My Atari 800 Keyboard Repair

[Arcanis-Will]

Here is a summary of what I found when fixing the 10 or 11 "broken" (non-working) keys on my Atari 800. Not in any particular order. Hopefully this will help others.

 

• The root cause for all broken keys was that the solder pad(s) for those keys had been lifted off the underlying PCB. Appears some kind of force was applied to the key and/or they were mounted in a way that allowed pressure on the keys to push the solder pads away from the PCB. This popped the pads free which in turn broke continuity at just about every pad. Some pads made intermittent contact. The effect was that every pad made a break in the circuit which prevents the key and all others after it from working.
• The keys themselves were fine. The mechanical mechanisms worked. This was verified by using a multimeter to test each key directly. Probe right at the contact points for that key where it is soldered to the PCB.
• You may not be able to see the breaks. You will need to use a pencil or test probe to push on each key's solder points. There are 2 leads from each key that will stuck up slightly at the PCB and you can push on the sharp end of the lead to see if it moves. If the key's lead wiggles at all, then your solder pad is loose / broken and you need to jumper it with wire for best fix.
• The fix was to solder wire from the nearby working neighbor keys (as per the circuit diagram) which thus restored continuity.
• You will need to carefully remove as much of the foam mess as you can without further damaging the traces. You cannot test continuity across the PCB without removing the foam at least off each solder joint.
• Check continuity from the connector at the end of the ribbon cable down onto the PCB connection. This rules out the ribbon cable.
• Use the Atari key scan matrix diagram to figure out which pins on the ribbon cable connect to which keys.
• The diagram tells you which ribbon cable pin goes to which key, so visually follow the trace from the incoming PCB pad of the ribbon cable up across the board to the first key. Check that path with a meter. Then check from that key to the next (as per diagram and / or the circuit traces themselves).
• Simply touching up / resoldering each pad will not repair a problem where the pad is actually lifted and disconnected from the traces. You need to add your own wiring to make contact to - and across - the lifted pad so that what was once an isolated key is now part of the chain again.
• I jumpered across the non-functional pads and soldered at each point, effectively making my own traces to replace the many damaged ones on the board.
• It is not high-current - I used some spare wire-wrap wire that I had from some long time ago project.
• After resoldering everything, I used a printout of the scan matrix and checkmarked each and every connection as I retested them with a meter. You want to verify that the incoming ribbon cable pad at the PCB has continuity up through each key that it is supposed to interact with.
• Reading glasses helped a lot.

 

 

 

 

 

 

 

 

Edited March 5, 2014 by Arcanis-Will

[john-m]

I have an Atari 800 with a partially working keyboard. When I say partially, very few of the keys work at all

But there is one big difference from yours!

Instead of a ribbon cable connecting the keyboard, it is all hard wired.

I read somewhere that a person that had my style keyboard connector sent it to Atari for repair and that both the keyboard and motherboard were replaced.

On my keyboard, there is green corrosion at the points where the wires connect to the keyboard and the header at the other end fails to unplug from the right angle curved wire risers coming from the motherboard.

Any suggestions in what steps I should take to try to rectify this situation?

Also, with the wired keyboard connector vs a ribbon cable connector, about what vintage would you think the 800 was?

 

[Arcanis-Will]

I'm not completely sure I understand what you are describing by hard wired. To me, hard wired means no connector - both ends soldered - but you mention that the other end does have a header. Do you mean that it's not a ribbon cable and is instead a set of separate wires going to the header? The female header at the end of my ribbon cable was very well stuck onto the pin header and it took a lot of careful prying. Plus you have to be sure that the end of the header is raised enough to clear the edge of the shield or PCB - there was something that otherwise interfered with the header coming straight off.

 

If you had a picture it would be easier to visualize. Are you referring to something like this? I can't find any other references online at the moment. If that is what yours is like, the header (at top of pic) will indeed come off the pins but you have to ease it off carefully.

