On Nov 2, 2025, at 11:54, Wayne S <wayne.sudol(a)hotmail.com> wrote: Try cleaning it as Paul saysand se if that works. Carbon pots get a groove worn into them after time and the wiper ends up making intermittent contact. Usually you can take them apart and visually check. It’s possible that just the wiper is worn. Also possible the carbon element is cracked. It all cases it’s just easier to replace the control. Sent from my iPhone > On Nov 2, 2025, at 11:48, Paul Koning via cctalk <cctalk(a)classiccmp.org> wrote: > >  > >>> On Nov 2, 2025, at 2:15 PM, Rob Jarratt via cctalk <cctalk(a)classiccmp.org> wrote: >> >> I have the contrast control on the monitor of my Olivetti M24 which has >> become unreliable, you only need to touch it and the display will disappear >> completely. It doesn't look too hard to replace the rotary potentiometer, >> but I was wondering if there is any way to "repair" it to keep the original >> part. It looks like this: >> https://1drv.ms/i/c/fc758a5a91b91301/ESPGlbvW5wxGpXPC5kXfzVMBTUUW96GThzDMqZ_ >> i8jq7tA?e=Ehmo1T > > I have a spray can of cleaner from Radio Shack that's designed to do this. I used it a year or two ago to clean the pot on my toaster (the toast darkness control). The can says it is "Tuner control cleaner & lubricant, part number 64-4315. The ingredients list mentions 1,1,1,2-tetrafluoroethane, cyclomethicone, and mineral oil. I suspect it's considered non-PC nowadays, but I'm keeping it. > > It may be that turning the pot through its range a bunch of times will rub off crud. > > paul >

I should also mention that if it’s a wirewound pot, the wire where the wiper sits can get pitted and grooved. If you have a good magnifying glass and patience, you can use just a little of the paint-on silver conductor stuff that was used to fix car antennas that were embedded in windshields and fill in the groove. It’s very exacting work though because you can easily get some on more than one wire causing a short. Sent from my iPhone > On Nov 2, 2025, at 11:54, Wayne S <wayne.sudol(a)hotmail.com> wrote: > > Try cleaning it as Paul saysand se if that works. > > Carbon pots get a groove worn into them after time and the wiper ends up making intermittent contact. > Usually you can take them apart and visually check. > It’s possible that just the wiper is worn. > Also possible the carbon element is cracked. > It all cases it’s just easier to replace the control. > > Sent from my iPhone > >> On Nov 2, 2025, at 11:48, Paul Koning via cctalk <cctalk(a)classiccmp.org> wrote: >> >>  >> >>>> On Nov 2, 2025, at 2:15 PM, Rob Jarratt via cctalk <cctalk(a)classiccmp.org> wrote: >>> >>> I have the contrast control on the monitor of my Olivetti M24 which has >>> become unreliable, you only need to touch it and the display will disappear >>> completely. It doesn't look too hard to replace the rotary potentiometer, >>> but I was wondering if there is any way to "repair" it to keep the original >>> part. It looks like this: >>> https://1drv.ms/i/c/fc758a5a91b91301/ESPGlbvW5wxGpXPC5kXfzVMBTUUW96GThzDMqZ_ >>> i8jq7tA?e=Ehmo1T >> >> I have a spray can of cleaner from Radio Shack that's designed to do this. I used it a year or two ago to clean the pot on my toaster (the toast darkness control). The can says it is "Tuner control cleaner & lubricant, part number 64-4315. The ingredients list mentions 1,1,1,2-tetrafluoroethane, cyclomethicone, and mineral oil. I suspect it's considered non-PC nowadays, but I'm keeping it. >> >> It may be that turning the pot through its range a bunch of times will rub off crud. >> >> paul >>

On Nov 3, 2025, at 18:03, Doc Shipley via cctalk <cctalk(a)classiccmp.org> wrote: On 11/2/25 16:15, Christopher Zach via cctalk wrote: This may be a dumb question, but would it be possible to add a low-value resistor to the circuit and change the tuned position of the pot? Doc