Roland JD-800 Programmable Synthesizer


Last week I bought a Roland JD-800 🙂 It needs a little bit of attention though. It’s been heavily used and was sold ‘as is’. It hadn’t left it’s flightcase in 5 years and it was stored in it because a lot of keys didn’t work anymore. It was just the flightcase and JD-800 so no manuals or powercord.

Technical specifications:

  • Polyphony – 24 voices
  • Oscillators – ROM based digital synthesizer
  • #Instruments – 6 part multitimbral
  • Keyboard – 61 key keyboard with velocity and aftertouch
  • Arpeg/Seq – NO
  • Control – MIDI
  • Date Produced – 1991-93

At home I plugged it in crossed my fingers and hoped for the best. But it started up without problems 🙂 Well, just a message that said the backup battery was low but that’s not a problem. I plugged in my headphones and gave it a quick test. Indeed in the center of the keyboard a lot of keys didn’t work but on the left and right side they worked fine. The keybed of the JD-800 is sort of identical to the U-20, D-5 and D-70 and I have taken apart several of those so I believe the problems with this JD-800 are fixable. Can’t wait to take it apart!

Did I mention it is very dirty? 🙂

 20150616_210527 (Medium) 20150616_210511 (Medium)

Before I take it apart I will put it in test mode to see if all the buttons and sliders still work. I think it needs several new black keys because some are kind of wobbly. Luckily I got a whole bag of spare keys with a U-20 I bought last year. These keys are identical to the JD-800.

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Like pretty much everything Roland made in the late 80’s and early 90’s this JD-800 had the ‘red glue’ problem with the keys. It’s the red glue used to glue metal plates underneath the keys that starts running after 20 years causing all kinds of problems. Usually keys that are stuck so you can’t press them anymore. With this JD-800 it wasn’t really a problem yet but because I’m taking it apart anyway I’ll just fix this before it becomes a problem. Here some more ‘before pics’:

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Time to break out the screwdrivers 🙂

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Items I removed from this JD-800 include (but are not limited to):

  • Lays Crispy Chips (Classic flavor)
  • Someone’s dentures
  • A phonebook
  • Chewbacca (at least he lived in there for a while…)

Before I removed the keybed I played the JD-800 for another 5 minutes and I must say that it works pretty well. Okay, there are about 20 keys in the center of the keybed that don’t work but pretty much all the buttons work. “Pretty much” because the ‘Value <‘ and ‘Value >’ buttons don’t seem to work and you need those + the Exit button to put it in Test Mode. So I haven’t been able to test all 59 sliders.. the volume slider doesn’t work really well so I can only hope the other 58 are in better shape.

The design of the JD-800 is really clever concerning the sliders. As you can see in the photo’s the sliders appear to be closed instead of open. This is the first Roland I own that uses this configuration. It prevents dust from having easy access to the sliders. Still I’m afraid looking at the condition of the synth that enough dust got in anyway. Well see.. Here are some photo’s of the keys: 20150621_153736 (Medium) 20150621_153810 (Medium) 20150621_153841 (Medium) 20150621_154013 (Medium)

In the last picture you can see the top parts of 2 black keys. The one on the left is missing a tiny bit of plastic. This results in this key being very wobbly.. it can move from left to right a few mm’s. You could still use it but I’m going to replace them. I have 9 spare black keys but I need 15.. hmmmmm.. might ‘borrow’ some from a project U-20 I have lying around. The keybed assembly is absolutely filthy 🙂 I’m hoping cleaning everything will make all the keys work again. The grey rubber strips contain the contacts that make the keys sound.

20150621_154051 (Medium) 20150621_154054 (Medium) 20150621_154458 (Medium) 20150621_154503 (Medium)


First the keys. I’ve fixed this red glue problem 7 times before and it’s pretty easy. All you need is Caustic Soda (Sodium Hydroxide with water: this is draincleaner, be carefull!). Put a little of this stuff in some luke warm water and add the keys.

20150621_154533 (Medium) 20150621_155014 (Medium) 20150621_155846 (Medium) 20150621_155849 (Medium)

Now have a beer.

A couple beers later:

20150621_191850 (Medium)

The red glue is almost gone. The weights are still in keys though. Refresh Caustic Soda and have another beer.

After all the weights have dropped clean the keys and the weights. Glue the weights back into the keys.

The first couple of times I did this I was wearing a Walter White style Hazmat suit but nowadays I wear flip flops and a tshirt while doing this. Just be carefull and don’t get this stuff on your skin or in your eyes. Rinse with water if you get it on your skin. It feels soapy (because it’s one of the ingredients of soap..) but after a little while it will start burning 🙂 Remember the main use for this stuff is to remove anything from your drains that shouldn’t be there. Walter White might also use this to get rid of other things. Not sure. 🙂 I use about 25 to 50 grams per liter of water. Buy at Kruidvat (NL) for 2 euro’s. You probably need to refresh the solution 2 or 3 times before all the weights will drop out of the keys. No tools required. The weights will drop out of the keys all by themselves! Just replace the solution if the weights are still stuck after a 2-3 hours of soaking.