 

http://1.bp.blogspot.com/-pw80_H6Aw1E/Tzf19oQ9ZCI/AAAAAAAAABU/ts9La9FwPgk/s1600/2012-01-29_15-51-48.jpg

 

To your other question, I don't know how to judge the vintage but maybe someone else will.

[ACML]

Arcanis-Will,

 

Nice work! I have fixed several Mitsumi, Stackpole and a Hi Tek 800 keyboard, but my Hi Tek only had a bad space bar (pad 57 popped off). Makes you wonder how so many of the traces lost continuity. Must have been abused???? The Hi Tek is probably the finest quality keyboard Atari ever used. The mechanical switches with gold plated contact fingers should last a long time. The Stackpole is nice, but those darn yellow plungers all crack in the corners over time, even if not used. The cracks allow the key to press too far and the key can bind in the closed position, but more often has too much free play on the way up resulting in the key popping off. I will definitely save this post if my Hi Tek ever has this issue. Thanks!

[john-m]

The link you supplied looks just like my keyboard and the way it is connected with wires instead of a ribbon cable.

The part of the picture that shows the wires going into the keyboard are corroded on mine. I tried my best to get the keyboard

header to disconnect from the motherboard riser. But quit before the force involved damaged the header. I have not tried to disassemble the keyboard taking out all the small screws and separating the sections of it as to the PCB, keyboard membrane, and the keys.

I am concerned about possible damage to the membrane such as tearing. Also, I will have to ohm out the wires to it after cleaning up the corrosion to check for continuity.

I have checked on replacement keyboards; but the only ones I can find in very limited supply are the ribbon cable type and am unsure of what would be required as to connector modification.

For now, this project is on the back burner.

 

[unixdude]

I'm having exactly this issue today with my 800's Hi-Tek keyboard, and I'm wondering how you got the double-sided sticky-tape-foam off without damaging the board.  I'd love some suggestions on doing that.

[Arcanis-Will]

1 hour ago, unixdude said:

I'm having exactly this issue today with my 800's Hi-Tek keyboard, and I'm wondering how you got the double-sided sticky-tape-foam off without damaging the board.  I'd love some suggestions on doing that.

I think that I used a cleaner called Goo-Gone to help soften and dissolve the foam. Use it somewhat sparingly. You can then use alcohol to wipe off the goo-gone and residue.

[flashjazzcat]

Here's a radical repair job I just completed on a Hi-Tek keyboard:

 

 

The spring contacts under the spacebar were broken off at the bottom of the frame (where they would normally be soldered to the PCB) in such a manner that they couldn't even be 'dug out' after drilling a hole in the PCB, so I initially gave up and pronounced the keyboard dead. But today I had the idea of actually cutting a chunk of the frame - switch and all - off a donor (another, even more badly damaged and irreparable Hi-Tek) and grafting it onto this one. So that's what I did. Took about three hours' work and a couple of attempts to get the alignment and tension right but it works. Unfortunately when I thought it was all done I noticed the contacts under the 'X' key were badly twisted and preventing the key from rebounding properly (you can see it's sitting low in one of the photos), but I managed to fix that in an hour and a half with a pair of needle-nose pliers and an enormous amount of patience.

 

Anyway: the reason these keyboards are a pain in the arse to fix is that the spring contacts are moulded into the plastic frame with the legs sticking out the underside. The legs are then soldered to the PCB, but even if you desolder every single switch to get the whole frame off the PCB, if the broken switch legs cannot be soldered to or if the spring contacts are destroyed on the top side such that they cannot be bent back into shape, repairs are next to impossible.

Edited November 6, 2019 by flashjazzcat

[CZroe]

Mine was just a bad shift register/encoder chip. Switching the two chips around swapped the keys which were affected. Replacing it restored them all... except for the Star key. That one needed yo be flooded with isopropyl and worked a bunch of times. Kinda needs it again too.

[Sugarland]

2 hours ago, flashjazzcat said:

Here's a radical repair job I just completed on a Hi-Tek keyboard:

 

 

Great!! That's a beautiful 800, too.  Making a mental note you repair 800 keyboards. ?   I had no idea the contact wings were molded into the plastic. I'm afraid to take one apart in fear of ruining it.

