Problems with rubber/contacts (, was: D70 / Roland repair)

[bert mouwen]

Eric Barbour wrote:
> 
> > Possible reason:  All the rubber thingies were made at the same time
> > (i.e. 11 or so years ago)

A few month ago this item passed already - i'm sure Martin Czech knows
this as well, but as a reminder i will list her some excerpts
from reactions in that thread. I know i'm creating redundancy here,
but as i have no webpage of my own, i had to post it.
If someone recognises a method and has some additional experience
or knowledge, let us know?

Before that i would like to add a last suggestion, a tip i got from a
technician on an official service-site:
He told me the best solution was WL-contactspray. (ever heard of?)
After a hot discussion about WD40 for sliders not to long ago,
personally i don't dare to try it, anyone with experience or comments?
Seems to be rather expensive.

Then now the qoutes from a little while ago: ->
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Rob Hukin <robh at biols.susx.ac.uk>:

Your problem may not be that the contacts keep getting dirty as much as
the conductive layer on the rubber is gradually deteriorating. I find
that cleaning only really works the first couple of times.
The best thing i've found for refurbishing keyboard rubber contact
strips is some stuff called Circuit Works Rubber Keypad Repair kit.
It's a 'two part carbon/silver coating that cures to form a tough,
flexible, wear resistant surface which provides excellent adhesion and
electrical conductivity...Tesing has shown repairs can withstand
over 500000 simulated keystrokes' (from the literature that comes with
it). It's quite expensive (about 20ukp for a kit) and rather
irritatingly comes in two sets of two-part mixtures that have to be
mixed all in one go, and will only stay usable for 72 hours (less in
my experience), so make sure you have plenty to do to make it
economical. It's made by a company called
Chemtronics Inc, Kennesaw, GA 30152-4370 USA, 800-645-5244.
I've used it on an HR-16, MMT-8 and my OB8 and it seems to work pretty
well.
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Per.Mattsson at mkv.mh.se:
I've fixed the buttons on a Alesis MMT-8. I made a fine =raphitepowder
by scratching arazorblade against a pencil. Then I took some of the
powder and - using a finger - rubbed it against the conductive rubber
surface on the buttons. It worked great, never had any problems with
that unit again.
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Johan Gustavsson moxie at idonex.se>:
Yep...I've found a somewhat cheaper way to go than that two-component
thingy, though. Electrolube silver conductive paint, for repairing
PCBs. I've sucessfully fixed a HR-16 with it, using only a small part
of the 3 gram contents, and it is still liquid some months
later. Don't know if it is as tough, though. It isn't cheap, either,
but you don't have to throw away what you don't use.
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Andrew Schrock <aschrock at cs.brandeis.edu>:
Eww! Ditch those pads ASAP. The problem is just oxidation of the metal
pad and dust getting trapped on or between the surface and the rubber
pads.
On my mmt-8, I replaced _all_ the buttons (something like 50 of them)
with low-profile tact switches. It works great now, and isn't "mushy"
anymore.
If you check hyperreal in the music machines section (under Alesis) I
seem to remember sending something over to them with the appropriate
mouser part numbers in it. It was around $20 for the switches, and I got
the mmt-8 used for $50... so that's an 8 track sequencer with tactile
switches and mute/unmutes for each track for $70. Not too bad. It is
somewhat of a pain to solder all the switches, but trust me, it's worth
it not to have the frustration of trying to mute something (esp. LIVE!)
and have the button "bounce" so it doesn't actually mute... or have the
play button "bounce"...
If you're really set on not replacing the switches, I've heard the
following works well, and gives a minimal amount of abrasion: Use fine
sandpaper to powder some graphite (rub a pencil against sandpaper).
Carefully collect the powder on the tip of a pencil eraser and _gently_
rub it against the metal contact. I would think that this method is a
little less severe than the razor blade method.
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tomg <tomg at vivid.net>:
I have done a lot of Rolands others (Korg & Kurzweil come to mind) have
the same problem but Rolands seem to be the worst. I don't know about
"THE" solution but a pencil eraser is my tool for carbon contacts. Just
enough rubbing to remove the gunk on the pad and contact. Then blow the
debre away with clean air. It works most of the time and when it works I
never get a return. If not Roland is usually very reasonable for
replacements. Most pads running in the $20 range and contacts costing
arround $15. (exceptions the JPX the costing about $90 for the pair and
if your RD-5000 is sick the whole kbd has to be replacd $400) I have
ordered jpx sets, juno and rhodes 660 contacts in the past two years.
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"Bill Layer" <b.layer at vikingelectronics.com>:
Conductive rubber switches are a major business in the telco industry;
several small companies stay busy doing nothing but repairing and
replacing these failure prone little devices. The ones that rely on
conductive paint are the worst, and can be quite prone to shorts.
A mail order company in Chicago IL, called Telecom Products has several
professional 'board-level' repair systems for these types of switches,
as well as cleaners, conditioners and plastic restorers. They also stock
obsolete parts, which could come in handy.
Telecom Products / Mike Sandman
804 Nerge Road
Roselle, IL 60172
630.980.7710
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