From Andrew Horton Sent Tue, Jul 17th 2018, 14:36
From Andrew Horton Sent Tue, Jul 17th 2018, 14:36
This is brilliant work. Someone, probably Florian, talked a while back about adapting this to the System 100 because of the fact that they don't have to be mounted on the PCB. I hope that can be done because I have two on my 100 that are going bonkers. On Tue, Jul 17, 2018 at 10:26 AM Kerry Bradley <xxxxxxxxxxxx@xxxxxxxxx.xxx> wrote: > > Fantastic, great work, Kenny - this is one of the best reasons I subscribe to AH. > > My rescued JP4 may need these someday - it's great to have this info & experience documented. > > > -----Original Message----- > >From: Kenny Balys <xxxxx@xxxxxxxx.xxx> > >Sent: Jul 17, 2018 2:01 AM > >To: analogue <xxxxxxxx@xxxxxxxxx.xxx> > >Subject: [AH] Jupiter-4 50K Frankenslider Install Notes + Photos (public domain) > > > > > >Jupiter-4 Frankenslider Install Notes > >-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > >17.07.2018 kennyb * Public Domain * > > > >This is a little bit of commentary to support the > >photos included here afterwards. > > > >These words and associated photos are public domain and can > >be used for any purpose whatsoever in perpetuity. > > > >Acknowledgements: > >-=-=-=-=-=-=-=-=- > >All of this is possible because of a description, BOM and board > >design from "Homemade Polysynth". This is the link to his > >description: > > > >http://polysynth.tumblr.com/post/84043081480/replacing-roland-jupiter-4-slider-potentiometer > > > >No one, in their right mind, would want Frankensliders in their JP4. > >Unfortunately, there are no replacement 50K sliders available for > >the Roland Jupiter-4 and when they fail there is nothing else > >at the present time. > > > >There are seventeen 50K sliders on the JP4. The other 3 are absolutely > >irreplaceable right now. The irreplaceable ones are ARP RATE, > >LFO BEND and DELAY TIME. > > > >My Jupiter-4 had some greasy, oily goop in all of the right hand sliders. > >They started to fail last year and then quickly got worse and worse. > >By the end, there were dead zones in the filter cut off and flaky > >behaviour with the envelopes. Some previous owner had sprayed some crap > >into the machine. > > > >So I needed to replace all the of 17 50K sliders. I saw Homemade Polysynth's > >plan and board designs to implement Bourns PTA3043-2010CIB503 50K sliders > >using 2 daughter boards, pins and spacers. > > > >I ordered everything from OSH Park board fab, DigiKey and Mouser. > >See the "Homemade Polysynth" webpage for ordering data. > > > >The photos should be self explanatory. This method works. You will have > >a working Jupiter-4 with silky smooth sliders again after this. Pay heed > >to the two issues listed here. > > > >Start by building the 17 sliders. Make sure that you get the spacers > >in the board sandwich as flush as possible. This is not easy. Take your time. > > > >After dismantling the JP4 and replacing the sliders there remain 2 issues > >before you will have a working synth again. > > > >First Issue: Major > >-=-=-=-=-=-=-=--=- > > > >- the outer pins of the Roland 50K sliders are connected. These self > >made stacked ones are not; they make the 2 connections on the bottom > > and 1 on the top. > >The upper most is N/C. This is totally fine for 16 of the positions > >but the VCO LFO MOD slider is connected via the top, not bottom. > >This problem drove me nuts for hours! When I found it, it was so > >obvious. > >(upper means the up direction when facing the opened JP4, > > looking at the back of the slider boards) > > > >Solution: jumper the top pin to the bottom pin > > > >Second Issue: Minor > >-=-=-=-=-=-=-=-=- > > > >- the stacking of the potentiometer is meant to level the shoulders > >of the knob shaft with the originals, this is great as visually, from > >the outside, the slider caps are all level. > >The problem is that it is near impossible to get the exact 2.53 mm > >spacing between boards as solder tends to fatten the pins and push the > >spacers out a little bit. Also, the tolerances are such that the > >sliders sit a little bit higher than they should and bash metal. > >It needs a tiny bit of a spacer to avoid banana'ing the boards when > >they are fastened again. > > > >Solution: I used self adhesive cork about 1.5mm thick along the entire > >fastening rail. This gives the amount of lift needed. > > > >Conclusion: > >-=-=-=-=-=- > > > >My Jupiter-4 works perfectly now. The sliders had been getting worse for > >a while. There was nothing else I could do but this. Now I can play again. > >The Bourns sliders are smooth and appropriate to the JP4. > >I am very grateful to Mr Homemade Polysynth. > > > >Download link for photos and this text: > >-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > >http://www.beatkamp.com/downloads/JP4_Frankensliders.zip