1200XL Keyboard

[Lumpy01]

So, I recently aquired a 1200XL to sit next to my modded 800XL. I've wanted one ever since they were first released, but never managed to get my hands on one until today. The keyboard was acting a little flaky so I visited Best Electronics and requested a replacement. To my dismay, they informed me that after 28 years of carrying 1200XL replacement keyboards, they no longer have them in stock. What a bummer!

 

I know I could take the existing kayboard apart and clean it as documented on the RetroBits website, but I'd rather replace it with a nice new OEM keyboard. Since Best Electronics is no longer an option, does anybody know where else I could procure a replacement?

 

Many Thanks!

 

Paul

 

 

[Kyle22]

If you find a source, please let us all know.

[Bryan]

The keyboard was fatally flawed and even a replacement is only a temporary fix. What is needed is a new PCB/switch assembly which can be attached to the existing frame. I got tired of fixing keyboards and eventually sold off all my 1200XL's.

[ACML]

I just sold one last week. If you are inclined and you are willing to spend a couple hours fixing your existing keyboard, it is not too difficult. Basically the carbon (conductive) traces that touch the PCB have oxidized and no longer have continuity. You can buy "Bare Paint" for $10 at Radioshack which is a conductive paint just as good as the circutwriter pen. Actually, I like it better because it is thicker paint and I apply it with a toothpick.

 

1) The tricky part of the whole process, is separating the white silicon spacer gasket from the PCB.

2) Go slow, yes it will tear, but if you take your time you can peel it back.

3) When it tears, just free it locally from the sticky point and lay it back in place.

4) Leave the white spacer attached to the mylar sheet.

5) The tears won't effect its performance as long as you lay them back in their original position.

6) Remember to remove and discard the tape looking separator between PCB to mylar trace connection point.

7) If you have an multimeter, you can start on each terminal position on the mylar, follow it to each pad and check continuity. This will identify breaks in the trace.

Troubleshoot the trace with the multimeter to find the actual break location.

9) if the white silicon spacer is covering it, you need to gently peel it back, tearing is O.K. and apply some conductive paint on the trace.

10) Important: Let it air dray for 30 minutes (hair drying will speed this up). Even though the multimeter still doesn't show continuity, the Bare Paint will work.

11) Make sure you touch up all the terminal ends on the mylar traces where they will touch the PCB pads.

12) Let dry, assemble and test.

13) If a particular single key in the string is still intermittent. the Pad should be cleaned with 90% isoprop alcohol.

14) more than one key is still non-functional on the same string, you have missed a break in that trace. Disassemble and trouble shoot that line. Yes, its like fixing Christmas lights. This is where it was important to let it dry completely before you assemble because now when you take it back apart (it will be much easier this time), it won't stick to the silicon space and break the traces you already repaired.

 

Sounds like a lot, but if you take care separating the mylar/silicon from the PCB, it won't have too many breaks.

 

P.S. I bought the second to last 1200XL keyboard from Best back in June.

 

Good luck!

Edited November 29, 2013 by ACML

[+bob1200xl]

I have brand new keyboards, still in the box. None of them work. I have fixed many of them that have now been working properly for 5 years or more.

 

It is a PITA, but doable. The silicone separator normally sticks at the screw holes, where you need to take extra care. I don't think I've ever done one that didn't tear. I don't think it ever mattered that it did - just put the pieces back in place.

 

Do NOT try heating the silicone.

 

Re-paint all of the board contact fingers - carefully - not needed on the key contacts.

 

You can clean the gold key contacts with alcohol, but if you get too aggressive on the mylar contacts with it, it will dissolve them.

 

Sometimes, it seems to help if you drill out the alignment pin holes (just a little) and shift the position of the PCB. This compensates for wear on the key contacts, I think.

 

Bob

 

 

I usually work on new keyboards which have no wear on them, so the only failure point is the contact fingers that conduct the signals from the mylar to the PCB. Keyboards with lots or wear usually need the gold key contacts cleaned and, not often, the mylar key contacts cleaned.

[Panther]

It all sounds worse than it is really. Worked out great for me.

[Kyle22]

Hi Bob,

 

I'm just dreaming now, but, if I happened to win the Lotto, I asked Mitsumi to make more keyboards for my 1200XL/1400XL/1450XLD project... What do you think it would cost?

 

 

-K

[Lumpy01]

Well, I guess I'll try my hand at rehabing the old one. Thanks for the help.

 

Kyle - Lemme know when you win that lottery and get those keyboards made. I'll happily be your first customer!

[ACML]

Well, I guess I'll try my hand at rehabing the old one. Thanks for the help.

 

Kyle - Lemme know when you win that lottery and get those keyboards made. I'll happily be your first customer!

Let me leave you one more tip. It is quite possible that you will find no breaks in the traces during your continuity check. That being, the multimeter can't kind any dis-continuity (an open). This is actually great. This usually just means you have to touch up the terminal pads that make contact with the gold plated terminal points on the PCB (remember to remove and discard the thin piece of tape covering the gold contacts on the PCB side. After you touch up the terminals on the mylar, allow the paint to dry, check to make sure you don't have a short between traces at the terminal block you just touched up. If I remember correctly, on one end there is the last two terminal points that should show continuity (short) because they are supposed to (follow the traces and you'll see they are supposed to connect. One more thing, when you test it the BREAK key will not register on the keyboard self test. It has it's own unique interrupt and its the only key that does not register on the self test. Fooled me the first time. You can verify the BREAK key is working by popping in BASIC, type a line of text and before you hit RETURN, hit the BREAK key. It should abort your line entry and return the cursor to column 3 of the next line. If you hit it again and again, it will keep moving the cursor down the screen (carriage return for us old folks).

Edited November 30, 2013 by ACML