Modulation Button - JP8

General Discussions concerning modifications to the Roland Jupiter series analogue synthesizers
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Darran
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Joined: Fri May 25, 2007 8:48 pm
Location: Rotherham
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Modulation Button - JP8

Postby Darran » Sat Sep 29, 2007 1:52 pm

Does anyone have a walkthrough to cleaning the Modulation Button on a JP8.

I don't want to open it all up to find there is a single screw to drop out a panel method, like what I normally find!

Darran
current kit list:
Roland Jupiter 4
Roland Jupiter 8
Roland JP-8000
Alesis Andromeda A6
Roland XP-50
Roland V-Synth (vc-1 and vc-2)
Yamaha W7
General Music S2
Kurzweil K2000
Roland D-110
Korg Microkorg
Akai S3000 XL
Yamaha TX7

User avatar
Darran
Posts: 4
Joined: Fri May 25, 2007 8:48 pm
Location: Rotherham
Contact:

Postby Darran » Sat Oct 27, 2007 11:58 am

121 views and nobody to help.

ok, I wave some spare time over next weekend, I shall rip my unit apart and photgraph my way through, so if anything others can take something from my experience!

wish me luck!

Darran
current kit list:

Roland Jupiter 4

Roland Jupiter 8

Roland JP-8000

Alesis Andromeda A6

Roland XP-50

Roland V-Synth (vc-1 and vc-2)

Yamaha W7

General Music S2

Kurzweil K2000

Roland D-110

Korg Microkorg

Akai S3000 XL

Yamaha TX7

7hz
Posts: 46
Joined: Mon Sep 24, 2007 11:04 pm

Postby 7hz » Sat Oct 27, 2007 12:50 pm

This forum is a bit... uh... silent, isn't it?

I guess ppl don't come here unless they need something :-(

cs1729
Posts: 6
Joined: Tue Oct 09, 2007 8:21 pm

Postby cs1729 » Sat Oct 27, 2007 4:25 pm

I'm not exactly sure, but I believe that the modulation button (lfo 2) on the Jupiter 8 is the same switch as the Jupiter 6 which is the same as the MC-4. If so, then you can repair the switch 2 ways.

1. Buy another from chipforbrains on ebay or track one down (alps-1).

2. Assuming no damage to the plastic or rubber stop, repair the switch with a rubber keypad repair kit. (I.E. Chemtronics Circuitworks Rubber Keypad Repair Kit, http://www.partstore.com/Part/Chemtroni ... 5/New.aspx)

To repair: remove the switch, take it apart, take out the rubber stop, mix the solution, paint it on the contact circle, let dry 6 hours and reassemble.

It would be cheaper to just buy a replacement switch than the kit, but if you have an MC-4 that needs new switches or something then you can kill multiple things at once. The solution is only good for about 24 hours (even though it says 72) so you pretty much have to do everything that you are going to do in one or two gos so it is not really worth it to buy the repair kit unless you have more than one switch to repair since you can't save the solution, but it is an option if you can not track down a replacement switch. I also need 2 replacement switches for an MC-4, because I can not repair them (the plastic is broken) and I am trying to get chipforbrains to sell me some.

Keep in mind that the switch may not be what I am thinking it is, but I am fairly sure about it. You will know I'm wrong if it is not an ALPS-1.

EDIT: I just checked the old auction that chipforbrains had up and according to him, I am right about the switch being the same.
( http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0156941755 )
Last edited by cs1729 on Sat Oct 27, 2007 4:54 pm, edited 2 times in total.

cs1729
Posts: 6
Joined: Tue Oct 09, 2007 8:21 pm

Postby cs1729 » Sat Oct 27, 2007 4:28 pm

To answer your original question, I don't know how to disassemble the JP-8 (or even the JP-6 since I've just got it and haven't had the need) , but you can not simply clean this type of switch. If it is misfiring, then it needs repaired with a new contact surface or replaced.

xresonance
Posts: 5
Joined: Fri May 02, 2008 8:25 pm
Location: Buffalo NY
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Postby xresonance » Sat Nov 29, 2008 7:47 am

I just successfully dismantled and cleaned that switch an hour ago. It was getting wonky on me for a while, and since I was knee-deep in the jp anyhow, I pulled it out. Desoldered the four points on the bender board, then pushed in the retaining tabs that hold it into the metal frame.

After it was out, there are two small plastic clips on either side that can be pried up gently with a fingernail till they just pop off, and then the switch slides apart. You will see the plastic button, a spring, and a rubber cap. Under the rubber cap are two contact points. On the bottom of the rubber cap itself is a carbon thingie, like in remote controls and game controller buttons.

To clean it, I took some clean cotton swabs and strong isopropyl alchohol, and scrubbed the heck out of the metal contacts and the black rubber nubbin. Made sure there was no grease, etc, on anything. Reassembled, and it tested far better. I was getting 200-50 khoms before when it was misfiring, and after the cleaning it was more like 20-5kohms. Reassembly is the reverse of disassembly. Pop it together, pop into hole, resolder nicely. Worked like a champ for me.

Synthfool
Posts: 99
Joined: Mon Mar 05, 2007 8:06 pm
Location: Wrightwood, CA
Contact:

Postby Synthfool » Sat Nov 29, 2008 7:24 pm

I hope I'm not a downer, but don't be surprised if this button fails again.
I've never found cleaning or even abrasion to work very well for long.
The resistance you're reading is fairly high too.

I've also not found that coatings work all that well.
I've used silver paint and they still fail after time.

What I *have* found works and for many years is supergluing a small piece of copper to the rubberized contact plunger.
I've done that to many JP8's, CR5000/8000s and even my own B&K multimeter.
Never a problem and the resistance hits 0 ohms.
Sounds hokey, I know.

But I did this to my multimeter 12 years ago and it's worked great since.
Another CR8000 owner recently told me their machine was still fine after 10 years.

xresonance
Posts: 5
Joined: Fri May 02, 2008 8:25 pm
Location: Buffalo NY
Contact:

Postby xresonance » Mon Dec 01, 2008 8:13 pm

Synthfool,

I wouldn't be surprised if it went out again, being as old as it is. I've never been a fan of that style of button. I was actually impressed by the condition of the rubber bit in there, would have expected it to have been eaten up a bit more from age. Good idea with attaching some actual metal inside - I will likely try something along those lines next time it asks for help. I've got more business inside that thing anyhow =)

nick
Posts: 1
Joined: Fri Feb 19, 2010 9:00 pm
Location: UK

jp-8 bender assambly

Postby nick » Mon May 10, 2010 5:41 pm

Hi. I also have an issue with my JP-8 mod switch but unfortunately one of the fixing screws has a damaged head so I can't remove the panel.If I were to drill the head off (very carefully) would this facilitate the removal of said panel or would this be a "bad idea!" ?.
I realise this thread is old but i'm hoping someone will find this question snd be able to offer some useful advice.
many regards, Nick


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