Roland PG-200 replacement pots

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gslug
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Roland PG-200 replacement pots

Post by gslug » Tue Sep 10, 2019 6:11 pm

Anyone know of a source of replacement pots for this? The originals are an unusual design - 16mm, vertical PCB mount, but with the track on the bottom and the bushing crimped to the top of the metal shell. There is a seperate bracket, held in place by the crimping of the case to the base. The only other place I've seen them is in the Jupiter 6.

I've looked for alternative snap in 16mm pots, and they just don't seem to exist any more!
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Starspawn
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Post by Starspawn » Wed Sep 11, 2019 12:44 pm

I was planning to try the P160KN2 series, knurled, 100k and whatever height is needed.
Seems like legs will bend in position. No body legs, but otherwise a fit.

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gslug
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Post by gslug » Wed Sep 11, 2019 7:57 pm

Thanks. I've found some of the original type on vintage synth shop, but they are rather expensive. I ordered one to see if it's any good and if it has I part number that I can put into Google should I need some more. My newly acquired PG-200 has one broken pot (bushing popped out of case), but a few others are slightly bent, and may no longer make proper contact - I can't test yet as one of the electrolytics had blown it's bottom and so am awaiting replacement caps too.

If I do manage to find a reasonably cheap supply, I'll post it on here. If not, and it turns out that I need more than one, I'll go with your suggestion. I was concerned about wobble with the lack of the base legs, but I guess it would be possible to wrap a thick wire around the bushing and solder it in the holes, ala x0xb0x encoder.
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gslug
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Post by gslug » Tue Oct 22, 2019 6:14 pm

As predicted, the rather expensive pot I brought wasn't an exact match - the shaft is shorter, but it does the job.

Turns out there was more wrong with my PG-200 than just the pot. The comparator was too hot to touch and none of the pots worked. Replaced it and found only some of the pots worked. Replaced the 4051s and all of the pots worked. Briefly.... No idea what's going on, but it seems to kill 4051s. On the back burner for now!
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Starspawn
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Post by Starspawn » Wed Oct 23, 2019 11:40 am

I changed all mine for the ones I linked. Shorter and have to bent legs and add something to brace, but worked fine. My main problem though, was the C945 transistors, changed them for 3904 (with one leg passed to other side and backwards) and it all started behaving.

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gslug
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Post by gslug » Wed Oct 23, 2019 5:52 pm

Thanks. I don't think those transistors are at fault in my case, as they are related to the manual and write buttons, both of which work fine. I'm suspecting some of the other pots are making intermittent contact, causing floating inputs to the 4051s, leading to possible oscillation and death... I'll probably change all the pots at some point and see if that fixes it.
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