Repairing some faults with a faulty Roland JX-3P synthesizer

[@lundsweden]

I love 80s Roland keyboards, this was peak Roland IMO '80-'90. My reasoning? Sure 70s Rolands are cool, but in 1980 we had the TR-808, '81 the Jupiter 8, '82 the Juno 6/60, 1983 the JX-3P, 1984 the TR-909 and Juno 106! In '85 we got the JX-8P, in '87 the D-50, '88 the S-Series samplers, '89 the R-5 and R-8 drum machines and the JD800 in 1990!

[@markusfuller]

nice repair. I loved my jx-3p many years ago and cannot remember why I ever sold it.

[@waheex]

hi At one point I had 3 of them, it was just getting silly. Just have the one now but a great synth

[@jeffperonto3234]

Good job. You must feel good to have succeeded with several problems this synth had.

[@waheex]

it can be rewarding after weeks of head scratching:)

[@sensemusicofficial]

i still have mine broken in the cupboard from about 20 years ago :\ .. it was my first synth .. i wonder what it would be .. it makes NO SOUND but everything turns on .. actually what you described FAINT sound

[@waheex]

might be just connectors and IC's need re-seeating. Certainly worth a try

[@makinamusica]

mindburner i have some dead white keys on my JX-3P i took it apart and the contact strips were good, so i ordered the TTM2365 CHIP. i hope that fixes it do you have any sugestions?

[@waheex]

yes could be a IC problem. Groups of keys maybe a 4051. It's been a while since I had the 3p apart so not sure if this is the case but it can be when an Ic dies

[@makinamusica]

Mindburner thank you. I ordered both The IC TMM2365 and the IC 4051 I will keep you posted thank you!

[@waheex]

@@makinamusica I suspect the 4051. They are notorious for failing in older synths. Usually suspect if a group of controls or notes fails at once. Worth swapping even if it's no the main issue. Good luck

[@makinamusica]

@@waheex I changed the TTM2365 CHIP and the dead keys still don't work. Also, i ordered the IC4051, but i wasn't aware there was 4 of them IC23/IC26/IC27/IC28 Do you know which one it might be by any chance? should i just order all four? I can pay pal you some money for you tech support! Sorry to bug, but it seems like you know alot more than i do. i can email you pics of the board.

[@ICanFixThat2]

Hi, I got one from eBay and sadly didn't test it, guess what, I it dead. I had another system board, exchange and worked. Any idea where to start finding? There was nothing when turning on, just swap with the other one and everything works (one voice is noisy but I was so lucky you show how to find it) Thank you so much, I was so frustrated today and you helped me a LOT!

[@waheex]

The JX tracks are quite small and fragile. Perhaps check that all solder joints look ok and use continuity meter to check this also.

[@RonnieAugeri]

What does your firmware version read out as when you power up holding down tone 9? Mine lights up bank A and tone 5, so must be version 1.5? Seems really old.

[@waheex]

mine shows bank D and tone 3 so. 4.3. I can't recall the version numbers off hand

[@erwanlebail2049]

Hello, I notice that you are talking about the sequencer which does not work correctly, it only plays the first note. Do you know where this problem comes from? Thank you

[@waheex]

hi, sounds like it may be an IC. Not sure which one is responsible for the sequencer though.

[@erwanlebail2049]

@@waheex Hello, I don't understand English very well, I thought you had the same problem on your JX3P. and that you had solved this problem. but thanks

[@snolan1990]

Really valuable detail in this. Thanks for sharing!

[@waheex]

great, glad it's of help

[@newmusic4059]

great video, have a Jx3p with a similar 'all lights' fault so you have given me a great starting point thanks...

[@waheex]

best of luck with the fix

[@TanTanBEATS]

Hi! Thanks for a great video. Learned a lot! Just have a question. I have a jx3p with no sound and the buttons are randomly flashing while pressing them. I tried the test point 7 as you did in the video but I still cant hear anything. What would you check after this? The IC 102s?

[@waheex]

The RAM on these can cause issues. Hard to troubleshoot in the board so I ended up just replacing them. Also, Check the socketed IC's are all pushed in tight. 40 logic chips can also be highly suspect

[@levihockey2652]

How did you remove the NAND 4011 Gate? All I have is a soldering iron and I am trying to remove the old one.

[@waheex]

a solder sucker, or solder wick . A dedicated solder remover gun is great but expensive if only used a few times

[@alan933]

mine has a lot of static in the volume knob, can it be cleaned out or does it need to be replaced? My JX has worked great but I remember times during hot summer months with high humidity the buttons would not work right.

[@waheex]

cleaning usually works for a while, sometimes for quite some time. It depends if the carbon on the pot tracks is worn too much. If it is, then it's replacement time.

[@Howdy606]

Great vid. I got a JX3P with a dead battery. C and Dbanks not saving patches. Is it possible to replace it without taking the board out? I'm ultra worried about breaking something taking that large board out.

[@waheex]

Thanks. It could be possible but risks damage to the PCB when trying to remove the battery. It is one of those cases where doing it right and removing the board, might actually save time in the long run. You could however try and snip the battery off and then run wires to an external battery if you are careful.

[@Howdy606]

@@waheex Thanks for tip :). I will snip it I think. Will run wires to a button battery holder and Velcro it to the chassis away from the board. I read the original battery type isn't the same type as the one in the Korg Polysix and generally doesn't leak as badly when they age,

[@kimbojaap]

Thank you for the video :) I'm also having problems with this old beauty! It responds over midi just fine, but none of the keys work! Do you have any idea what this might be?

