This week I found a Roland JX-8P in great cosmetic condition. I’ve always been interested in this synth because I’ve heard it’s been used on the a lot those Italo Disco records for strings and pads. After testing it out and playing through the presets and internal patches it’s not all that bad of a synth. I feel I need to do some programming a bit and scour the web for some better patches, but I know with the right ones, the Roland JX-8P is going to sound great.
one problem I did find so far with my Roland JX-8P is the occurrence of a stuck note that happens completely at random. It also happens on different notes and not the same one. I’ve pretty much ruled out the idea that this is a dirty or problematic key due to the fact that it’s all completely random. ( Perhaps not so if some sort of diagnostic test could be run which I’m not aware of yet. I’m currently checking out the service manual ). I did find while search for similar problems a member on Gearslutz who reported the same issue. He fixed it by replacing a NEC D8253C-5 divider chip. I decided to investigate more about this.
I opened up the Roland JX-8P and found four divider chips labeled NEC D8253C-2 and NOT NEC D8253C-5. Does the “2” and “5” make a difference? I’m not sure, but to be on the safe side I decided to order a set of NEC D8253C-2 chips off Ebay which are readily available for around $4.00 each. I also noticed that these chips appeared to be soldered. This is not a big problem, but it does mean a short soldering job is in store. Am I sure this will take care of the problem? No, but it’s a start and with one success story it’s as good a solution as any at the moment.
Even with this sticky note problem, the Roland JX-8P is very playable and I found that if I could decipher the exact note right away, I could simply hit that note and it would go away. The stuck note is also mild and not “in your ear” blaring away! Hitting the note again did not make any sound rather it simply cut off the stuck note. The stuck note also happens very infrequently but enough to probably happen once or maybe twice during a song. For recording purposes, the stuck note is a non issue really. For live purposes this could be a problem if one is not paying attention. So I’m not completely worried about it unless it gets worse. For the price I paid, I expected a major issue. So far, I would say the NEC D8253C-2 chip problem is minor although I would love to find out which chip is the culprit rather than pulling all four. That’s 24 pins of soldering for each chip. I could test after each one and hope for the best and get lucky. We’ll see.
Currently I have yet to get accepted to the Yahoo JX-8P groups which often has discussions about these sort of issues. The good news is that it’s not a huge problem and most likely fixable with NEC D8253C-2 chips. After my Roland Juno 106 experiences, I really don’t want to be bogged down again with chip issues again….laugh.
I’m enjoying the Roland JX-8P. It was a nice find no doubt about it. I use the Midi Designer iPad app as a PG-800 controller. There is a brilliant Roland JX-8P editor in Midi Designer and it works awesome.
Here’s a demo on Youtube of the Roland JX-8P in action from Jexus. Great stuff!
Jim Atwood in Japan 
I just discovered a weak tact switch on the Roland JX-8P internal button. I ordered some extra tact switches here in case anyone needs them: http://bustedgear.com/part_switch_tactile.html#SWTAM4
You can also use these very same tact swtiches for the Korg DW8000, Korg Poly-61 and Yamaha DX-7 of which all have problems from time to time with their membrane switches. I bought a 10 pack and I know it will serve me well.
Here’s another bit of important info:
Press the PIANO 2 and 3 tone buttons while turning the JX-8P on to enter test mode. The voice being played is indicated by the Solo, Unison, Poly, Volume, Brilliance, and Vibrato LEDs corresponding to voices A, B, C, D, E, F respectively.
Hi Jim!
Don’t forget to use sockets for the new chips – but I am sure you will do…
Did you already check if the stuck notes don’t come from bad midi data? Try another MIDI note source and maybe shorter MIDI cable… Maybe the optocoupler inside the synth is too slow and if your midi signal goes via some midi routing devices the signal quality could be disturbed… At that time some synths had this problem…
Ciao
Peter
Hello Peter! Thanks for the tip about the sockets. I just put in an order on Ebay for a bunch and will no doubt use them. I have four IC chips to possibly replace and will definitely be able to socket them.
