Atari 1200xl Keyboard Repairs

[_The Doctor__]

Yah keysystems , is punny, but keys/stems might be the ticket...

[+Stephen]

5 hours ago, bob1200xl said:

Yep. Millyions and millyions of 'em.

 

Bob

 

Sorry to derail - did you get my last email from almost a month ago now?  I needed info on where and how much cash to send your way.

[+bob1200xl]

You fell into the Black Hole... I'm on it again.  (I wondered what these disk caddies were doing in here)

 

Bob

[gosub_9]

Greetings, folks. ??

 

I'm brand new here. At the beginning of this year (2022), I pulled down my ATARI 1200XL off the shelf and made an attempt to bring it back to life. ?

 

After 36+ years in my parent's basement ⌛️ and a few years up in my closet, I finally got off my duff and purchased that 5-pin DIN to AV cable to get 'er hooked up to a monitor.

 

At first power-on? in nearly four decades, she came up like a champ: that beautiful "ATARI" rainbow that had achieved burn-in of heart of this 9 year old so many years ago.

 

Of course, most of you would be shocked if I said everything just worked. Of course not: the keyboard was utterly unresponsive. 

 

(...finally getting to my point...)

 

It was this thread that gave me the gumption ?? to crack that critter up and attempt to bring the keyboard back to life.

It took a couple of weekends, some hand-wringing, some courage (and a touch of stupidity) to get my childhood computer fully functioning.?

 

So, I wanted to say thank you all for having the public conversation/share that helped me envision what success might look like:

• @Dragonstomper — your detailed post at the beginning, here, gave me options. Having a choice helped me ease into the experience. I had hoped that increasing the k-value of all the springs woulda done it... in retrospect, I think I was always destined to life the mylar on this puppy. But I wouldn't have started with that kind of surgery and who knows if I would have abandoned the project.
• @bob1200xl — it was your counter-point post/response that helped built the creative tension in me that ultimate got me to reach for the hair-dryer (and *gasp* razor blade). 

Thank you, gentlemen.

 

I'm keeping a bit of journal as I go: https://sites.google.com/infosysengr.com/gosub9/list/10-help.

 

At first, I was on a mission to hook-up my childhood computer to the Internet  (i.e. build an SIO/Ethernet bridge; I've got some computer engineering and software development chops)... but then, as I started to explore this beautiful sub-culture of retro computing, I bumped into the Fujinet. ZOMG!

 

ANYWAY... thanks again for participating — it made for a welcoming space for me. ?

 

- John (aka GOSUB 9)

 

[_The Doctor__]

John is GOSUB 9 a reference to you going back to 9 years old when you got an Atari?

[gosub_9]

5 minutes ago, _The Doctor__ said:

John is GOSUB 9 a reference to you going back to 9 years old when you got an Atari?

It is.

 

Playing and learning on this computer was one of the most formative experiences of my life.

Dipping back there, knowing what I know now, is a rare treat. I GOSUB as often as I can.

[+bob1200xl]

Good job, gosub_9!

 

Anything you need, ask...

 

Bob

 

[hueyjones70]

I have found that once you take the screws out of the keyboard PCB, if you will drench a Q tip with alcohol and dab some on each screw hole that the rubber sheet comes off much easier.

[+bob1200xl]

Fantastic!

 

I have to try this. If you can release the screw holes, it makes it all easy.

 

Bob

 

[hueyjones70]

I bought a conductive paint pin at least three years ago and I am still using it. It is a BUDDY PAINT pin that uses silver, nickle, and copper. It has been discontinued and it received mediocre reviews but the longevity is great and i have used it to repair keyboards (800xl and 1200xl); repairing traces and repainting dots. I have also used it to repair some motherboards, but I always followed those repairs with wire.

[Beeblebrox]

4 minutes ago, hueyjones70 said:

I bought a conductive paint pin at least three years ago and I am still using it. It is a BUDDY PAINT pin that uses silver, nickle, and copper. It has been discontinued and it received mediocre reviews but the longevity is great and i have used it to repair keyboards (800xl and 1200xl); repairing traces and repainting dots. I have also used it to repair some motherboards, but I always followed those repairs with wire.

@hueyjones70  I too have the same Buddy paint pen. I actually haven't had a great experience with it as also used it to restore my 1200XL's membrane. I found it cracked easily and at times, despite shaklng it sufficiently prior to each use, it would be watery and hard to control the flow rate. Everntually I managed to restore the membrane tracks, etc, but I wished I'd used something else from the outset. I hope it lasts as I really don't want to revisit repainting them again. 

