the replies (some are me):
Some of the soldering on those jumpers looks pretty dodgy and you might get lucky by reflowing it.
But frankly I (and most techs?) would steer completely clear of this project, too much history, too much blame-game, too many people working on it a little bit, etc.
Recapping can create more problems than it solves, I wouldn't recommend recapping anything until you're absolutely certain the caps are actually causing a problem.
_________________________________________________________________________________________
I agree with [], whomever did that work to the synth did a horrible bodge job. It reminds me of the crap work I used to do when I was learning to solder {cough}ty years ago. If that came from a pro shop there’s no way they could expect to stay in business.
The problem you are experiencing and describing now is most likely related to either the power supply section or the reset circuit or oscillator of the CPU. Randomly replacing parts is more likely to break something else so this needs proper troubleshooting using a schematic/service manual and following the voltages through preferably with an oscilloscope rather than a DMM or multimeter.
Absolutely do not recap your entire synth if you do get it working. Someone somewhere got lucky doing a capacitor bulk swap and managed to fix their (whatever it was, not necessarily even a synth) and that became some kind of thing that you just have to do, whether or not your symptoms relate to a bad capacitor. You are more likely to cause more damage than you fix, if you are even lucky enough to happen to accidentally find and change a couple of bad caps, and from your own skills summary you would have no idea how to proceed in finding and fixing the faults you introduced. Japanese PC boards of that era do not take well to the heat that would be required to desolder the old caps, much less the added stress from soldering in new ones. The adhesive bonding the copper to the substrate was already poor the day they built the boards, and it dos not age well at all. I know this because I used to repair a lot of consumer products made from the late 70’s to mid-80’s. All the missing pads and traces you already have are evidence of the fact that unnecessary rework is going to cause more damage.
Also you will probably throw out dozens of perfectly good capacitors while replacing them with today’s latest technology which is just mediocre by comparison.
I’ve taken on some real dogs for repair, but like Adam, this is not something I would ever put on my bench unless I were parting it out. There is no way of telling just how much other damage there is, and you might not welcome a large repair bill for something that can’t be fixed. It is reasonable and customary to pay for diagnosis even if the repair isn’t carried out, and it’s also reasonable to determine that ordering an expensive replacement board or three is going to cost you way less than the potentially dozens of hours of labor trying to patch that monstrosity back together, including trying to repair or reverse the damage the last artiste caused if that’s even possible. I would never give any kind of warranty on a device some other person butchered because even if I reworked and tried to repair the damage, there’s likely to be more that’s not visible. Plus, vintage electronics, especially from certain eras and manufacturers, are not prone to stay working for very long
_________________________________________________________________________________________
ME:
ok so apparently the jumpers are because circle pads have been removed accidentally from soldering, and someone I trust's experience here said Japanese boards from this era are notorious for such problems so I wouldn't bother even working on it. And IDK if the tech from threewave did this or someone before him but if it were threewave then I'd be even more warry of working on this as that guy is probably a synth-repairing-wizard when he's locked in so for it to happen to him means it's not easy. I still might though try to re-cap the main board as I need that for my other JP with low volume&distortion due to failed caps.
I'll be easier to snap some photos, measure weight and part it out online as-is and still make back about the same amount VS opening a worse can of worms working on it and spending more time than selling plus hopefully I make a lot of people happy with spare parts which are getting very rare. I really wish Roland would made a new version of this synth the layout is my fav of any synth probably. Feedback OSC is great too.
The only suggestion for why it actually doesn't work though was:
The problem you are experiencing and describing now is most likely related to either the power supply section or the reset circuit or oscillator of the CPU. Randomly replacing parts is more likely to break something else so this needs proper troubleshooting using a schematic/service manual and following the voltages through preferably with an oscilloscope rather than a DMM or multimeter.
_________________________________________________________________________________________
It is reasonable and customary to pay for diagnosis even if the repair isn’t carried out,
ME: Absolutely agree, I do this all the time with car mechanic, 'charge me whatever you want to figure out what's wrong and if I think I can do the work following youtube tutorials I'll do it myself otherwise how much for the repair too?' But from what I remember with threewave the diagnosis was free once I OK'd the repair quote. Either way whatever, hopefully all the parts go to someone who really needs them. I love this synth for the layout, the sliders instead of knobs of filter to simultaneously tweak them, can do a lot simultaneously with the left side LFO and Joystick, and the Feedback osc esp on Bass notes and sweeping the 'Harmonics' is really unique.