This evening I actually opened up and removed the main CPU board of the JX-8P. It looked good, but the button membrane board above it looked to be tampered with which was interesting. I had a problem with the internal patch select button not responding. I thought i would check the tactile switch and to my surprise three of the wire connectors to the membrane board were practically out of their sockets. There also was a missing screw. I clean up the problematic membrane tact switch and after putting it all together, I was successfully able to access the internal patch bank thank goodness! Now I can access, transfer and save patches.
The only remaining little problem is the stuck notes which really isn’t happening all that often. In fact I’m wondering if it might be the “note stealing” problem that is common on the JX-8P due to the low polyphony. It also seems to happen on patches with longer release times which is interesting. I also notice if I place more slowly like one would when playing strings, it doesn’t happen either. If I’m playing a brass synth sound very quickly with a long release time, it seems to trip things up so it seems.
In any event, I’ll have a couple of weeks to research the problem before my replacement IC chips and sockets arrive. I may not have to use them if I’m lucky.
with the slower envelopes, note stealing, and overall different sound character of the JX-8P, I find it really different than my Juno series synths. Indeed the pads and strings are really nice. They sound as if they are floating ever slow slightly which is very pleasant to my ears.
Thanks very much lately for the excellent info and comments. I greatly appreciate the support. Hope all is well with you.
Jim
I found the problem with my Roland JX-8P!
First, I midi’d up an external controller ( Roland A90EX ) and played for about an hour flipping through all the patches with absolutely NO issues whatsoever. This meant that the sound module inside was working 100% and that likely my problem had nothing to do with the voice chips or divider IC chips. All clear! With the Juno 106 for example, if you midi’d up a controller with the voice chip problem, problems would still occur because obviously the voice chips affected the sound module regardless of what keys you were playing.
So I started to continue my research using the on board keybed. I then noticed that the stuck notes got worse as I raised the after touch slider. If I cranked it all the way up, I was getting about 7-10 stuck notes. The stuck notes also appeared to be occurring on the same keys although when they got stuck was random. When I brought the After touch back down, there maybe were only 1 or 2 stuck notes. In addition, these notes would only last a few seconds and then would get cut off. So the release time of the after touch was greatly reduce when the after touch was at zero or close to it. ( If that makes sense. Not sure ).
Thus I believe I have an after touch problem which is from what I hear the biggest issue with the Roland JX-8P. This means I’ll have to open it up and clean the after touch strip and check the key contacts. This likely should eliminate my issue. Note that with the after touch off I get no stuck notes or at least it’s cut off quickly. I’m not sure exactly what’s going on, but the problem is almost gone.
What was confusing about this matter was that the symptoms were very similar to that of the Juno 106 without the static of course. Notes would sustain indefinitely and would then not play again because they were already stuck or would skip. These are classic symptoms of Juno 106 voice chip issues. It was hooking up an external midi controller that nullified this as a problem with the JX-8P.
Now I’m off to fix the after touch. Whew! Thank goodness the issue is not as serious as I first thought.
Jim
UPDATE: My previous update didn’t quite fix the problem.
Everything works great except I get stuck notes when I hit several keys, primarily the black ones. The notes just sustain and when I attempt to hit them again they don’t don’t sound obviously because they are sustaining. When I attach a keyboard controller ( A90EX ), I can play without any issue at all. The JX-8P is perfect!! Thus no problems when using a controller keyboard.
I did remove the keybed and gave it a good cleaning. Aftertouch works very well and everything is squeaky clean. The sustain note problem existed before and after the key cleaning, although it does seem the problematic keys have shifted from the white to black a little bit. It’s kind of random.
Since the keyboard controller works, I suspect I am having a problem with the key contacts, wiring, or something with the JX-8P original keybed. I just can’t figure out what it may be. I don’t think there is a chip problem because then the controller wouldn’t work either via midi. Under the keys there are three metal (copper?) prongs that have contacts on them. When you press on the key it touches and then triggers notes on and off. I checked these and they all look pretty much right on. I could see if they were bent it might be a problem, but there isn’t any such problem. I also cleaned the contacts on the metal pieces.
I hear lots of people have had issues with stuck notes and keys and the Roland JX-8P, but after a few days of searching the web, I haven’t been able to find any written info about it. There is a JX Yahoo Group but it seems the moderator doesn’t accept new members.
I otherwise have a mint working JX-8P, but only via the midi controller. Looking on the bright side, at least that works, but it sure makes for a large sound module…laugh.
Ok, I “may” have found the problem. If any JX-8P users out there could confirm this, that would be great.
I basically discovered too things which lend me to believe that these JX-8P keys are EXTREMELY sensitive.
1. If one key does not work correctly it WILL set off a chain reaction to other keys. I am not sure the pattern for this but I’ll have to check the service manual to see. To test, I took one key and purposely bent the copper metal beneath the key out of shape. That key did not work and so did a few others nearby. So these keys are all interconnected in some way.
2. I still have no idea what the “correct” way is, but the three copper metals strips have to be bent in a pretty strict fashion for the key to trigger properly. It’s very hard to explain in this post or even in pictures, but after spending an hour getting a feel for how the strips should be I think I have it down now. I found tweezers to work very well at bending the strips.
To test the keys I would plugin the JX-8P and play the keys. I would then mark them with tape and while the keyboard was turned off bend the copper strips underneath. I must admit it’s a bit trial and error, but I FINALLY got all keys working.
The final problem is playing this with confidence without anticipating a key to sustain or not work. Fortunately pressing hard on the keys will not bend the contacts underneath.
So anyone with stuck notes on the JX-8P I recommend the following:
1. Test with midi to make sure it’s a key problem and not a chip problem. If all keys work great for about 5-10 minutes, it’s a key problem. ( Note we’re not testing aftertouch, rather just the key contacts ).
2. If keys sustain only with the JX-8P keyboard, you’re then going to have to clean, bend, straighten the copper key contacts until you get a signal.
Without a doubt, the Roland JX-8P is the crappiest keyboard I’ve had to work on. ( Playing is fine, but cleaning is one of the worst. ) It’s definitely a precision tuned key bed. Those with a fully working JX-8P, I can’t recommend enough to NOT touch those copper metal strips in any way shape or form. Be very careful when removing the keybed and keys.
….laugh… As long this works now I will hopefully never have to remove the keys or key bed again.
Hope this helps a few out there. Thanks!
I got this from some forum, but I can’t remember were. I may do this.
I finally got the Behringer BCR-2000 to work with the Roland JX-8P. I had problems initially because after updating to the latest BCR-2000 firmware it killed the USB connection ability. So, I had to update the firmware again via midi using MIDIOX. Then I as able to connect my MacBook Air to the BCR2000 and transfer the Roland JX-8P preset to the Controller. After that I put the BCR2000 into S1 mode, hooked up my midi cable sot the Roland JX-8P and was having fun modifying patches. The Behringer BCR2000 works very well with the JX-8P as does the MIDI DESIGNER app if you also wish to use the iPad.
I had this on my old 8P. It really is as simple as ensuring your upper copper contacts are de-oxidised! Ie SUPER clean and conductive.. even using a bit of fine sand paper to remove 30 years of build up.
If the middle prong is never seen to touch the upper ‘off’ leave contac then your note will sustain. That would always be my first attack on an a dodgy JX-8P keybed with leaf contacts (rather than rubber cups).
Secondly would the gate array chip (if it has one can’t recall but the alpha junos 2 and these often die and leave stuck notes or no notes).
Hey,
I have the same problem, holds a accidental note. It is rare, but it is. I think that one of the HD14051 can also be guilty. Ongoing search for.
I also have another problem, volume slider does not work smoothly, but immediately goes to the volume. I cleaned it, did not help. I gave the new did not help. I wonder will look for the problem.
Any ideas?
Hi,
I have a couple of questions about the JX-8P, I hope you can help me. I plan to open it up soon to fix some problems:
1. The hold pedal jack is missing. What type of jack do I need? Are the hold pedal jacks same as the output jacks? Does it have to be a specific model or will any jack work?
2. The 9-16 buttons don’t work. They used to go out after the synth was played for a long time, and then come back on again after a day or so, but now it seems they have completely stopped working. Do you know what could be wrong with that?
There are also some other problems – the aftertouch doesn’t work, sometimes notes keep on playing after I release the keys, and the volume knob is jumpy, but I think I already know how to fix this.
Thank you very much in advane.
Greetings,
Bojan