[flashjazzcat]

15 hours ago, Sugarland said:

Making a mental note you repair 800 keyboards.

There isn't much I won't repair (in the way of Ataris, at least). And even if it looks hopeless, I'll usually have a go anyway.

15 hours ago, Sugarland said:

I had no idea the contact wings were molded into the plastic.

Nor did I until I studied the Hi-Tek's assembly really closely. I was quite horrified when I realised the truth. All it takes is for someone to put one of the plungers back with the crossbar running left-right instead of on the vertical axis, and the contacts are destroyed when the key is pushed home, and this in turn may mean the entire keyboard is effectively done for. Even if the plunger is reinserted properly, if the crossbar doesn't part the two contacts when pushed home, it can crush and distort them such that the key no longer works properly.

 

Another issue is corrosion on the contacts, but thankfully this can usually be overcome with a little switch cleaner. This was the case with the keyboard pictured. Even with the space bar and 'X' key working and the machine fully reassembled, I spent a further half an hour or so testing every key in turn and popping the caps off where necessary in order to clean the contacts. I think it took some six hours in total to transform the keyboard from wrecked to fully functional.

 

Edited November 7, 2019 by flashjazzcat

[adam1977]

On 11/7/2019 at 4:37 PM, flashjazzcat said:

There isn't much I won't repair (in the way of Ataris, at least). And even if it looks hopeless, I'll usually have a go anyway.

Nor did I until I studied the Hi-Tek's assembly really closely. I was quite horrified when I realised the truth. All it takes is for someone to put one of the plungers back with the crossbar running left-right instead of on the vertical axis, and the contacts are destroyed when the key is pushed home, and this in turn may mean the entire keyboard is effectively done for. Even if the plunger is reinserted properly, if the crossbar doesn't part the two contacts when pushed home, it can crush and distort them such that the key no longer works properly.

 

Another issue is corrosion on the contacts, but thankfully this can usually be overcome with a little switch cleaner. This was the case with the keyboard pictured. Even with the space bar and 'X' key working and the machine fully reassembled, I spent a further half an hour or so testing every key in turn and popping the caps off where necessary in order to clean the contacts. I think it took some six hours in total to transform the keyboard from wrecked to fully functional.

 

Do you know if 800 keyboards are interchangeable at all? Would a Hi-Tek keyboard fit an 800 that originally had a Mitsumi? ?

[flashjazzcat]

1 hour ago, adam1977 said:

Do you know if 800 keyboards are interchangeable at all? Would a Hi-Tek keyboard fit an 800 that originally had a Mitsumi?

Yes: they should be interchangeable without issue.

[adam1977]

Many thanks ?

[Getafix]

I just got my first Atari 800, a gift.  The top row of keys work, but the second row down has dead keys.  In the top row, the "1" key didn't work till I pressed it a bunch of times and then it started working.  This didn't fix other keys, for example, the F key and most keys around and below.  Space bar is also dead. 

 

I have taken it apart.  It says Mitsumi.  To me, the keyboard seems clean and in excellent condition.  In a video I found the white film was separated from the PCB.  The guy in the video says "this has helpfully been removed by the owner, saves me warming it up".  I am at a loss for what to do now.  Should I steam it off or something?  Is that advised, getting the film off of the PCB, as the next step in cleaning?  Any suggestions welcomed (perhaps I need to check something else before I dismantle this piece any further?).  Thank you.

[Sugarland]

On 6/8/2020 at 3:32 AM, Getafix said:

I just got my first Atari 800, a gift.  The top row of keys work, but the second row down has dead keys.  In the top row, the "1" key didn't work till I pressed it a bunch of times and then it started working.  This didn't fix other keys, for example, the F key and most keys around and below.  Space bar is also dead. 

