I picked-up an JV-90 last week for little money. It’s a bit dirty and a handfull of keys don’t work. I wanted a 76 keys synth again so I’m going to fix this one up 🙂
- Polyphony – 28 voices (expandable to 56)
- Oscillators – Digital Acoustic simulation via 4MB (expandable to 14MB) of ROM
- Arpeg/Seq – None
- Filter – Digital filters
- Effects – 2 effects units with chorus, reverb and delay
- Memory – 256 Patches (can expand to about 600); 64 Performances
- Keyboard – 76 non-weighted keys (responds to velocity and aftertouch)
- Control – MIDI (8- to 16-parts)
- Date Produced – 1993
At home I’ve tested the synth before I took it apart. Indeed a few keys didn’t work but what concerned me was that when I played a patch it sounded like a sustainpedal was attached and someone was pressing down on it. Even when you switched patches you would still hear the previous patch.. After a factory reset of the synth this problem seems to have disappeared. Hope it stays that way 🙂
I’ve put the synth in testmode and discovered that about 20 buttons don’t work very well. I’ll be replacing a lot of tact switches on this one. The aftertouch actually works but you have to put quite some pressure on the keys. I’m going to find a solution for this to. It usually involves soldering a resistor on a circuitboard somewhere.
Taking it apart:
First cleaned the keys. The JV-90 doesn’t have a semi-weighted keybed like the JV-80 and JV-1000. This is a shame because semi-weighted keys play better (my opinion). On the other hand; it saves me hours of waiting for this freakin’ red glue to dissolve in caustic soda 😉
Dirty keys soaking in the kitchensink:
While letting them soak for a while I cleaned the metal frame of the keybed which was pretty disgusting:
Placing the contacts and contactboards underneath the metal frame is brilliant. This prevents a lot of dust and dirt from reaching the contacts. The rubber contacts and circuitboard where pretty clean on this JV-90. It’s just the metal frame that is dirty. Check these pictures of my D-5 and JD-800 projects below to see what the contactboards look like after a while (decades) when placed on top of the metal frame..
It also makes servicing the instrument easier as well. You don’t have to remove the keybed from the synth (not a very easy job with a JV-80 / JV-90) and you don’t even have to remove the keys if you just want to clean or replace a contactstrip. Just removing the bottom plate of the synth gives you instant access to these parts.
I removed the contactboards and cleaned the rubber contactstrips and the boards:
And reassembling again:
I’m pretty sure all the keys will work again now. Only about 5 were not working before but I won’t know until I reinstall the keybed in the synth. Before I do that I have to remove all the circuitboards to replace these tact switches..
Will update soon!
Update september 2 2015:
The JV-90 has +- 64 buttons and about 20 of them don’t work (very well). I have 30 replacement tact switches in stock. Hmm.. replace half and risk having to take it apart in the foreseeable future to replace more? No. I’ve decided to replace them all. The shop I usually order these tact switches from charges 0,15 euros a piece. Not very expensive but I’ve decided to order 200 from Ebay at 0,0325 euros each. It’ll probably take a week or two before they arrive though..
In the meantime I’m looking for a Roland JV-1000 synthesizer. They look very cool and I’ve always wanted one. There’s a project one I’m going to try and buy from someone. Hope that works out 🙂
Update september 15 2015:
The new tact switches haven’t arrived yet but since I had 30 I figured I just start with the job anyway.
Taking the JV-90 apart:
As you can see in the pictures I’ve removed the switchboards and they are dirty 🙂
I desoldered all the tact switches and cleaned the PCB’s. You can see that there is a lot of dried up residue on the boards. Probably something like WD-40.
After cleaning and replacing some switches:
I cleaned this with alcohol and the boards look nice and clean again. I replaced all the switches on one board. Have to wait for more switches to arrive to finish this job.
Some more pictures of the dirty insides of the synth:
Update december 3rd 2015:
I’ve replaced all the tact switches and they all work fine again. I’ve put the synth back together and tested the keys. Some still didn’t work. Took it apart and cleaned the contacts underneath those keys again (several times) and now they all work.
Still 2 problems:
The volume slider works very badly. The synth only outputs sound on the right channel at 99% of the travel of the slider. There is only one tiny spot where I have stereo sound. I have desoldered the slider and taken it apart, cleaned it but it was clear the the slider was worn out in the inside. Cleaned it anyway and put it back together. Soldered it back into the synth and now it works even worse :’) I’ve contacted Roland to order a new one but they cannot supply them anymore.. I’ve ordered these before a year ago so that’s a bummer.
The other issue: the sustain problem. Sometimes when you switch it on it sounds like there is a sustainpedal attached and you’re pressing down on it. Very weird. If I press the panic button combo it goes away (and stays away) but it can come back the next time you switch it on.. not really a disaster but it makes me wonder what to do with this synth. Part it out or sell it as ‘functional with minor issues’ 🙂
Yesterday new parts arrived from www.synth-parts.com.
Finally I have the new volume potentiometer. I soldered it in place and put the whole thing back together.
The volume control works fine again now! 🙂
Still two minor problems: one key isn’t always velocity sensitive and when you power it up it still has the sustain problem.
I’m going to see if painting the contacts for the one key that doesn’t work well with conductive silver paint will fix it. I’ve read that people use this stuff for this application and that it works fine.. I have this paint so I thought I’ll give it a try.
The sustain thing is really weird though.. it’s not really a problem but it isn’t supposed to do this 🙂 all the notes you play will continue to sound untill it runs out of polyphony. Pressing the panic buttons solves the problem immediatly. It stays away to for the rest of the session..
Update january 16th 2016:
I ended up painting 3 or 4 contacts with the silver paint for everything to work fine again. Still everytime I powered it up it had this weird sustain problem. Until I connected a sustain pedal to the HOLD port on the back at some point. That seems to have fixed it 😀 probably dust or dirt in that port.. works fine now.