Rescuing your old VIC keyboard

[eslapion]

As I mentioned in another message, I recently got my hands on a VIC20 of the very first batches. One made, according to the date codes on the chips, around mid 1981.

However when it got to me, most of the keys on the keyboard were very much unresponsive, needing impacts akeen to that of a hammer to let something come up on screen.

I meticulously cleaned the keyboard after removing it from the casing and disconnecting it. I even opened up the thing and removed all 20 little screws and cleaned every single keys contacts but the improvement was not very significant.

Then I was suggested by a friend to try and use a rubber keypad repair kit. (see www.digikey.ca and type CW2605 in the parts search field)

All VIC20 keyboards use internally a piece of carbonated rubber that contacts with one (for the older models) or two (for the all other VICs and the 64) gold plated tabs.

With a single kit I was able to treat the carbonated rubbers of all 64 keys of two keyboards, the keyboard of my old VIC and that of my 64. It was a long and tedious job and I had to hurry because if you wait too long, the stuff will begin to cure and will become impossible to spread on the tiny pads.

After waiting for a full day to let the product cure completely, I began testing the keyboards AND THEY WORKED BETTER THAN NEW. Even brand new keyboards were not as sensitive as these.

Chemtronics is the only company that I know who makes this sort of product but apparently MG is also coming up with a similar product.

[carlsson]

On comp.sys.cbm, it was mentioned a graphite spray (at least available in Germany). I suppose it fills the same purpose as the product you mention. In theory, a soft graphite pencil should work reasonably well, but I don't quite know. My clicky VIC keyboard worked fine by just cleaning it, but one or two keys on a recent PET keyboard didn't improve by rubbing a pencil against the rubber. I had to swap rubber plungers to some keys that are less required to get the most important ones to work. Maybe a spray product would make a difference.

[Boray]

I think I used just water and some soap on mine. And isopropanol on the metal.

[eslapion]

On comp.sys.cbm, it was mentioned a graphite spray (at least available in Germany). I suppose it fills the same purpose as the product you mention. In theory, a soft graphite pencil should work reasonably well, but I don't quite know. My clicky VIC keyboard worked fine by just cleaning it, but one or two keys on a recent PET keyboard didn't improve by rubbing a pencil against the rubber. I had to swap rubber plungers to some keys that are less required to get the most important ones to work. Maybe a spray product would make a difference.

Graphite is, I think, not a good idea because it can cause carbon build-ups on the gold plated pads in the long run.

This product's effect is possible because it contains silver which will not build up carbon.

Also, this is not a spray product. This is a mix and let cure type of coating you apply with a very small brush. I am certain it would resolve your faulty PET keys problem however, once mixed, this thing will cure and you will lose the rest of the batch if you only have a small number of keys to fix.

[eslapion]

I think I used just water and some soap on mine. And isopropanol on the metal.

That's the way I cleaned up my old VIC keyboard in the first place. It did improve but not nearly as much as with the repair kit.

[carlsson]

Tonight, I took apart the keyboard from my (big brothers) first C64, a breadbox bought second-hand in 1985-86. It has had quite a lot of wear over the years, and call it sluggish would be flattering.

For a while, it has been sitting in a broken VIC-20 (!) while the keyboard from the broken VIC-20 has been sitting in the original broken C64. To the point is that one of the plastic pins on the VIC keyboard is broken, so that keyboard is lacking one key, at the moment F7/F8.

Anyway, I took the standard procedure. Remove all the back screws, separate the board from the keys. Desolder the Shift Lock mechanism. Pry away the keys one by one and put the keycaps in a bowl of dishwater. Maintain the springs and rubber plungers (although one spring must've come loose). Let keys soak in the dishwater, scrub the plastic board with soap and water, rinse off in the shower. Then I rubbed R/W head cleaning liquid (basically isopropanol I believe) over all the contact edges on the board, and got rid of some old dirt.

I had a quick look at the rubber, but I hoped it would be fine. So I reassembled it all again, put in a few screws and tested. Perfect, almost like new again! Soldered back the Shift Lock, put in the rest of the small screws and wow, a 20+ year old keyboard that has been used a lot, about as responsive as when it was new.

I know we previously discussed the difference between VIC-20 and C64 keyboards. While they physically and electronically are interchangeable, internally they must be different. I can't remember how the Shift and Restore keys look like on a VIC keyboard, but the C64 keys had two locations to fit the plastic pin, of which only one was suitable. Ditto for the function keys, and here I had a brown VIC function key to compare with. The VIC keys has one pin hole in the middle, but the C64 keys have two on either side of the middle. It means in order to put grey function keys in a VIC-20 (or brown in a C64), one probably have to exchange the whole keyboard instead of single keycaps. However, I know there are at least two, maybe more different types of VIC-20 keyboard mechanisms, and the latter (CR) may be modelled exactly like the C64 keyboards, so it would only be some very early VIC keyboard where the keycaps are not "compatible".

[eslapion]

I know we previously discussed the difference between VIC-20 and C64 keyboards. While they physically and electronically are interchangeable, internally they must be different.

The VIC CR's keyboard is identical to that of the 64.

I know of 3 different types of keyboards for the VIC:

The oldest one uses very squarish keys and is identical to what you see on the cover of the Programmer's reference guide. It is with this type of keyboard that the rubber keypad repair kit has the most usefulness. If a smoker has used the computer for a while tar penetrates the contact pads and just ruins the tiny cabonated rubber pad. If water or any trace liquids have entered the keyboard, the rubber seems to get "dissolved" by bacterias. Considering there are two columns of holes being covered by black electric tape, I believe this is some sort of modified PET keyboard and therefore a lot of PET keyboard must suffer similar problems

The second one is externally identical to the VIC CRs with roundish keys but internally uses the same PCB as the older keyboard with NO SPRINGS and some weird succion pad style contacts. Mostly found on later generations of VICs with 2 pin power supplies of smaller size. The repair kit is less useful here because the succion pads completely "seal" both the black rubber and the contact on the PCB.

The third one is the VIC CRs and this one is internally identical to that of a 64 with large 2-contacts carbonated rubber pads. With 2 gold plated contacts and a large piece of black rubber, these keyboard seems to resist pretty much anything you throw at them. Cleaning with isopropyl alccol seems to always do the trick with this one.

[PaulQ]

I've always used rubbing alcohol myself to clean electronic contacts, with great success. When I get around to disassembling my keyboard, that's what I'll use; I'll post the results on that later.

[PaulQ]

I finally got around to cleaning my keyboard today (the C64 one); good old rubbing alcohol did the trick:



I also cleaned the rubberized carbon contacts.



While I had it apart, I decided to photograph the motherboard:



Just like me, it was made in Canada: