How to dissemble this volume POT

[JoeDotCom]

mine was exremely noisy, did this, quiet as a mouse:thmbsp:

http://analogattitudes.freeforums.org/technics-su-8600-volume-de-ox-by-drilling-t207.html

Thanks for the input AK47, but i am not sure you read the whole thread. I started with the holes drilled and have moved to much more invasive tactics. Unfortunately I think the circuit board inside my pot is damaged.

Some people drill holes... I took out a wall.

 

[BinaryMike]

As a "quick" fix, can I go buy this $4 100K stereo volume pot at radio shack?

That pot does have loudness taps, but the lower track resistance is a bit of a conundrum. If I was doing this on a temporary basis, I think I would just solder it in without attempting any sort of compensation. It's likely to sound quite good.

 

[JoeDotCom]

That pot does have loudness taps, but the lower track resistance is a bit of a conundrum. If I was doing this on a temporary basis, I think I would just solder it in without attempting any sort of compensation. It's likely to sound quite good.

Thanks for the info. What do you mean by "lower track resistance"?

i don't use the loudness feature.... does that mean i can get away with a 2 or 3 pin POT?

 

[qsaudio]

A regular looking pot will have a fourth terminal.And no, you should have the same resistance value, and the same type of pot.
The little clicks are BAD i hate that, just find a good pot, and forget the knob looking good part.

 

[BinaryMike]

Thanks for the info. What do you mean by "lower track resistance"?

i don't use the loudness feature.... does that mean i can get away with a 2 or 3 pin POT?

The putative replacement has 100K track resistance, vs 150K in the original. This might affect LF response and distortion due to greater loading of the upstream stage, and it could shift the loudness contour. I doubt if you will hear any difference. Well-designed equipment is relatively immune to loading effects because pot manufacturing track resistance tolerance is generally quite broad, and good designers always account for it.

If you don't plan to connect the loudness taps, then pots with three pins per section are adequate. Two-pin 'pots' are just rheostats, and won't work in this circuit.

 

[JoeDotCom]

The putative replacement has 100K track resistance, vs 150K in the original. This might affect LF response and distortion due to greater loading of the upstream stage, and it could shift the loudness contour. I doubt if you will hear any difference. Well-designed equipment is relatively immune to loading effects because pot manufacturing track resistance tolerance is generally quite broad, and good designers always account for it.

If you don't plan to connect the loudness taps, then pots with three pins per section are adequate. Two-pin 'pots' are just rheostats, and won't work in this circuit.

Thanks for the info Mike (and everyone else). I am learning a 150K stereo volume pot is tricky to come by. I will give my 100K (4 pin) radio shack pot a spin.

 

[JoeDotCom]

IT LIVES! Thanks to all for your guidance!

installed the 100K Radio Shack Pot (link earlier in thread) and it works great! I needed to create some 'legs' to make the pot fit on the circuit board. Lucky i had the leg-trimmings from the components from my SX-980 powersupply recap on hand still. So I added the legs to the POT and lined up the wiper and two outer connections where pins 123 were on the old pot. I also needed to bend the legs so that the front of the pot was lined up with the front of the circuitboard. It looks a little precarious in teh picture, but those legs are pretty stiff, so I am not too concerned about them getting bent / shorting, though I may still go back and insulate them. The the volume does jump up pretty quick when i move from 0 to a minimal listening level, but it is pretty easy to dial in a comfortable volume.

I also tried hooking up the 4th pin on the pot to the loudness connection. It was interesting to hear. With the 4th pin connected, the volume knob output no sound for the first 30 degrees or so, then began giving volume after that. With the loudness switch engaged, i could hear the "loudness signal" (just the bass/treble that is added in to the normal sound) start ramping up as soon as i started rotating the pot. So it was JUST bass/treble for the first 30 degrees or so, then the regular volume kicked in and began to catch up w/ the "loudness signal". I never knew how a loudness circuit worked, so this was a neat decomposition to hear.

Anyway, the loudness thing was neat but obviously far from enjoyable to listen to. So I disconnected it, leaving just the 3 main pins connected and the Loudness circuit on the amp disabled. (I am assuming it is disabled since that 4th pin is disconnected and the button does not do anything anymore as far as I can hear.)

I still need to get the knob back on there. I read you can get joining sleeve of some kind to extend the shaft. then hopefully i can find an extension / tip that will connect with the original volume knob.

(photos to be uploaded in a moment from my phone)

Here they are...