Useful overview of a very real issue for vintage computer restoration projects.

Thanks for finding a product that works and passing the link on. I've got a few different conductive glues/paints and they're all pretty bad at sticking to flexible surfaces.

Next level stuff with your test fixture ! I repair old synthesizers, and key contact strips are getting hard to find. I'll try some of your tips. Thanks !

Thanks Jeff!

thanks, great advices. I am into a project attempting to recreate an atari keyboard based on conductive rubber domes. Quite hard to do it consistently. Will try these replacement pads.

Great video! I think the conductive Nickel ink pen I use is MG Chemicals. It was pretty expensive but it works super well - resistance is less than 100 ohms for most applications I've done.

Thanks for sharing. I'm repairing a lot of those rubber pads in synthesizer keyboards and a lot of vintage electronics I refurbish. But i'm still disappointed by all solutions I tried and you showed me those pens I didn't know about. If at some point I find something new I'll be bacl to you. And yeah, very funny CNC pen shaking 😂 I managed something similar do dip my painting brishes in a buck of solvent to clean them. Bye.

@HeyBirt

3 жыл бұрын

If it is a case of the conductive coating wearing off the pens do a great job. I have found other typed of conductive rubber develop a high resistance due to contamination. I did find a way to rejuvenate them though kzread.info/dash/bejne/oG2bqdxrnpDZcrg.html

Very interesting experiments. Wondering if a solvent soak/agitation could purge the oils from the keyboard contacts and allow for a better application?

@HeyBirt

4 жыл бұрын

That would be something to try. the conductive paint has a high resistance until it is dry, I think the solvent keeps the carbon particles separated. So, if the grease contamination has the same effect and it could be cleaned them it might help. I wonder though if the grease has some permanent chemical effect on the rubber.

@waynesallee-com

Жыл бұрын

That's what I was thinking. Rubber O Rings that get contaminated with oil will swell, and become too large to use. Soaking them in alcohol for a few minutes shrinks them back down quickly to proper size. So this trick might also help with conductive rubber pads. I have used oil to swell rubber o rings so that they seal tighter, knowing that I will not be able to get the product back together if I take it apart, but knowing that the alcohol bath fixes that problem. Communist Google will shadow-ban this post.

Recently i was working on my wireless membrane keypad, that time i come across conductive ink and pen, both are costly for home use. I come to knew that we can make conductive ink from grafite powder.u uses pensil grafite powder and glue.it works ,but problem was track of membrane was broken at connector.so it was not easy to draw track.but it is possible.now i come again with new problem ,wireless walkie talkie lcd/ key pad problem, may be either. Ones i have cleaned the rubber carbon with pcb cleaner .my question is will that cleaner damaged the rubber back coating ?

Ive found wiping a bit of graphite onto the rubber works too

@HeyBirt

3 жыл бұрын

Thanks Stan. Someone else told me this and I did some testing with graphite in a more recent video. It seems a very thin layer of graphite has a high resistance. I am guessing that the improvement may have come from slightly abrading the rubber whilst rubbing the graphite on. This would tend to remove any surface oxidation. I built a test jig for precisely measuring contact resistance of C64/C128/Amiga Mitsumi keys which allowed for good measurements. kzread.info/dash/bejne/oG2bqdxrnpDZcrg.html

Hey Birt!, Now that it is a couple years ago, how did this repair hold up ? How would it go with e.g. TV remote that gets couple hours / day ?

@HeyBirt

2 жыл бұрын

The keypad from the 3D printers still work fine. I also recently did an audio editing machine keypad for a friend and found the kit I had used was no longer available and the conductive ink part had dried up. I used the super glue primer, some good quality super glue and CaiKot which worked just as well and all of these items are easy to find.

