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clh333
March 26th, 2017, 01:17 PM
I fired up the Kaypro II this afternoon and could only find the CP/M 2.2 Master disk to boot with so I thought I should make a working copy before doing anything else. I found a suitable DD for a target and started to type COPY at the terminal, but got only as far as CO... Rats! dead key.

Went and got the keyboard from a Kaypro 4 and substituted that. This time I got as far as COP... No "Y"? What is this?

Long story made shorter, I took the II keyboard apart and cleaned out the shell, dusted the switch assembly, but also took the trace board off the key matrix. Looking carefully I could see that the P key's little silver contact pad was shorter (more sunken) than the ones around it. In fact it was shorter than the plastic key housing and was never going to make contact. With some fiddling I fashioned another pad out of some packing foam and put the keyboard back together. It works, although the pressure is noticeably different.

It appears this is a one-way street, with deterioration the destination. I'm wondering if anyone else has run across this problem and if so how they solved it. Are there any replacement pads with foils available anywhere, for instance?

Thanks for your suggestions.

-CH-

Stone
March 26th, 2017, 01:25 PM
I don't do CP/M but I know in DOS you can simulate any key with the ALT key + three numbers on the numeric keypad. So no key need ever be dead. :-)

KC9UDX
March 26th, 2017, 01:40 PM
Isn't that a function of the IBM BIOS? The Kaypro II will not do that.

I've not had mine apart to know what it looks like, but I've heard of similar problems with other keyboards. So I'm sure there's a good solution; but unfortunately I couldn't give you any details.

SomeGuy
March 26th, 2017, 01:40 PM
These Keytronic capacitive keyboards were used in a number of systems. Search the forums for Compaq Portable keyboard repair. There a number of threads here about those. I don't have the link off hand, but there is a seller on eBay that sells replacement foam pads, but you will need to keep and re-use the silver disks and the rigid plastic disks that hold the pad in (double check that your keyboard use the same size pad). Note that the exposed side of the foil is NOT CONDUCTIVE, each key acts as a capacitor rather than an electrical switch, hence why they are called capacitive keyboards.

In time ALL of these types of keyboards will need the pads replaced.

One little hint, due to static the foil disks will jump as you try to attach them to the new pads. You can dampen the surface the disk is resting on or use a post-it note to help hold it in place. A magnifying glass helps loads too.

Bungo Pony
March 26th, 2017, 02:26 PM
I painstakingly re-did all of the keys on my Kaypro II. Took me about two weeks, but I did it for under $10. I put pictures and instructions here:

http://www.classicalgasemissions.com/2016/04/restoring-kaypro-ii-computer.html

Stone
March 26th, 2017, 02:55 PM
Isn't that a function of the IBM BIOS?I wouldn't think so since it works on machines without an IBM BIOS and that includes later Windows versions.

http://www.irongeek.com/alt-numpad-ascii-key-combos-and-chart.html

So it has nothing to do with the IBM BIOS.

KC9UDX
March 26th, 2017, 07:04 PM
I wouldn't think so since it works on machines without an IBM BIOS and that includes later Windows versions.

http://www.irongeek.com/alt-numpad-ascii-key-combos-and-chart.html

So it has nothing to do with the IBM BIOS.

Perhaps you should correct Wikipedia then.
https://en.m.wikipedia.org/wiki/Alt_code

As useful as I always thought that was, it's nowhere as useful as being able to type foreign language characters on the standard QWERTY Amiga keyboard, or being able to fully control the mouse via that keyboard. :)

deramp5113
March 26th, 2017, 07:24 PM
Replacement foam pads for these keyboards are not easy to make, though many hobbyists have done so.

Some of these pads are occasionally available on eBay. Presently see http://www.ebay.com/itm/Apple-Lisa-Keyboard-Capacitive-Pads-OEM-Factory-Made-Not-Home-Made-/201757081882?hash=item2ef9a8c11a:g:ywgAAOSwBP9UYiu o
and http://www.ebay.com/itm/1-Set-of-100-Foam-Capacitive-Pads-for-Vintage-KeyTronic-Style-Keyboard-Repair-/272602057361?hash=item3f78594a91:g:KXwAAOSwXYtY1B7 n

I have gone the following route with great sucess: Sun Type 4 keyboards use a newer version of the same pad that does not seem to break down nearly as fast as in the older keyboards. As of 2017, Sun type 4 keyboards are still available on the Internet. A search under the part numbers, 320-1005 and 320-1018, yields results for the Sun Type 4 keyboard. This is not the official model number, but may be a Sun internal part number (the number is present on the product label, but it’s meaning is not identified). The 1018 number is a “French Canadian” keyboard. It seems to be the most readily available. These show up on numerous websites for around $20-$30. I have purchased three of these keyboards and they have all been received in brand-new like condition and the pads have all been in excellent condition.

I have found that even after replacing all pads, some keys still just don't want to work. Using a fine grit sandpaper (e.g., 600) and gently sanding the PCB surface to remove all oxidation from the PCB “capacitor” pads has eliminated these problems.

Mike

SomeGuy
March 26th, 2017, 09:12 PM
Here is the seller with the pads you have to add your own disks to:
http://www.ebay.com/itm/Victor-9000-SIRIUS-1-Keyboard-repair-Foam-Pads-for-KeyTronic-Keyboards-/121266887970#ht_2315wt_989

But if complete assembled pads are available then those are obviously much easier.