[@waheex]

could well be bad connector on the keyboard or controller IC. Worth checking the connector 1st cheers

[@Lhenndyn]

Excellent ! I’m actually trying to fix mine, and it’s a pain... the leds are sometime all off, sometime some of them are on, randomly at start... but no control, no sound... so I changed the rom (from a serious seller, I believe), the the CPU (like you by a 8031, as the internal ram of the 8051 is not used by the synth). Then the ram... still nothing new, random lights at start. I think I will change some more chips but I don’t know where to start. Do you have an idea ? And by the way, what is the chip tester you use on the video, could be very useful ! Is it working for any kind of chip ? Anyway, thanks a lot for the video, I’m feeling less alone :)

[@waheex]

I would say 40 logic IC's to be replaced. I can't remember exactly which ones on the JX3p as i'm up to my neck in Prophet 5 at the mp, but think they're 4016 or 4066. The IC tester is available on Aliexpress. I just made a little mount for it. It's pretty handy

[@Lhenndyn]

Mindburner thank you for your answer ! I will check that first, I’ll tell you :)

[@GlitchElectronica]

Great video! But unfortunately... I have a JX-3P with the same type of problem: sound is really really weak on outputs as on headphones. I changed 1uf, 47uf and 100uf caps, CPU for new ones, with no success. Also 4558 near "Poly Out" TP has been replaced. Last thing, on working presets, notes are infinite, as if sustain was full on... Any idea? What can I check first after all that..?

[@waheex]

hi it does actually sound like it 'may' be BA662 unfortunately, perhaps one part of the internal electronics has give up. The sustained notes could be an issue with the envelope IC's but if it's on all voices, then perhaps bad 40 logic in that area.

[@jackflynn-oakley1937]

How did you fix the volume knob connector?

[@waheex]

just a reflow with solder If I remember

[@grerknroll]

Great video I have Roland Jx 3P It has problem with sens slider So I put a new sens slider and It’s still not working.I can’t edit parameter by sens slider Where should I start to look for the problem (I replace rate slide a new one too sequencer is working but It can’t write note ,just start play same note over again) Thanks !

[@waheex]

hi thanks for the feedback. It's possible there are many causes, but I would suspect some of the 40 logic chips are even a bad trace/solder joint. The slider may be working but the data is not getting through logic.

[@grerknroll]

@@waheex thanks hey i want to update. i just replace a ic4 chip found a broken pcb joint and problem solve. i can use sens slider to edit parameter now ! still has one problem is sequencer when i press start it play the same note i can adjust speed rate but i can't write any new note to it thanks !

[@waheex]

@@grerknroll that's great. It's so satisfying when you get a problem fixed. With regard to the sequencer, I think it's a timers and just one logic circuit so replacing the IC's there may well fix it

[@grerknroll]

​@@waheex come to update. sometimes sequencer works.It can record and start play note well but when it don't. all 16 light parameter just flick I don't know why that happend I'm look panel board circuit is IC7 and IC 6 is what i should check it? ( addition I measure R68 ( as it show in Panel board. it read 47k ohm .and I measure Ressitor R66(which suppose to be connect from R68 and it read 0 ohm is it normal ? could it be a broken Resistor R66 ? )

[@michaelprechter3539]

Thank you for making this video. I have a slightly different issue that I wonder if you've come across. I can power up the JX and the lights come on like normal. I can select different patches, but I don't get any audio output. There is a "wooshing" white noise sound when chorus is engaged, but nothing else. Have you heard of this before?

[@waheex]

hi sounds like it may be the final audio output, possibly the BA662 IC hard to say as it could be anything in the chain. The audio probe idea is worth checking out, see if you can get any other sound from the voice board.

[@michaelprechter3539]

@@waheex Thanks, I ended up taking it in for repair since it felt out of my skill level. Will report the issue once I know more.

[@tobycookie2198]

Great video! I have a JX3P with "all light on" problem when it turn On. So, after you traced all CMOS , tested and socketed, what were you doing exactly, replaced the 8031/8051 CPU's or replaced the TC5517 ram''s ? Pardon for my English as is not my native, and my hearing is so bad for fast speak too. :) Oh anyway, I'm really confident in electronics and had repaired a coupled an analog synthesizer too. And this is my first time dealling with hybrid synth. Cheers.

[@waheex]

HI THERE. I would say check out the RAM IC's as they can go bad on this synth. All 40 logic is suspect too. But personally I would do the RAM 1st then check the 40 IC's with a chip tester.

[@tobycookie2198]

Mindburner Hi, thanks for the reply. I already checked all the 40 Cmos with IC's tester, they seem quite good. Time for searching seller for the Ram ic's one. Any suggestion where I should looking for the part shop? Sorry to keep bothering you.

[@waheex]

@@tobycookie2198 no problem at all. I think I got mine on ebay, but there are various synth parts suppliers on the web which should carry the IC. I think it's used in VX600 synth and several others too. It's a relatively common chip

[@tobycookie2198]

Mindburner thanks, I'll find out :)

[@warp9988]

This is fantastic. If you didn't have the other system to probe out, do you think you could have figured this one out?

[@waheex]

thanks very much, I think I would have got it fixed but it would have taken a lot longer. It was a good learning curve

[@machiwoomiapoo]

Excellent video!

[@waheex]

thanks v much, will work on presentation for next one