 

Glad it worked for you though. 

[hueyjones70]

If I could get some conductive glue I would do most fixes with fine wire.

[Jeffrey Worley]

On 1/22/2022 at 2:12 PM, gosub_9 said:

Greetings, folks. ??

 

I'm brand new here. At the beginning of this year (2022), I pulled down my ATARI 1200XL off the shelf and made an attempt to bring it back to life. ?

 

After 36+ years in my parent's basement ⌛️ and a few years up in my closet, I finally got off my duff and purchased that 5-pin DIN to AV cable to get 'er hooked up to a monitor.

 

At first power-on? in nearly four decades, she came up like a champ: that beautiful "ATARI" rainbow that had achieved burn-in of heart of this 9 year old so many years ago.

 

Of course, most of you would be shocked if I said everything just worked. Of course not: the keyboard was utterly unresponsive. 

 

(...finally getting to my point...)

 

It was this thread that gave me the gumption ?? to crack that critter up and attempt to bring the keyboard back to life.

It took a couple of weekends, some hand-wringing, some courage (and a touch of stupidity) to get my childhood computer fully functioning.?

 

So, I wanted to say thank you all for having the public conversation/share that helped me envision what success might look like:

• @Dragonstomper — your detailed post at the beginning, here, gave me options. Having a choice helped me ease into the experience. I had hoped that increasing the k-value of all the springs woulda done it... in retrospect, I think I was always destined to life the mylar on this puppy. But I wouldn't have started with that kind of surgery and who knows if I would have abandoned the project.
• @bob1200xl — it was your counter-point post/response that helped built the creative tension in me that ultimate got me to reach for the hair-dryer (and *gasp* razor blade). 

Thank you, gentlemen.

 

I'm keeping a bit of journal as I go: https://sites.google.com/infosysengr.com/gosub9/list/10-help.

 

At first, I was on a mission to hook-up my childhood computer to the Internet  (i.e. build an SIO/Ethernet bridge; I've got some computer engineering and software development chops)... but then, as I started to explore this beautiful sub-culture of retro computing, I bumped into the Fujinet. ZOMG!

 

ANYWAY... thanks again for participating — it made for a welcoming space for me. ?

 

- John (aka GOSUB 9)

 

Folks are going through a lot with these keyboards and it is not necessary.  Take the keyboard apart, peel the part of the membrane that hosts the key targets away from the PCB while leaving the ribbon part that connects the membrane to the PCB.  Clear any bits of loose latex off the pcb and membrane so they don't shift and get under a key, and lay the mylar back down.  Reassemble and test.  You have a wonderful, working keyboard again.

 

The problem is not the membrane or the traces thereon but rather the latex layer.  The latex bonds to the PCB and creates more tension on the mylar than the spring-loaded keys are designed to overcome.

 

If you want to validate this fix before you peel up anything, just take the top of the keyboard off and test the naked PCB and Mylar.  You will find that all keys register when you press on the mylar directly but won't with the keys on top.  This is a matter of tension, not parts.  Unstick the mylar from the PCB and you are golden.

 

Best,

 

Jeff

[hueyjones70]

My efforts have shown that the problem is almost always where the mylar traces connect with the PCB.

[Beeblebrox]

11 minutes ago, hueyjones70 said:

My efforts have shown that the problem is almost always where the mylar traces connect with the PCB.

Mine too. I also found mapping the bad keys and the tracks on the mylar they were on helped me find the bad mylar fingers as it were. I did this by logging the bad keys, then snapping a pic of the mylar and personally I found then drawing on the image in colour the paths really helped.

 

There is a good Flashjazzcat video on the subject which is worth a look at if it hasn't been mentioned in this thread already. 

 

My 1200XL's mylar had a few extra additional probs Inc some damaged tracks. All was fixed by repainting them. Just get a decent conductive track paint, IMHO one that you paint on and is flexible. 

Edited April 29, 2022 by Beeblebrox

[flashjazzcat]

The primary 1200XL keyboard problem has always been where the mylar traces connect to the PCB, owing to the perished adhesive damaging the carbon pads and separating them from the gold plated PCB contacts.