Hello, I have a 2006 Sundance Spa Capri and it’s topside control panel for the jet has stopped working I have placed jumpers to fool the system to thinking it’s freezing which the heater turns on and the pump goes to the low mode. All other buttons on the membrane works. The unit costs over $500 which I would hate to purchase for this one issue. I was thinking about cutting a circle around the worn button then clean the area and reinstall the removed cutout and seal it. Or I hope that all Spas circuit boards are similar and it could place any panel on top so that I can get the jets to work. I have basic knowledge of electronics but my family doesn’t. Have you ever repaired a spa panel? If so please make a video.

@HeyBirt

4 жыл бұрын

I have not worked on a Spa control board before. If it is just the conductive rubber on the button that is work you may be able to fix that. Sometimes a thin plastic membrane with conductive traces printed on it is used. Sometimes these can be fixed and sometimes not. You would have to take the unit apart to see how it is constructed to get an idea of how it might be repaired.

I need a little help here. Any suggestion if the carbon contacts were damaged by a fluid spill? I have a keyboard (piano) with one broken key. I opened it and found out that theres a liquid spill, I cleaned it with a piece of cloth and the carbon contact just came out easily. I wish to repair this keyboard in our church. Maybe you have a great idea?

@HeyBirt

4 жыл бұрын

Is it the key contact itself that come off or a piece of a trace leading to it?

@SIRAYEH

4 жыл бұрын

Its the black carbon printed on the pcb that went off easily. Not the rubber ones. Any idea?

@HeyBirt

4 жыл бұрын

I tired a product called 'KeyPad-Fix' (keypadfix dot com) which is sort of a carbon impregnated adhesive. I found it was too brittle to recoat the rubber buttons but I suspect it would work for replacing the carbon contact or small part of carbon trace on the PCB.

Could I use Krazy Super Glue to repair the torn apart silicone rubber pads?

@HeyBirt

3 ай бұрын

CA (super glue) dies seem to stick well to clean silicone rubber. Not sure how it would work long term for gluing torn pads but it is worth trying it out.

Bro were we get this rubbers

@HeyBirt

2 жыл бұрын

I did this video 2.5 years ago so I'm not sure what 'rubber' you are referring to.

I used the CaliKote 44 stuff on the keypad for an in-house pager system where one button was worn out (the one you end up pressing no matter who you page). Each time I’d repair it, it would work gloriously until the next person mashed that button extra hard out of habit. That would cause the coating to flake and short the key, which prevented it from registering any other key. Eventually I gave up. The biggest issue was that the carbon impregnated part was more of a thin walled ring where the walls of the ring would deform when the button was pressed… which obviously isn’t going to work with any coating that can flake off. As for the Makerbot thing at 14:30, I would’ve used a hole punch and aluminum or copper tape. I often do this for Atari 5200 controllers and it works great. It may seem like the tape doesn’t stick too well but it does if you use the back of a pen or something to smash it REALLY flat. I use the hole punches that are smaller than standard (eighth inch?).

@HeyBirt

2 жыл бұрын

Yes, you can't use a paint on coating for conductive rubber that flexes a lot like I showed on the Amiga key stems. The Makerbot keypads are still working fine years later. I used the same technique to a BOSS music thing for a friend using regular superglue and CaiKote and it is still working fine too. The pretreatment with superglue is essential. The glue sticks to the rubber and the paint sticks to the glue.

How do you put together a broken carbon contact that broke along a crack in a PCB for a MIDI keyboard?

@HeyBirt

2 жыл бұрын

Are you asking about fixing a broken carbon trace? If so you can get a carbon repair pen (like carbon paint in a pen). I have also used a project called 'CaiKote' for this.

@myvid222

2 жыл бұрын

@@HeyBirt The problem is that there is a gap in the PCB that needs to be bridged. Applying a layer of conductive silver does not do that.

@HeyBirt

2 жыл бұрын

@@myvid222 Since I can't see the board don't know what to suggest. How big is the gap? Is there a hole in the PCB, etc.