______________________________________________________________________________________
ME:
ok thanks I really appreciate the replies. I'll just part it out and not go crazy. It may take some time to sell everything but it's small parts. I can put the main board in my other JP-8000 which developed the common bad-caps distortion/low volume problem to test, this broken one didn't develop the low-volume problem yet when it died, but there's so many fragile ribbon connections to the main board that I'm not sure it's worth messing with, I don't trust the build of this synth, some ribbons aren't pins they're like crimped flat paper thin and then shaved down to expose the aluminum connections I don't want bending when popping in.
I've done a small amount of through-hole soldering replacing pots etc but yes one tutorial about the cap-swap said it's very easy to lift the pads for these surface-mounted and mess up the main board, so I'll probably mail it out to a tech and if I can get it re-capped for like $250 (parts are only like $20) then that's cool, but since I basically have a spare back up I can try it myself. I picked a stereo out of the trash that I can practice a lot on but IDK if there's surface mounts. One tutorial said he went ahead and re-capped everything else on the board, he didn't sound as experienced as another and most others say it's just the caps on the main board, which cause the low volume/distortion as they weren't made to take heat for even only 20 years of average use. So it'd just do the ~20 caps on the main board. All are the same except for 2,
Also according to the eBay seller:
https://www.ebay.com/itm/286077307895
This model is prone to main board failures that cause the sound to become extremely quiet, and there are companies that will repair it by sending out just the main board.
The faulty part is the mute circuit that prevents the popping sound that occurs when the power is turned on and off.
At our store, we have made a modification to deliberately disable this mute circuit (by cutting one of the jumper wires on the interface board).
As a result, the problem of the sound becoming quieter due to a fault in the mute circuit will no longer occur in the future.
However, there are also the following disadvantages.
When turning the power on or off, you will need to make sure that the sound does not come out of the amplifier or mixer (PA, etc.) that you have connected beforehand. (There is a possibility that the amplifier or speakers will break if a loud sound suddenly comes out.)
For those who are familiar with mixer operation or guitarists, it is a normal procedure to turn down the volume before operating the power or plugging in or unplugging the shielding.
If you remove the plate on the bottom of the synth, you can easily access the cut jumper wire and put it back in place.
If you send the main circuit board for repair, you will need to put the jumper wire back in place.
Here's the eBay listings for the re-cap kit, there's 105C is good but only 5K hours not 20 like the blue-LED modded thing I linked he used.
https://www.ebay.com/itm/265940571087
https://www.ebay.com/itm/275647226200
I'm surprised three wave did this, if you google that, check the yelp etc you'll probably be impressed with the shop, He's since moved location and focus more on new gear etc it seems, but when I brought it there and also stopped in a couple times it was just the one ~50 year old asian guy alone and sometimes had like an 18 year old kid that seemed to know nothing about anything just basically watching the shop while the owner worked on stuff in the back rooms. Drove a nice BMW SUV, warehouse full of liek quarter million dollars of gear, some of it customers' though but anyway seemed basically like some guy that really knew what he was doing. Also some to find the screws that hold the board in are not machine screws which screw into metal threads, they screw into plastic threads which is ok if you're careful but this guy takes a wood drill to your synth and he stripped every single screw on the board and it's barely holding, the shells keeps it all together but he butchered this thing.
What was he even trying to do with these jumpers? EDIT: I guess there's missing Round pads on the through-hole connections shown in photos either done by three wave or someone prior (I think if it were someone prior three wave would have mentioned it to me that someone else botched a prior repair) and so he jumped the pins to something else.
All the missing pads and traces you already have are evidence of the fact that unnecessary rework is going to cause more damage.
_________________________________________________________________________________________
The jumpers look like they're intended to replace pads / traces that lifted off the board while replacing parts - for instance:
https://imgur.com/a/aacXTfB#A0ZZBVj
Just above the right-hand end of the red jumper, you can see a circle of bare fiberglass where there should be a pad.