 

Certainly it's possible to encounter individual problematic keys, but I've always found  (having had at least twenty 1200XLs in and out of the workshop over the years) that cleaning the PCB after removing the Mylar to repair the carbon pads, refitting the Mylar and then repeatedly 'working' any keys which still don't work results in a fully working keyboard. Obviously there are also out of the ordinary cases in which the Mylar (or even PCB) themselves has somehow been damaged or there are other peculiar problems, but these are not the norm, and 90 per cent of the time, once the contact point between Mylar and the PCB contacts has been fixed, everything works.

 

There should also be no need to crush the contact point between the Mylar and the PCB with spacers or shims, either, following a proper conductive paint repair, and if you don't get that part right, you'll never have a working keyboard even if you run around trying to address various other secondary issues.

Edited April 29, 2022 by flashjazzcat

[gosub_9]

On 4/29/2022 at 7:00 AM, Jeffrey Worley said:

Folks are going through a lot with these keyboards and it is not necessary.  Take the keyboard apart, peel the part of the membrane that hosts the key targets away from the PCB while leaving the ribbon part that connects the membrane to the PCB.  Clear any bits of loose latex off the pcb and membrane so they don't shift and get under a key, and lay the mylar back down.  Reassemble and test.  You have a wonderful, working keyboard again.

 

The problem is not the membrane or the traces thereon but rather the latex layer.  The latex bonds to the PCB and creates more tension on the mylar than the spring-loaded keys are designed to overcome.

 

If you want to validate this fix before you peel up anything, just take the top of the keyboard off and test the naked PCB and Mylar.  You will find that all keys register when you press on the mylar directly but won't with the keys on top.  This is a matter of tension, not parts.  Unstick the mylar from the PCB and you are golden.

 

Best,

 

Jeff

 

oh wow...

 

So now, I'm totally confused.

 

In the post that started this thread, the first repair mentioned was to rejuvenate each of the springs, one at a time, about 1-2 mm each.

But now, I'm understanding you to say that people are misguided and need only lift and lay back down the mylar to get a working keyboard.

 

Could you clarify what is your advice?

 

...

 

While I'm at it, I'll summarize my own experience:

- OOTB (after 36 years), no keys worked;

- rejuvenating the springs (using the technique you described) brought alive a minor number of keys;

- lifting and replacing the mylar and repeatedly working the keys (pressed each key literally hundreds of times) brought back to life ~80% of the keyboard;

- replacing the mylar entirely and tweaking a few springs led to a fully working keyboard.

[hueyjones70]

I have restored 6 or 8 1200XL keyboards and I have never touched a spring and I have never tapped a key numerous times. I take the screws out of the PCB then with a Q tip I put a little bit of alcohol in each screw hole. That makes it easier to remove the mylar. After removing the mylar, I wipe the dots with alcohol then paint the traces where they connect with the PCB. Then I wipe the PCB with alcohol. I then place the mylar back on the PCB and check the operation by touching each dot to verify that all the keys are connecting. If any dots fail, I paint them with conductive paint. This seldom occurs. Once all the dots are working I place a tiny piece of electrical tape over the section where the mylar and PCB connect, replace all the screws and attach the keyboard.

[Jeffrey Worley]

On 4/30/2022 at 11:03 AM, gosub_9 said:

 

oh wow...

 

So now, I'm totally confused.

 

In the post that started this thread, the first repair mentioned was to rejuvenate each of the springs, one at a time, about 1-2 mm each.

But now, I'm understanding you to say that people are misguided and need only lift and lay back down the mylar to get a working keyboard.

 

Could you clarify what is your advice?

 

...

 

While I'm at it, I'll summarize my own experience:

- OOTB (after 36 years), no keys worked;

- rejuvenating the springs (using the technique you described) brought alive a minor number of keys;

- lifting and replacing the mylar and repeatedly working the keys (pressed each key literally hundreds of times) brought back to life ~80% of the keyboard;

- replacing the mylar entirely and tweaking a few springs led to a fully working keyboard.

I retract the method I started this post with.  It will work, but it isn't necessary.  Rather than increasing the strength of the springs, you can return the keyboard mylar to its proper state by lifting it and laying it back down again according to the method I described this past Saturday.  The mylar has a layer of latex? on the underside.  That isn't supposed to get stuck to the pcb, but with time it does glom on.  That adhesive action prevents the mylar from deforming under the keystrokes.  The mylar when stuck down so is too tight, is out of tolerance.