 

I have taken it apart.  It says Mitsumi.  To me, the keyboard seems clean and in excellent condition.  In a video I found the white film was separated from the PCB.  The guy in the video says "this has helpfully been removed by the owner, saves me warming it up".  I am at a loss for what to do now.  Should I steam it off or something?  Is that advised, getting the film off of the PCB, as the next step in cleaning?  Any suggestions welcomed (perhaps I need to check something else before I dismantle this piece any further?).  Thank you.

A hair dryer will warm it up but don't use high heat.   I think the issue is broken traces on the mylar or more likely the contact pads have been worn off. I'm not sure but I think conductive paint will fix it. A window defog repair kit from an auto store might work too.  I also just got an 800 with a Mitsumi keyboard and many keys did not work. Pressing the keys many times has improved function but it's still not very usable.

[StickJock]

One of my 800s had a completely dead Mitsumi keyboard.  None of the keys worked.  I fixed it by carefully peeling the membrane away from the PCB (heated it up to soften it a bit) but not where it was connected to the PCB.  Clean the PCB and let the membrane lay back down.  Put it all back together again and all of my keys worked.  Well, one of them was a bit flaky, but some banging on it brought it back to the same sensitivity as the others.  

 

Give this a try.  It took me a while to get around to this because I was *sure* that I had a bad IC, so I waited weeks for new chips to get here from AliExpress.  After I finally ruled everything out (swapped KBs, bad KB followed the actual KB, good Stackpole KB worked on both machines), I did the above and now everything is good.

 

 

[Sugarland]

34 minutes ago, StickJock said:

One of my 800s had a completely dead Mitsumi keyboard.  None of the keys worked.  I fixed it by carefully peeling the membrane away from the PCB (heated it up to soften it a bit) but not where it was connected to the PCB.  Clean the PCB and let the membrane lay back down.  Put it all back together again and all of my keys worked.  Well, one of them was a bit flaky, but some banging on it brought it back to the same sensitivity as the others.  

 

Give this a try.  It took me a while to get around to this because I was *sure* that I had a bad IC, so I waited weeks for new chips to get here from AliExpress.  After I finally ruled everything out (swapped KBs, bad KB followed the actual KB, good Stackpole KB worked on both machines), I did the above and now everything is good.

 

 

Awesome thank you I'll give that a try!

[mimo]

My memory is a bit hazy, but is the 800 mylar similar to the 1200xl? in as much as it has the contact "fingers"?
I fixed my 1200 by just cleaning the adhesive from this area.

 

 

Images stolen from @flashjazzcat 's brilliant video 

 

[mimo]

lol, John had actually done this repair on his channel ?

 

 

[Sugarland]

On 7/6/2020 at 7:41 PM, StickJock said:

One of my 800s had a completely dead Mitsumi keyboard.  None of the keys worked.  I fixed it by carefully peeling the membrane away from the PCB (heated it up to soften it a bit) but not where it was connected to the PCB.  Clean the PCB and let the membrane lay back down.  Put it all back together again and all of my keys worked.  Well, one of them was a bit flaky, but some banging on it brought it back to the same sensitivity as the others.  

 

Give this a try.  It took me a while to get around to this because I was *sure* that I had a bad IC, so I waited weeks for new chips to get here from AliExpress.  After I finally ruled everything out (swapped KBs, bad KB followed the actual KB, good Stackpole KB worked on both machines), I did the above and now everything is good.

 

 

This worked!! Didn't even clean the PCB afterwards.

 

I left the gold fingers area (yellow area photographed by @mimo above) alone but very carefully and slowly peeled away the rest of the mylar, especially around all key contact pads. Used a gift card since it is thin, has rigidity and is big (lol). The rubber wants to stay stuck to the PCB (bad!) especially around where the screws go through. The trick is to heat the mylar with a hair dryer. If the rubber sticks to the PCB, just peel from the other side while being patient and careful to the details. A little bit of the rubber will stick around some screw holes but that doesn't affect the keyboard function. Seems to me the important part is to get the rubber+mylar separated around each key pad area. Then let it rest place again and put it all back together again. One small piece of the rubber tore around one key pad and I just placed it back there as best as possible. So far so good! No idea how long this fix will last.  Maybe it's even possible to re-paint a new rubber layer onto the mylar, if necessary...?    So don't throw out the Mitsumi variant mylar guys. Someone could restore the rubber layer.