@myvid222

2 жыл бұрын

@@HeyBirt Here is a link to the picture: www.reddit.com/r/ElectronicsRepair/comments/p2u4rk/how_can_broken_contact_points_in_a_midi_keyboard/ . The PCB was broken and then pressed back in, without any missing pieces, but the traces and contacts intersecting with the cracks needed to be reconnected.

@HeyBirt

2 жыл бұрын

@@myvid222 Those are carbon printed button contacts. The black part on the bottom of the button rubber is carbon infused rubber (called carbon pill). When you press the button down it bridges the interlocking carbon printed 'fingers', which completes the circuit. You can paint the missing printed carbon traces back on with a carbon pen.

I never understood why they used rubber pads, as rubber is non conductive. I thought they used some kind of carbon solution on the tip of the pads to give them conductivity?

@HeyBirt

4 жыл бұрын

The 'carbon pill', the back rubber that is the contact is actually conductive. It is a mixture of silicone rubber and carbon. There is enough carbon to make the rubber fairly conductive. On the cheap keypads, like the MakerBot one, the conductive rubber layer is very thin. On similar keypads you will often see that this conductive layer is about 0.5mm thick.

@lifeschool

4 жыл бұрын

@@HeyBirt - Thanks! :)

@doktor6495

4 жыл бұрын

Hi lifeschool. You need the rubber to have a haptic feedback when pressing the key. Best greetings, Doc64!

Free tip for everyone I used to repair remote control pads with regular battery carbon. How? I open a regular carbon AA or AAA battery (dead or new, doesn't matter) with a knife. Then I apply a thin coat of battery carbon on the damaged (or not working) rubber pad (the black part). Clean the excess in order to leave only a small thin layer Test it, it should work. This came as a surprise to me how well the battery carbon sticks to the rubber pads, its really hard to remove it, therefore, its a great free instant fix for rubber pad contact problems. Replacing the whole pad is better, but you can't beat this fix, as it requires no ordering nor any special products or tools other than a dead AA battery.

@nothingstellar

3 жыл бұрын

this sounds pretty dangerous tho

@HeyBirt

3 жыл бұрын

You can also use graphite powder. It does help improve conductivity enough that if the pad is marginal it will work. For ones that are really worn out it does not help (in my experience.)

@lmp2208

2 жыл бұрын

Are you saying the battery carbon has some sticky substance included. If repairing a remote that is used 2 hrs / day, how long would this fix last ?

MG Chemicals has horrible ratings (23% one-star) on Amazon. Furthermore, it is out of stock. Have you tried Keypad-Fix? Overall, nothing works flawlessly. Not even Caikot 44. Most elastomeric conductive rubber deteriorates over time. Blame it on ozone layer depletion and corrosive substances in the air. In my locality, rubber literally melts over time.

@HeyBirt

3 жыл бұрын

I place no faith in amazon ratings. MG Chemicals has been in business for many years and makes good products. I found out a few weeks ago that MG Chemicals has obsoleted this product. This caused me to realize that all the component parts are readily available from other sources. The super glue primer is available from many places as is super glue. These two items act as an interface layer for the conductive coating to stick to. Then you just need a good conductive coating. I fixed a BOSS keypad for a friend using the primer left over from the MG kit with a good brand of super glue I had on hand. I then coated this with CaiKot 44 and let it sit a couple of days. This worked fine but we will have to see how long it lasts. For thick conductive rubber you can rejuvenate it easily. Search my other videos for "Resistance is futile"

@alohamark3025

3 жыл бұрын

@@HeyBirt Thanks for the tips. I have a dozen remotes ruined by Duracell batteries. One was a clock that runs 24/7. Even if you check it every month, the battery can still leak in between the checks. Their warranty is B.S. Anyway, there are a lot of carbon elastomeric pads on Ebay, but finding the best one is not easy. Like you, I own a lot of vintage musical gear. Fixing old Casio devices is the most aggravating job I've ever run across.