ward

restoring vintage keyboards
« on: December 08, 2020, 09:01:23 AM »
Hey there,
I was wondering if we have people here with keyboard and synth repair experience.
The only experience I have is reviving a Roland D50.
It had several issues, but what I'm most interested in is if someone here has a durable solution for the keycontacts?
The fix you find most online involves using a pencil to make the contacts conduct again.
In my experience this is temporary.


Re: restoring vintage keyboards
« Reply #1 on: December 08, 2020, 09:27:16 AM »
I did a sucessfull repair to a Korg Prophecy keyboard recently , it was an issue with aftertouch not working on some keys . Dismantling the keybed and cleaning was the first step , I then layed a few layers of electrical tape on top of the sensor strip. Worked a treat , got better more consistant values of resistance with the keys pressed down. Back up battery replacement is another common issue in keyboards/synths . Finding out how to do a factory reset is also worth knowing , ocassionally firmware updates can help also. 

dmp

Re: restoring vintage keyboards
« Reply #2 on: December 08, 2020, 11:04:32 AM »
I am also interested in this. I restored a Farfisa and cleaning the key contacts was tough. It isn't 100%.
Other synths have been easier. Depends on the design.
Replacing electrolytic caps is a good idea on older synths. 

Re: restoring vintage keyboards
« Reply #3 on: December 08, 2020, 11:37:08 AM »
On more modern equipment theres usually a strip very much like you find in a tv remote , its rubber with preasure pads  ,I did know of a music shop back in the day that could order the button strips, long since shut their doors now .

I did own a Farfisa at one point , came to me in a lot which included a guitar amp .
The switching contacts comprised a gold wire running the lenght of the keyboard and another contact in each key , some of these were worn and had only partial or intermitant contact , I used a special silver loaded paint to build up the electrical contacts on the keys that were faulty ,worked great for years after. The silver paint I got from Maplin ,it was designed for pcb repairs ,came in a small glass bottle , cost about a fiver.

mjrippe

Re: restoring vintage keyboards
« Reply #4 on: December 08, 2020, 01:42:52 PM »
Hey there,
I was wondering if we have people here with keyboard and synth repair experience.
The only experience I have is reviving a Roland D50.
It had several issues, but what I'm most interested in is if someone here has a durable solution for the keycontacts?
The fix you find most online involves using a pencil to make the contacts conduct again.
In my experience this is temporary.

Are the keys pressing a rubber button with a carbon contact?  If so, you can clean off the contact point and use a dot of foil tape to replace the carbon.

walter

Re: restoring vintage keyboards
« Reply #5 on: December 10, 2020, 12:41:18 PM »
How do you use a pencil to make the contacts conduct again? I have used a pencil eraser to clean contacts. I have also used a trace repair pen to repair carbon traces under a membrane switch.
Blown like a fuse

ward

Re: restoring vintage keyboards
« Reply #6 on: December 10, 2020, 01:52:53 PM »
Thanks for all the input.
I decided to dive back in and try to find a more durable fix.
Seems like I need to track a trace repair pen.

In the attachment there's a photo of what the contacts look like... there are 4 contacts on the pcb for one key, two contacts on the rubber strip.

Whoops

Re: restoring vintage keyboards
« Reply #7 on: December 10, 2020, 02:00:34 PM »
It had several issues, but what I'm most interested in is if someone here has a durable solution for the keycontacts?

Are those pcb based where the the rubber button has a sort of carbon contact that touches the pcb?
can you post pictures?

If it's the same thing, I'm  also looking for a solution for this, this problem happens a lot in Roland SPDS units.

I tried a lot of different things with not much success.
On the SPDS I might just hack it and find a way of adapting normal contact switches there.

Maybe trying the silver paint like Tubetec discribed

Are the keys pressing a rubber button with a carbon contact?  If so, you can clean off the contact point and use a dot of foil tape to replace the carbon.

I tried the foil tape also, in my case pieces of copper tape.
The glue doesn't adhere well  to the rubber and although it works in the begging unfortunately the tape unglues itself after some usage...

Re: restoring vintage keyboards
« Reply #8 on: December 10, 2020, 02:23:09 PM »
Ive noticed sometimes the carbon contacts on the rubber gets a shine on it then it doesnt contact very well . In cases like that I found  like Walter said ,a very gentle rub with a pencil eraser or even very fine grit emery paper (600 or 1000), just enough to scuff up the surface makes it good again . The lower pcb contacts I found cotton buds with isopropyl work on , or in some cases like tv remotes where contamination is more of a problem , warm water , soap and an old toothbrush to scrub away any gunk is best, of course dry everything before powering up .

ward

Re: restoring vintage keyboards
« Reply #9 on: December 10, 2020, 03:22:52 PM »
I've cleaned both sides with isopropyl, and it helped ... but it didn't last.
I've ordered some silver paint and i'm gonna give that a chance.


Rob Flinn

Re: restoring vintage keyboards
« Reply #10 on: December 10, 2020, 04:53:03 PM »
Join this Facebook Group "Vintage Synth Repair And Mods".  There is a lot of information about this sort of thing there, & lots of people who are very experienced in restoring vintage synths .
regards Rob

Whoops

Re: restoring vintage keyboards
« Reply #11 on: December 10, 2020, 05:58:20 PM »
Join this Facebook Group "Vintage Synth Repair And Mods".  There is a lot of information about this sort of thing there, & lots of people who are very experienced in restoring vintage synths .

thanks for sharing Rob, that's nice to know

Re: restoring vintage keyboards
« Reply #12 on: December 10, 2020, 06:23:13 PM »
I'd avoid the silver conductive paint in this situation .
what I would try after iso and lightly scraping the surface of the carbon pad on the rubber side is adding a layer or two of electrical tape where the key contacts the upper surface of the rubber , a few tens of extra microns could make all the difference to the amount of the upper carbon pad(which has a convex shape) that hits the lower two contacts and therefore the pressure applied. If you exhaust that possibility I'd try and order new rubber sections . Although I did mention the silver loaded paint ,I only ever used than on much older keyboards without the rubber/carbon pads .

Whoops

Re: restoring vintage keyboards
« Reply #13 on: December 10, 2020, 06:27:07 PM »
If you exhaust that possibility I'd try and order new rubber sections .

Ordering new rubber sections, if available, is the best solution overall

ward

Re: restoring vintage keyboards
« Reply #14 on: December 11, 2020, 07:40:40 AM »
Hmmm, something else is off ...
The malfunctioning keys come in groups of 5.

I gotta dive back into the manual I guess
http://www.houseofsynth.com/hos-downloads/manuals/Roland/Roland-Service-Manuals/Roland-D-70-Service-Notes.pdf

ward

Re: restoring vintage keyboards
« Reply #15 on: December 11, 2020, 08:56:47 AM »
Found it, it's the dreaded flexible connector between keybed and motherboard.
If I put some pressure on the plastic retainer every key works.
I've seen some pretty messy repairs on the web with flat cable.
I hope I can fix it with the liquid silver glue.


 

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