Locating odd sized potentiometer

[nevetslab]

Extracting broken pot shaft from rotor

Are you sure? I've had success more often than not popping these off and snapping them back on again. You may have to file the crimped metal a bit, but usually they still stay put when reassembled.

Following g1's lead, I dug out one of my broken shaft pots, pried off the cover, found on this pot the shaft/rotor assembly came free from the bushing casting and the resistance wafer. Sometimes that isn't the case, as there can be a step in the knob-end of the shaft that's larger than the shaft dia passing thru the bushing. I don't think that's the case on your broken pot.

Anyway, I took a series of photos, beginning with cutting at the flared shaft end that protrudes thru the nylon rotor assembly.



If you have any other broken pots, I'd suggest practicing the procedure before committing to the one that counts. After I began prying the nylon rotor up, pivoting off of my small machinist vise with a Wiha bladed screwdriver, it finally began lifting up. During the filing process, I slipped off the top of the rotor, and dinged the multiple finger wipers of the pot, so those parts are very fragile and easily broken, so beware.

The flatted rotor end of the shaft is very tight fitting, so g1 is quite correct in that they would stay put after reassembly. Sorry for the out-of-focus shot looking sideways at the shaft-rotor assembly...camera focused on the nearest surface of the vise, not the shaft/rotor.

But anyways, he's right......with care, you CAN disassemble these. Now, coming up with the replacement shaft??? Might be that further machining is needed, with grinding the broken end flat/perpendicular to the shaft, marking & center-punching the center of the shaft so you could pin or drill/tap holes in remaining shaft and the replacement shaft to fit the knob.

[bwheat]

Are you sure? I've had success more often than not popping these off and snapping them back on again. You may have to file the crimped metal a bit, but usually they still stay put when reassembled.

It might be possible, I know a lot of these use nylon which is somewhat flexible. Mine has some what appears to be very fragile clear plastic instead. I will mess with it a little more and see if I can get it loose.

[bwheat]

Following g1's lead, I dug out one of my broken shaft pots, pried off the cover, found on this pot the shaft/rotor assembly came free from the bushing casting and the resistance wafer. Sometimes that isn't the case, as there can be a step in the knob-end of the shaft that's larger than the shaft dia passing thru the bushing. I don't think that's the case on your broken pot.

Anyway, I took a series of photos, beginning with cutting at the flared shaft end that protrudes thru the nylon rotor assembly.

[ATTACH=CONFIG]50567[/ATTACH] [ATTACH=CONFIG]50568[/ATTACH] [ATTACH=CONFIG]50569[/ATTACH] [ATTACH=CONFIG]50570[/ATTACH] [ATTACH=CONFIG]50571[/ATTACH] [ATTACH=CONFIG]50572[/ATTACH] [ATTACH=CONFIG]50573[/ATTACH]

If you have any other broken pots, I'd suggest practicing the procedure before committing to the one that counts. After I began prying the nylon rotor up, pivoting off of my small machinist vise with a Wiha bladed screwdriver, it finally began lifting up. During the filing process, I slipped off the top of the rotor, and dinged the multiple finger wipers of the pot, so those parts are very fragile and easily broken, so beware.

The flatted rotor end of the shaft is very tight fitting, so g1 is quite correct in that they would stay put after reassembly. Sorry for the out-of-focus shot looking sideways at the shaft-rotor assembly...camera focused on the nearest surface of the vise, not the shaft/rotor.

But anyways, he's right......with care, you CAN disassemble these. Now, coming up with the replacement shaft??? Might be that further machining is needed, with grinding the broken end flat/perpendicular to the shaft, marking & center-punching the center of the shaft so you could pin or drill/tap holes in remaining shaft and the replacement shaft to fit the knob.

Mine is slightly different than that. It has what appears to be a very brittle clear plastic, but where the shaft goes thru it is pressed at the end to where it is squished out and makes a round taper on the end of the shaft. It seems like they inserted the shaft into the plastic when it was still warm enough to be flexible and then pressed the end of the shaft to taper it. So it's basically a cone shape of metal inside a cone shape hole. I have gotten the type in the picture apart and back together in the past back when the Internet was still in the early stages and your options were going to a guitar store, radio shack or musicians friend who might not have what you need so you actually had to fix things, haha. I remember having an old series 10 Jackson style guitar way back in the day and it had a size of pot I couldn't find locally. It wasn't physically broken like this one, but the little finger contacts were broken off and missing. I ended up taking apart a few old ones and found one with a similar design and used the rotor and attached it to the shaft from my original pot and put it back together. Can't say a little epoxy wasn't involved, lol. It worked though. That's part of my problem now, I used to have quite a few of these laying around, but got on a decluttering kick a while back and threw a bunch of stuff away in hopes that I would always be able to buy a new one in today's everything you want it available in mass quantities days.

[bwheat]

https://images.reverb.com/image/uplo...9ze6tq5p7r.jpg Really considering something like this, it has a larger diameter bushing, but it can be made to fit. And is 3mm to long, but a few washers to shim it a bit would fix that. It looks possible to cut the eyelets off, fold them around and fit right into the spots into the board. The shaft is .3mm larger but I could run a 1/4 bit thru the bore of the knob. Seems like a lot left work than trying to repair the old pot.

[nevetslab]

https://images.reverb.com/image/uplo...9ze6tq5p7r.jpg Really considering something like this, it has a larger diameter bushing, but it can be made to fit. And is 3mm to long, but a few washers to shim it a bit would fix that. It looks possible to cut the eyelets off, fold them around and fit right into the spots into the board. The shaft is .3mm larger but I could run a 1/4 bit thru the bore of the knob. Seems like a lot left work than trying to repair the old pot.

Have you contacted Reverb to see what the pot value/taper is? Those look like you could adapt them easily, if the value/taper is ok.

[bwheat]

Going to contact the guy today actually. The ad says reverse audio taper, 500k. I don't really want a reverse pot in there, but they might be able to give me an idea where they got them if they don't have the non reverse.

[bwheat]

Still never heard back from the seller of that item I posted after sending multiple messages. I did fine something else that will fit, but it is an A500k instead of a b500k. I assume that would work perfectly fine for this application? https://www.amazon.com/2-pack-500KOh...10&ref=sr_1_10

[bwheat]

Last one was too short after talking with the seller, but I believe I have found the one after lots and lots of searching. About 3mm too long, but a couple washers will fix that right up. Even long enough leads to cut the eyelet off, bend and push thru the holes in the board for a direct mount. https://www.ebay.com/itm/Bourns-Pro-...N_UF1LYY4Et-Vw

[bwheat]

Well, still too short according to seller. The whole shaft is shown as 19mm not the threaded portion. Pictures are awfully deceiving.

[bwheat]

Ended up getting ahold of the one on reverb.com. Had to space it out 3 mm as it was a little longer, and dremel out the hole in the pcb a hair, but it worked out well.