Hmm so I've had #1 apart. It all looked original, you could tell by the screw sound when I undid the boards and th general tightness of the wiring compared to my other one (which has had slider repairs in the past). And yet, for some reason I've found 'Jumper 5' on the synth board has been 'cut' and bent over slightly so it doesn't connect!
I'm wondering if this could ever happen by itself (heating up?) and if not why would someone cut it, unless they had previously modded it? but I see zero signs of any mod work and it was that dusty inside behind the controls etc that it certainly hadn't been cleaned out before either.
On my other 101 J5 is connected of course. gonna look at the schematics to see what J5 does/where it leads before I solder it back up but any thoughts in the meantime would be welcome.
Also what is the best way to test the sliders with a multimeter, I seem to be getting erratic readings (like the covering they use after assembly on the PCB is stopping a good reading, should I scrape this clear first) and which pins are best to test on the slider and what resistance am I looking for on FREQ, PWM and PWM VOL? at it's lowest and highest positions - Thanks!
edit > also on #2 there is a white jumper wire on the top of the synth board (I've seen this in other pics of other 101s but on #1 there is none but there are 2 resistors on the back?) #2 is an earlier serial number so could this explain these differences? DId they change from resitors (on the trace side) to the white wire on the component side? If not then perhaps those resistors were also part of a mod.. must google for 101 innards to check this
Oh sorry for all the qs but other than a mild soapy water solution and a soft sponge / tissue is there any better way to get a grey 101 back to grey instead of 'off grey/smoke tinged'? I've cleaned them both up and they look better but still not as grey as some I've seen, not sure you can get it completely new looking but any tips?
---------- edit / slider findings ----------
So I tested the lot using the 'obvious' testing points of the sliders using 200k scale. I tested them fully open and closed: from left to right (starting with lfo ending on release)
open: 0.3 closed: 55
open: 0.3 closed: 50
open: 1 closed: 1 (PULSE WIDTH: Dead/slider contacts not touching)
open: 0.3 closed: 49
open: 0.3 closed: 20
open: 0.0 closed: 86
open: 0.3 closed: 59
open: 1 closed: 1 (FREQ: Dead/slider contacts not touching)
open: 0.3 closed: 40
open: 0.3 closed: 40
open: 0.3 closed: 37
open: 0.0 closed: 80
open: 1 closed: 1
open: 1 closed: 1
open: 0.3 closed: 50
open: 1 closed: 1
So from this test it would seem those 2 sliders (on unit #1) are defintely acting up. It's either the broken tracks inside or the contacts not touching (can try bending them down again), as PW slider was doing 'something' when cleaned it may just be the contacts need a bend.
What is puzzling me is the envelope readings, showing 3 'dead sliders' yet the envs were working fine before I dismantled it so I won't know if they are really dead until I assemble it again I guess.
Also some of those readings are way different (esp for closed) Is that just the various types (A/B and that other one I see in the schematics) or does this mean they are not operating in correct tolerance and should be replaced to get the 'proper sound' back?
And some good news (I think) is I have a roland 'made in japan' 100k B slider from a JX-3P that I replaced the slider on with a broken stem. I hope it's the same thing as i'll be able to test it at least. (after replacing stem from 101)
edit > sorry for this mega post but, I've just dismantled the 2 dead sliders and tested the tracks, looks like they are in good condition aside from somewhere the single connected side (the 0k signal) there is a lack of continuity in the track, so this may be a good candidate for the conductive paint trick mentioned above as the other side is testing fine (0 - 100k on the track). Also both spring connects had some greenish oxidisation which i cleaned off and bent the connects (and the pushy brassy colour thing) down a bit for better contact. I reckon if I can just add that paint so the track has continuity it will be fixed, resolder them in and job done I hope. I can see why it would break there, it's where those two spiny/sharp contacts sit for 30 years in one position being pressed onto it.
I need to get some key contact paint for one of my polysix also so I should be ok to use that stuff on these?
So