 

Edited July 8, 2020 by Sugarland

[StickJock]

Glad to help.  I wish I had done this sooner, but the laziness is strong in me and that was a lot of screws.

[Gunstar]

On 3/5/2014 at 1:58 PM, Arcanis-Will said:

Here is a summary of what I found when fixing the 10 or 11 "broken" (non-working) keys on my Atari 800. Not in any particular order. Hopefully this will help others.

 

• The root cause for all broken keys was that the solder pad(s) for those keys had been lifted off the underlying PCB. Appears some kind of force was applied to the key and/or they were mounted in a way that allowed pressure on the keys to push the solder pads away from the PCB. This popped the pads free which in turn broke continuity at just about every pad. Some pads made intermittent contact. The effect was that every pad made a break in the circuit which prevents the key and all others after it from working.
• The keys themselves were fine. The mechanical mechanisms worked. This was verified by using a multimeter to test each key directly. Probe right at the contact points for that key where it is soldered to the PCB.
• You may not be able to see the breaks. You will need to use a pencil or test probe to push on each key's solder points. There are 2 leads from each key that will stuck up slightly at the PCB and you can push on the sharp end of the lead to see if it moves. If the key's lead wiggles at all, then your solder pad is loose / broken and you need to jumper it with wire for best fix.
• The fix was to solder wire from the nearby working neighbor keys (as per the circuit diagram) which thus restored continuity.
• You will need to carefully remove as much of the foam mess as you can without further damaging the traces. You cannot test continuity across the PCB without removing the foam at least off each solder joint.
• Check continuity from the connector at the end of the ribbon cable down onto the PCB connection. This rules out the ribbon cable.
• Use the Atari key scan matrix diagram to figure out which pins on the ribbon cable connect to which keys.
• The diagram tells you which ribbon cable pin goes to which key, so visually follow the trace from the incoming PCB pad of the ribbon cable up across the board to the first key. Check that path with a meter. Then check from that key to the next (as per diagram and / or the circuit traces themselves).
• Simply touching up / resoldering each pad will not repair a problem where the pad is actually lifted and disconnected from the traces. You need to add your own wiring to make contact to - and across - the lifted pad so that what was once an isolated key is now part of the chain again.
• I jumpered across the non-functional pads and soldered at each point, effectively making my own traces to replace the many damaged ones on the board.
• It is not high-current - I used some spare wire-wrap wire that I had from some long time ago project.
• After resoldering everything, I used a printout of the scan matrix and checkmarked each and every connection as I retested them with a meter. You want to verify that the incoming ribbon cable pad at the PCB has continuity up through each key that it is supposed to interact with.
• Reading glasses helped a lot.

 

 

 

 

 

 

 

 

Thanks for this guide to your repairs! I've never worked on a Hi-Tec keyboard before, and realized there was no way to take it fully apart (mine at least; it doesn't even have screws in the bottom like yours). My keyboard was in full working order, but had cracked plungers I was replacing while doing and Incognito install at the same time, and even though it was working, I noticed about a half dozen cold or cracked solder points on the keyboard so I resoldered those points. But afterward NONE of the keys worked except for the BREAK key, which is at the beginning of the circuit on it's line/trace (15 IIRC). So I have to attempt a repair very much like you did here myself now, and I'll follow your lead here.

[Gunstar]

On 4/13/2020 at 3:16 AM, adam1977 said:

Do you know if 800 keyboards are interchangeable at all? Would a Hi-Tek keyboard fit an 800 that originally had a Mitsumi? ?

Yes, you can interchange the kevboards, but you will most likely have to install a new keyboard ribbon connector on your 800's motherboard since there were different connectors there for different brand keyboards and even some with the same brand keyboard had different ribbon cables and connectors.

Edited July 18, 2020 by Gunstar

[unixdude]

Anybody got any tips on safely removing the foam?