Will update soon!

Update 2015-07-16:

I soaked the keys in caustic soda to remove the weights, thoroughly washed them, polished them, washed them again, reglued the weights:

20150704_084804 (Medium)

The JD’s teeth are looking pretty freakin’ white again as you can see 🙂 I’ll put some ‘before’ and ‘after’ pics right next to each other later on so you can see how much it cleaned up.

I also removed the huge pcb’s that contain the sliders and cleaned everything:

20150623_092910 (Medium) 20150623_095016 (Medium)20150623_095009 (Medium) 20150623_093141 (Medium)20150623_093139 (Medium) 20150623_093130 (Medium)20150623_092928 (Medium) 20150623_092921 (Medium)20150623_133515 (Medium) 20150623_133519 (Medium)20150623_131651 (Medium) 20150623_131645 (Medium)20150623_095043 (Medium) 20150623_095040 (Medium)

Yes, that was a lot of work. I cleaned all the black plastic parts in the kitchensink with soapy water and a toothbrush..

I have enough spare keys so unfortunately your services are no longer required:

20150704_084550 (Medium)

Next I cleaned the keybed:

20150704_093705 (Medium) 20150704_094205 (Medium) 20150704_093318 (Medium)

Make sure you clean all the black stripes and dots. I used Q-tips and 97% cleaning alcohol. You can see a lot of dirt / dust on the pcb. That is probably the reason why some keys didn’t work..

Last weekend I put the whole thing back together and it’s starting to look pretty good 🙂 Haven’t had time to power it up again to see if everything works.. Will try to do so this weekend. I’ll post some pics of the reassembled JD-800.

Update 2015-07-20:

I’ve powered it up! Tested all the sliders and they all work! YEAH! (they are about 10 euro’s each so with 59 potential problems that could have gotten a bit expensive)

Remember I told you that about 20 keys didn’t work at all? Well, I have news: they still don’t work :’)


It’s about half the second and third octaves. The keys are all consecutive so it’s probably a cable issue. I’ve measured the flatcable connecting the keybed to the mainboard and that’s fine. It’s probably the super fragile flexible PCB underneath the keys. Bummer. I’ll have to take all the keys of and do some measurements. It’ll be fine though. Promise.

Update 2015-08-06:

I’ve partially taken apart the keybed again to find the problem. This is about the area that doens’t work. If you look closely I’ve marked the top of the green PCB with a black marker to indicate the area:

20150806_202941 (Medium)

As you can see in this closup it’s exacly two series that don’t work (follow the traces):

20150806_202948 (Medium)

I’ve tested the circuits and traces 9 and 11 are open.. The problem is not in de extremely fragile connector on the far left of the keybed but in the flexible green PCB somewhere. I’m going to make 2 bypasses by glueing 2 wires with electrically conductive ‘Wire glue’ on the traces. The green PCB is made of very thin plastic so you can’t solder on it because you’ll burn right through it. I’ve done exactly the same repair on my Roland U-20 and that’s been working fine for years ever since so I think I can fix this as well.

Before I took it apart I’ve put the JD-800 in test mode and did some tests. Everything seems to work fine except the aftertouch. This isn’t a real surprize because the aftertouch usually doesn’t work (very well) on old synthesizers. I’ll try and fix this too.

All the smudges on the steel frame where little spots of rust. I’ve used a ‘Scotch-brite’ pad to clean it. You can still see the spots but it feels smooth again. The inside of the entiry synth had this (and I cleaned it). Probably because it was stored in a garage for years..

Update 2015-08-09:

The Bypass. Since about 20 keys don’t work I can either choose to replace the PCB with the broken traces or try to fix it. The PCB is about 70-100 euro’s if I can get it at all so I’ll try to fix it first 🙂

This is how I did this:

 20150808_141353 (Medium) 20150808_141411 (Medium)

I carefully scratched open the trace with an exacto knife in two places and glued a bypass wire onto the open traces with something called ‘Wire Glue’. This glue conducts electricity so it’s perfect for this application.

After letting this dry for an hour I replaced the rubber contact strips, installed the keybed in the JD-800 and flicked the switch…

Everything works again!


I secured the wires with a few dots of regular glue to the PCB. Installed the keys and put half a million screws in the thing when closing it back up.