 

Best,

 

Jeff

[hueyjones70]

Flashjazzcat's video is the standard for KB repair.

[svhovater]

On 5/6/2022 at 10:12 AM, hueyjones70 said:

Flashjazzcat's video is the standard for KB repair.

link please?

[Beeblebrox]

1 hour ago, svhovater said:

link please?

Google is your friend

 

 

[SviRu]

On 2/22/2020 at 4:33 PM, Jeffrey Worley said:

Don't start nothin' won't be nothin'.  ?

 

I've not run into this with this keyboard, but you've handled, like, ALL of them, so I defer to you. ? 

 

For the group, diagnosing this is pretty simple and involves removing the screws from the bottom of the keyboard and separating the halves.  Once done, plug the keyboard (sans keys of course) back into the machine and test the pads on the board using BASIC or the keyboard test in rom to give you some response.  If the keypads produce keystrokes reliably using your fingers to depress them (a lot more powerful stroke than the spring-driven keys themselves), then your Mylar is OK, and you need to follow the instructions in the 1200xl keyboard post a few messages back in this thread.

 

If they DON'T, then you have a mylar problem or, less likely, the IC's mounted to the PCB in the 1200xl, (which are almost universally mounted on the motherboard for other Atari 8-bits).

 

If you have great trouble getting the tested mylar to reliably put down keystrokes when fully assembled, a last resort is to GENTLY and CAREFULLY peel up the mylar from the PCB  WITHOUT TOUCHING the area where the contacts are connected to the PCB.  You want to leave those contacts (lower left-hand side of mylar) well stuck.  Use a flat shim, like a playing card or other stiff, thin item to aid you in this.  The underside of the mylar is coated with a latex barrier which may peel a bit in the difficult spots.  If it starts to peel, stop and work at that spot from the opposite direction.  The places the latex sticks are around the screw holes, and the strakes which press the mylar down on the PCB.  Gentle, careful shimming will peel the mylar away from the top, completely but for the several-contact fingers at bottom.  Once done, examine the mylar for stray bits of latex and remove them gently.  Do the same with the PCB.  Once you are sure the mylar and the PCB are free of debris, lay the mylar back down on the PCB so that it is smooth and even.  It does not stick.  It doesn't have to, really shouldn't.  Now, plug the keyboard in and test the pads again to make sure you have not damaged the mylar and inactivated any keys.  If you have good function, put the keyboard back together and test.  Since the mylar is now free, it will flap on reassembly.  You will of course account for this tendency and, by holding the PCB in its natural, installed orientation, make the keys to it, ensuring a square fit and flat mylar.  Now you can, holding the two halves together tightly, invert the assembly and install a cross of screws.  Install and test the keyboard.  If you have good function, install the rest of the screws without over-torquing any.  You should be done.  It may be gripey for the first few keystrokes.  Operate all keys until you have no gripiness left.

 

If this does not work, you will have to replace the mylar as Bob, the 1200xl god indicates. ?

Spot on. This is my first 1200XL... so it was an enemy territory. First only 3 or 4 keys were working. I though that this must be the connector... But I tried the keyboard without keycaps. Pushing mylar with my finger. All of the keys were working fine. It could not have been the connector. So Jeffrey was absolutely right. The pressure from the sticky mylar was the problem. You have to peel as said the whole mylar from the pcb. I used hairdryer and 0,1mm feeler gauge. That was a blessing. I did not touch the connector. I peeled every key apart from the connector itself. Cleaned PCB with IPA. Now the keyboard works great. 

So my understanding is that if keys do work the solution is to just free the mylar. Do not touch the springs. Photo after peeling. Tried my best to not rip mylar.

 

Edited March 28 by SviRu

[hueyjones70]

On 1/13/2020 at 8:25 AM, flashjazzcat said:

I am no fan of using these things on self-tappers in ancient plastic, especially when tightening (when screw must be carefully backed up to find thread and not over-tightened). Quite happy with manual methods, thank you.

I don't mind using a battery screwdriver to remove the screws but I would never use one to put the screws back in.

[Beeblebrox]

5 hours ago, hueyjones70 said:

I don't mind using a battery screwdriver to remove the screws but I would never use one to put the screws back in.

Me neither. These little screws easily strip out the plastic thread, so it needs to be tightened by hand very gently. I wouldn't go anywhere near any A8 keyboard with these tiny screws with a battery screwdriver. Once stripped it's game over potentially.