Can Pot Be Fixed/Cleaned

[TinCanAlley]

The volume pot is from a '74 Zenith TV and it doesn't act the way a normal dirty pot would (or at least from my limited experience). All pots I've dealt with before that are "dirty" have the signature "scratchy" sound when rotating it. This one isn't really scratchy, it's more unstable in volume level as I'm rotating it. As I turn it up, it gets louder, but then starts to get muffled and if I wiggle it, it goes in and out. Once I get it to the level I want, I wiggle it until it stays, but sometimes gets muffled again. Is this a sign of being dirty, or is it damage to the pot's internals?

I'm hoping it is fixable as all searches for a replacement have come up empty.

Thanks!

[Electronic M]

You won't know till you try. Sometimes very dirty pots will do that, sometimes that's a sign the carbon trace is open.

If it's a slide pot those tend to be worse than knob styles from a reliability standpoint. Repairability is all over the map...Some sliders respond poorly to cleaning (cleaner soluble carbon track), some the track wears out under the slider fingers, and you can bend the fingers to track the good part... Some the Metal contact breaks off the slider and you're left drilling and tapping for some ultra miniature screws one ace hardware out of 5 in the area varies as a specialty line.

Knob style pots can about always be sourced or modify from something. Just need to know resistance and taps and the shaft end style and lengths and any additional switches or pot sections.

[bgadow]

There used to be a strong aftermarket for pot replacement; I have a nice box full of stuff from Centralab that I got from a retired Sears tech. With them you can build your own, including adding a switch, tone control, add the length of shaft you need. Still, I hardly ever have just what I need! I suspect for a set like yours there was some aftermarket availability of an exact replacement but it would take some digging. Do you have the Photofact? It would list whatever was available at the date of publishing. If you have the OEM part number we can help look.

[TinCanAlley]

Okay, I pulled the assembly out and will attempt to deoxit them. The color and tint controls are also a bit touchy and unstable, but nothing like the volume. Since I've ever only heard a scratchy pot, I wasn't sure if what I'm experiencing is a pot to far gone, that's why I came here before I dug into the section of the set that's a rat's nest of wires. Guess it wasn't all for nothing as now I can get the remote control board out and check it for my power on/off issue.

The pot has only one part# listed in the service manual and I've not been able to find it. It's 63-10263 and 40K.

[TinCanAlley]

Does anyone know if the volume pot is linear or logarithmic on 70s Zenith sets? I cleaned this pot and tested it with my DMM and if I turn it slowly from start position, it starts at 40 and works its way down at a steady pace until it reaches around 20 and then it speeds up until it hits around 9 and slows back down. It does the same in the reverse direction. Since I have the set apart, I can't put it back in and test it in real time.

I read that audio pots can be linear or logarithmic and there is usually and "A" or "B" on it to note which, but this pot has no such marking.

It's the 63-10263 and is 40K.

[old_tv_nut]

My guess is: volume pots are usually logarithmic for audio reproduction uses, but sometimes linear for musical instruments.

[Findm-Keepm]

Originally Posted by TinCanAlley

Does anyone know if the volume pot is linear or logarithmic on 70s Zenith sets? I cleaned this pot and tested it with my DMM and if I turn it slowly from start position, it starts at 40 and works its way down at a steady pace until it reaches around 20 and then it speeds up until it hits around 9 and slows back down. It does the same in the reverse direction. Since I have the set apart, I can't put it back in and test it in real time.

I read that audio pots can be linear or logarithmic and there is usually and "A" or "B" on it to note which, but this pot has no such marking.

It's the 63-10263 and is 40K.

What Chassis?