Some of the soldering on those jumpers looks pretty dodgy and you might get lucky by reflowing it.
But frankly I (and most techs?) would steer completely clear of this project, too much history, too much blame-game, too many people working on it a little bit, etc.
Recapping can create more problems than it solves, I wouldn't recommend recapping anything until you're absolutely certain the caps are actually causing a problem.
_________________________________________________________________________________________
I agree with [], whomever did that work to the synth did a horrible bodge job. It reminds me of the crap work I used to do when I was learning to solder {cough}ty years ago. If that came from a pro shop there’s no way they could expect to stay in business.
The problem you are experiencing and describing now is most likely related to either the power supply section or the reset circuit or oscillator of the CPU. Randomly replacing parts is more likely to break something else so this needs proper troubleshooting using a schematic/service manual and following the voltages through preferably with an oscilloscope rather than a DMM or multimeter.
Absolutely do not recap your entire synth if you do get it working. Someone somewhere got lucky doing a capacitor bulk swap and managed to fix their (whatever it was, not necessarily even a synth) and that became some kind of thing that you just have to do, whether or not your symptoms relate to a bad capacitor. You are more likely to cause more damage than you fix, if you are even lucky enough to happen to accidentally find and change a couple of bad caps, and from your own skills summary you would have no idea how to proceed in finding and fixing the faults you introduced. Japanese PC boards of that era do not take well to the heat that would be required to desolder the old caps, much less the added stress from soldering in new ones. The adhesive bonding the copper to the substrate was already poor the day they built the boards, and it dos not age well at all. I know this because I used to repair a lot of consumer products made from the late 70’s to mid-80’s. All the missing pads and traces you already have are evidence of the fact that unnecessary rework is going to cause more damage.
Also you will probably throw out dozens of perfectly good capacitors while replacing them with today’s latest technology which is just mediocre by comparison.
I’ve taken on some real dogs for repair, but like Adam, this is not something I would ever put on my bench unless I were parting it out. There is no way of telling just how much other damage there is, and you might not welcome a large repair bill for something that can’t be fixed. It is reasonable and customary to pay for diagnosis even if the repair isn’t carried out, and it’s also reasonable to determine that ordering an expensive replacement board or three is going to cost you way less than the potentially dozens of hours of labor trying to patch that monstrosity back together, including trying to repair or reverse the damage the last artiste caused if that’s even possible. I would never give any kind of warranty on a device some other person butchered because even if I reworked and tried to repair the damage, there’s likely to be more that’s not visible. Plus, vintage electronics, especially from certain eras and manufacturers, are not prone to stay working for very long
_________________________________________________________________________________________
ME:
ok so apparently the jumpers are because circle pads have been removed accidentally from soldering, and someone I trust's experience here said Japanese boards from this era are notorious for such problems so I wouldn't bother even working on it. And IDK if the tech from threewave did this or someone before him but if it were threewave then I'd be even more warry of working on this as that guy is probably a synth-repairing-wizard when he's locked in so for it to happen to him means it's not easy. I still might though try to re-cap the main board as I need that for my other JP with low volume&distortion due to failed caps.
I'll be easier to snap some photos, measure weight and part it out online as-is and still make back about the same amount VS opening a worse can of worms working on it and spending more time than selling plus hopefully I make a lot of people happy with spare parts which are getting very rare. I really wish Roland would made a new version of this synth the layout is my fav of any synth probably. Feedback OSC is great too.
The only suggestion for why it actually doesn't work though was:
The problem you are experiencing and describing now is most likely related to either the power supply section or the reset circuit or oscillator of the CPU. Randomly replacing parts is more likely to break something else so this needs proper troubleshooting using a schematic/service manual and following the voltages through preferably with an oscilloscope rather than a DMM or multimeter.
_________________________________________________________________________________________
It is reasonable and customary to pay for diagnosis even if the repair isn’t carried out,
ME: Absolutely agree, I do this all the time with car mechanic, 'charge me whatever you want to figure out what's wrong and if I think I can do the work following youtube tutorials I'll do it myself otherwise how much for the repair too?' But from what I remember with threewave the diagnosis was free once I OK'd the repair quote. Either way whatever, hopefully all the parts go to someone who really needs them. I love this synth for the layout, the sliders instead of knobs of filter to simultaneously tweak them, can do a lot simultaneously with the left side LFO and Joystick, and the Feedback osc esp on Bass notes and sweeping the 'Harmonics' is really unique.
