With only a few more days off from work I decided to continue working on the potmeters today. I gathered all potmeters from the string ensemble and set to work.
The previous repair using loctite didn’t work out, so I removed the sliders, cleaned away the loctite and tried again using super glue, but again it gave even before reassembling the potmeters. So I decided to try a method seen on a previously mentioned blog by drilling holes and suspending the sliders from there.
As I had no rigid copper wire to use I turned to toothpicks. I cut them to length, put a bit of glue on the tip and wedged them in. This time the repair seems solid, however I doubt I’d be able to do it again should the need arise in the future. A replacement potmeter is the more likely way to go then.
The second problem with the potmeters was a missing contactpoint. These little buggers pop out soonest you disassemble the potmeter and it’s these times I wish I had a cat (as someone on an other restoration blog pointed out, cats are capable of instantly finding whatever you shot to wherever). I initially glued the graphite contactpoints back however glue got inbetween the point and the slider, thereby breaking continuity. I had to redo it, this time simply wedging them back in. Seeing the conical shape I suspect this is how they should be mounted!
If you look closely in the image above you’ll see my solution for the missing contactpoint. I disassembled a relay I bought new and simply soldered the contactpoint back onto the slider. This has changed the characteristics of the potmeter slightly, however only by several tens of Ohms over a total of 10kOhm. This I can live with…
I reassembled the potmeters using again a trick I learned from an other blog (why invent gun powder again) and with the insides fully cleaned using an impressive array of chemicals the potmeters slide like when they were new, well…almost 
On the left you’ll see the slider of one of the stereo potmeters. As posted before the copper contactors were broken off, but mending it with loctite seems to have done the job in fixing that.
While he went to work on dirty potmeters for the string ensemble I myself got to work on remounting and cabling the cardbasket. The speakers went back in, the accelerator (aka volumepedal) was adjusted and put back, so as the transformer. Unfortunately, the latter decided to throw me a tantrum. One fuseholder broke during cleaning and will need replacing. While soldering back the wires, neatly covering them all with heatshrink tube, some of the PCB copper traces came off and will need repairing. No big deal but another job added to the list.
The thing to keep in mind is that, first of all, these potmeters are NOT available anymore, meaning any damage needs fixing. Also, with them having capacitors I’m guessing the potmeters aren’t simply just that, but adjustable RC-networks. The copper contactholders attached to the plastic sliders are a PAIN in the arse to put back, especially the stereo ones.
It looks more complicated than it really is, but taking it apart for cleaning can seem daunting. I decided to snap a few photos and get to it. It came back together fine, but I’m not sure still it’s switching properly as inserting the jack doesn’t break the 1st contact right off the centre. I’ll have to check the schematics on that one. Otherwise the cleaning went fine and the jack is now where it should be, nice and clean.
Loading ...
I am…., kneedeep in an organ!
Here you can see the empty casing with the supporting keyboard panel still in place. I removed it later on to create space for turning thru the staircases and looking back that was a very good and most of all, badly needed move on my behalf.