JonB
March 27th, 2017, 05:44 AM
There is even a video up on youtube showing the repair of a Keytronic keyboard that came with the Tandy TRS-80 Model 16B

https://www.youtube.com/watch?v=TvFcr03g-j0

..by Ian Mavric who is a prominent and highly regarded member of the TRS-80 community. This is a great vid that gives you some indication of the amount of work that's necessary. However don't be too put off, it gets easier once you have done a few of them. The only comment I'd make is I think you shouldn't use a screwdriver to hold the mylar disk when cleaning it because there's a greater risk of damage. Instead, use a cotton bud to hold one end, then use a second bud to remove the gunk. I actually soak them in meths to loosen the gunk first.

Sadly, the Keytronic keyboards all deteriorate like this. The foam disintegrates over time. Being capacitative, the foil disk doesn't need to actually make contact with the PCB in order to register a keystroke; it just needs to get near enough to induce a capacitance between the tracks. Anyway, the point I'm trying to make is that you are likely to find yourself repairing more keys as time goes by, and maybe you should take the plunge and do them all at the same time.

Repairing them is worth it, though, as they have a lovely feel to them.

clh333
March 27th, 2017, 07:22 AM
Thanks to all who replied. It's comforting to know you're not alone in this.

The foam is that soft-spongy foam that was ubiquitous in the '80s; I have printers for example which are lined with foam that is in the same shape. I don't know if deterioration over time is inevitable or if modern chemistry has improved on that tendency. I do know the foam I used is too stiff.

I have four Kaypros and each has bout 75 keys so that's 300 little pads to repair. I'll probably wind up doing a little experimentation to find the right materials and techniques. My one-off was okay for emergencies but not-ready-for-prime-time, so to speak.

I Googled the topic and came up with a post from 2011 on the VCF: http://www.vcfed.org/forum/showthread.php?15602-Keytronic-Keyboard-Repair-foil-discs. Two gents named David Schmidt and Geoff Harrison were involved in that discussion. I like their ideas of using anti-static bags for foils and making a sandwich of foil and foam before punching out the dots.

Thirty-five cents for a bare foam dot is a little pricey, especially if you have to buy 100 of them before you can see if they will work or how they feel. I'm going to pass on the eBay sellers. I looked for a Sun type 4 keyboard; there was one and it was going for $40. Saving that for plan B.

Unfortunately there is no ALT key on the Kaypro keyboard. Everything in CP/M-land is CONTROL-this and CONTROL-that. First time I saw an IBM keyboard I was wondering what the ALT key was used for.

I'll let you know how I progress. Thanks again for your replies.

-CH-

deramp5113
March 27th, 2017, 08:54 AM
If interested, here's the Sun type 4 keyboard for $24.98 plus shipping: http://www.memoryxsun.com/3201018.html

Mike

KC9UDX
March 27th, 2017, 10:51 AM
@clh333:

That foam was invented to sell k7s! It was what made Stereo 8 bad.

I'm still trying to wrap my head around my PET and it's lack of a Control key.

clh333
March 27th, 2017, 11:20 AM
I called KeyTronic today and inquired about replacement foam and foil pads. I was told that they discontinued the board twenty years ago; they kept replacement pads for five years for warranty purposes but ran out shortly thereafter. I asked if there were specs for the pads' foam or foil. The lady told me she had looked for them once but they were gone, too. However, she did know that a company called DeccoFelt made them; that KeyTronic purchased them from DeccoFelt.

Well, it happens that there is still a company in Los Angeles called DeccoFelt and they make products for the electronics industry, among other things. I made inquiry by email to see if they could furnish replacements. I doubt they will but they may be able to tell me what materials were used and maybe their sources.

Worth a shot...

-CH-

JonB
March 29th, 2017, 10:46 PM
There's more than one way to skin this particular cat. You can buy the pads much more cheaply in bulk.

For example:

http://www.ebay.co.uk/itm/121266887970

and

http://www.ebay.co.uk/itm/272602057361

JonB
March 29th, 2017, 10:57 PM
@clh333:

That foam was invented to sell k7s! It was what made Stereo 8 bad.

I'm still trying to wrap my head around my PET and it's lack of a Control key.

What's a K7?

KC9UDX
March 30th, 2017, 12:15 AM
What's a K7?

http://www.getuncommon.com/images/products/images/0038_6_I/thumbs/480_Tape.jpg

JonB
March 30th, 2017, 01:13 AM
Ah. "Compact Cassette".

Stereo8 failed for more than the foam by the way. I read the Wikipedia article on it, interesting..

KC9UDX
March 30th, 2017, 01:33 AM
Stereo8 failed for more than the foam by the way. I read the Wikipedia article on it, interesting..
The biggest reason for the demise was greatly cheapened quality. Foam was a big part of that. Metal springs which pushed the tape against the tape head were replaced with foam which would deteriorate, causing very bad sound quality.

JonB
March 30th, 2017, 02:47 AM
The biggest reason for the demise was greatly cheapened quality. Foam was a big part of that. Metal springs which pushed the tape against the tape head were replaced with foam which would deteriorate, causing very bad sound quality.

Yes, that was it. And replacing the rubber capstan with a plastic one.. Now it is interesting about this foam pad. The Sinclair Microdrives use the same sort of stuff, and deteriorate just like the Keytronic pads. People recondition them using felt pads similar to what you find in Compact Cassettes, but these fall apart quickly due to tape speed and friction and you get fibres inside the sealed cases. A Microdrive is like an 8 track cartridge (endless tape loop) but in miniature - they are the size of a postage stamp.