Here are some before and after pics 🙂

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20150621_142506 (Medium) 20150809_113116 (Medium)

20150621_150434 (Medium) 20150809_112929 (Medium)

 And some photo’s of the finished JD-800:

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Now all there’s left to do is play the damn thing 🙂

2015012932581 troll-face

Edit september 14th 2016:

Does this look alright?

I saw that the board directly above the psu is getting a little hot..


10 thoughts on “Roland JD-800 Programmable Synthesizer

  1. Oh man, this posting is so helpful!
    I have similar problems with my JD800. I got it for a steal, but so many problems! I’ve cleaned up red glue issue, fixed quite a few unresponsive keys, but now have a broken trace on the flexi pcb. I am going to try your fix, hope it works!
    Any ideas where I can find replacement keys, contract strips and especially key weights?
    About a quarter of my weights seemed to have disappeared before I received the unit..
    Thanks so much for posting this!


    1. The cheapest way to get replacement keys is to buy a Roland U-20. They are usually super cheap and they have the same keybed as a JD-800. The only difference (I think) is the flex cable going to the mainboard is very long on a U-20 and very short on a JD-800. So I don’t know if you can use the flexible part that’s underneeth the keys for your JD-800. I once got a whole bag of extra keys with a U-20 I bought and I’ve used quite a bit of them fixed other synthesizers in the meantime. I still have a few left but not enough for you I think.. I you live in the Netherlands (or europe) I might know a source for the keys and the weights.

      The contact strips of the U-20 are identical to the JD-800 by the way. You could also use parts from a D-70 and D-5 (only the D-5 has no weights..) I have never had to replace the contactstrips on one of these though.. Just a good clean with q-tips and alcohol always fixed it..

      Good luck with your repair!


  2. Awesome, thanks for the info!
    I got pretty much every key working by cleaning contact strips. Waiting for some conductive glue to try your jumper fix to get the top octave working. The only contact strip I need is the 13 pad top octave since one key’s rubber boot was literally ripped off. Im missing one key, the only unique one of the bunch, the high C. Im in the states and can likely glean these parts from ebay. The only thing I am having some trouble finding are the key weights, of which I need 8 for the white keys, but these arent a huge deal. Gonna tackle the aftertouch mod next to get this baby runnin full steam!

    Thanks again for your post, has been most helpful in (hopefully) resolving the broken pcb trace!


    1. Fascinating blog. Comprehensive and compelling.
      Query: I accidentally pulled apart the ribbon cable from the green contact board and regret it. Can you offer any advice on repairing this? I’ve considered redrawing the lines on the strips with coonductive paint but would not know how to thermally reattach them together.
      Any advice would be greatly appreciated.
      Thank you from the states
      Kenny k


      1. Hi Kenny,

        Look for the D-70 project on this blog. That D-70 had the same problem: the connector was loose and the entire left hand side of the keyboard didn’t work (D-70 has a connector like that on both sides of the keyboard)

        I tried to repair it with conductive silver glue first but that didn’t work. That glue is as thin as water and it constantly connected multiple traces. Then I switched to ‘Wire Glue’. This is a thick black conductive glue that works very well. On the D-70 I replaced the flatcable with 16 wires which I soldered to the PCB on the back of the keybed. Bit messy but it works perfect. If I were to do this repair again I would first try Wire Glue to repaint the 16 traces on both the green pcb and white flatcable, let that dry and then put the original flatcable back to see if that would work.

        I recently acquired another D-70 of which a lot of keys don’t work. I will post an article of the repair as soon as I have time for it.

        Good luck 🙂



  3. Nice post, I need to tackle mine as the red glue has gone everywhere.

    Your power supply board:

    Looks like you need to restore it before it blows up your synth. From the pic you posted all the capacitors are showing leakage and the PCB on the upper panel that sits above the PSU looks like it has started to burn from the heat and vapours from the PSU caps. Make sure they are discharged fully before touching them or they will give you a shock.

    The voltage regulators may be in need of changing also.

    Let me know what you get on!! Good luck!


    1. Hi Patrick,

      Thanks for the comment. I’ve added some photo’s to the bottom of the post showing closeups of the PSU and de board above it. I noticed it was getting a bit warm in there but the caps all look fine. Maybe I need to put something in between so the heat doesn’t damage the board.. the black stuff at the bottom of the caps is just glue holding them in place.

      grtz, Jorick


  4. Thanks jorick
    I’m currently doing just that: repainting the individual lines on both the ribbon &contact board for the last month . An arduous process to say the least. I will be attempting to fasten the plastic cover bar once the paint dries and post my results to you and this board.
    I used scotch tape between the lines to paint clean lines. I did notice if I pressed the two cables with a lot of pressure I received a couple of sounds of f two keys. As a corollary its definitely a contact issue. I am using the calkote contact paint. I did take a view of your other repair which is awesome.


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