_123243.jpg
 
I would try a q-tip and some IPA. Alcohol not beer. You can drink a beer while you clean it but don't put any in your pot.
After that flush it with some fader lube.
 
Jonstigator said:
I would try a q-tip and some IPA. Alcohol not beer. You can drink a beer while you clean it but don't put any in your pot.
After that flush it with some fader lube.
Click to expand...
Thanks!
Yeh, did that and put it back in and further diagnosis reveals that the nasty static in the right channel with increasing the volume is not probably from pot but rather from the right pre-amp board! Need to check the transistors there as all are new caps.
 
Last edited:
sanjib said:
Thanks!
Yeh, did that and put it back in and further diagnosis reveals that the nasty static in the right channel with increasing the volume is not probably from pot but rather from the left pre-amp board! Need to check the transistors there as all are new caps.
Click to expand...

I always replace those trannys
 
I replaced 2SC1000 with KSC 1815 but 1815 (~200) has a very low gain compared to 1000 (~450) and 2SA493 was replaced with KSA1015.
 
Always rebuild the preamp if the static isn’t going away with Deoxit. The preamp can leak voltage and you end up with static that’s unrelated to the control being dirty.

You can use KSC1845 and KSA992 for the preamp section. They will work fine.
 
EastPoint said:
Always rebuild the preamp if the static isn’t going away with Deoxit. The preamp can leak voltage and you end up with static that’s unrelated to the control being dirty.

You can use KSC1845 and KSA992 for the preamp section. They will work fine.
Click to expand...
That is what I think may be happening. But, even after changing all caps and transistors, it is still happening. I am getting a considerable amount of DC (2mV at volume zero gradually increasing to almost 0.8V at volume at 12 o'clock position) at Pin J401 and J402. Can any resistor be a culprit?
 
Can the equalizer board leak DC to preamp and eventually to volume pot?
Equalizer is all original?
 
The problem is solved. Measuring all the voltages in the right pre-amp led to C401 which should block the DC was not doing its job. There was a tiny microscopic bit of solder shorting it to a resistor in the vicinity. The pot is fine and working without any static.
 
You must log in or register to reply here.
Back
Top Bottom