______________________________________________________________________________________
ME:
ok thanks I really appreciate the replies. I'll just part it out and not go crazy. It may take some time to sell everything but it's small parts. I can put the main board in my other JP-8000 which developed the common bad-caps distortion/low volume problem to test, this broken one didn't develop the low-volume problem yet when it died, but there's so many fragile ribbon connections to the main board that I'm not sure it's worth messing with, I don't trust the build of this synth, some ribbons aren't pins they're like crimped flat paper thin and then shaved down to expose the aluminum connections I don't want bending when popping in.
I've done a small amount of through-hole soldering replacing pots etc but yes one tutorial about the cap-swap said it's very easy to lift the pads for these surface-mounted and mess up the main board, so I'll probably mail it out to a tech and if I can get it re-capped for like $250 (parts are only like $20) then that's cool, but since I basically have a spare back up I can try it myself. I picked a stereo out of the trash that I can practice a lot on but IDK if there's surface mounts. One tutorial said he went ahead and re-capped everything else on the board, he didn't sound as experienced as another and most others say it's just the caps on the main board, which cause the low volume/distortion as they weren't made to take heat for even only 20 years of average use. So it'd just do the ~20 caps on the main board. All are the same except for 2,
Also according to the eBay seller:
https://www.ebay.com/itm/286077307895
This model is prone to main board failures that cause the sound to become extremely quiet, and there are companies that will repair it by sending out just the main board.
The faulty part is the mute circuit that prevents the popping sound that occurs when the power is turned on and off.
At our store, we have made a modification to deliberately disable this mute circuit (by cutting one of the jumper wires on the interface board).
As a result, the problem of the sound becoming quieter due to a fault in the mute circuit will no longer occur in the future.
However, there are also the following disadvantages.
When turning the power on or off, you will need to make sure that the sound does not come out of the amplifier or mixer (PA, etc.) that you have connected beforehand. (There is a possibility that the amplifier or speakers will break if a loud sound suddenly comes out.)
For those who are familiar with mixer operation or guitarists, it is a normal procedure to turn down the volume before operating the power or plugging in or unplugging the shielding.
If you remove the plate on the bottom of the synth, you can easily access the cut jumper wire and put it back in place.
If you send the main circuit board for repair, you will need to put the jumper wire back in place.
Here's the eBay listings for the re-cap kit, there's 105C is good but only 5K hours not 20 like the blue-LED modded thing I linked he used.
https://www.ebay.com/itm/265940571087
https://www.ebay.com/itm/275647226200
I'm surprised three wave did this, if you google that, check the yelp etc you'll probably be impressed with the shop, He's since moved location and focus more on new gear etc it seems, but when I brought it there and also stopped in a couple times it was just the one ~50 year old asian guy alone and sometimes had like an 18 year old kid that seemed to know nothing about anything just basically watching the shop while the owner worked on stuff in the back rooms. Drove a nice BMW SUV, warehouse full of liek quarter million dollars of gear, some of it customers' though but anyway seemed basically like some guy that really knew what he was doing. Also some to find the screws that hold the board in are not machine screws which screw into metal threads, they screw into plastic threads which is ok if you're careful but this guy takes a wood drill to your synth and he stripped every single screw on the board and it's barely holding, the shells keeps it all together but he butchered this thing.
What was he even trying to do with these jumpers? EDIT: I guess there's missing Round pads on the through-hole connections shown in photos either done by three wave or someone prior (I think if it were someone prior three wave would have mentioned it to me that someone else botched a prior repair) and so he jumped the pins to something else.
All the missing pads and traces you already have are evidence of the fact that unnecessary rework is going to cause more damage.
_________________________________________________________________________________________
The jumpers look like they're intended to replace pads / traces that lifted off the board while replacing parts - for instance:
https://imgur.com/a/aacXTfB#A0ZZBVj
Just above the right-hand end of the red jumper, you can see a circle of bare fiberglass where there should be a pad.
Statistics: Posted by bbing531 — Fri Nov 22, 2024 12:10 pm