Atari 800 (not XL) Mylar keyboard repair help

[EpikalPuppy]

Today, I got my first ever Atari 8-bit computer, and Atari 800. This one is a pretty late production run (late '83) and has a Mitsumi mylar keyboard. About 80% of the keys on the keyboard work, and I really like the feel of it, I just wish it worked better. I have heard of silver paint being used to repair the traces on the mylar, but I'm unsure of how safe it would be for me to do this, as I have just started messing around with these things. Another problem is that I can't seem to find the correct silver paint. When I look on ebay, there are either large vials of silver paint for a very high price, or syringes from China with tiny amounts that I don't exactly trust. If somebody has a really good guide on how to do this repair, knows somebody who could do this repair for me, or knows where I can find an appropriate amount of good silver paint that doesn't cost too much, I would really appreciate it. Thank you.

[Paul Westphal]

Best Electronics in San Jose CA sells brand new keyboard myylars.

[TGB1718]

Might be an idea to note which keys work and which don't, then check against the keyboard matrix,

It may be a connection to a common set of keys, before you start using the paint remedy

 

Part way down the page on the link below is the matrix layout

 

https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwiDzsjlo_LmAhUQyYUKHa2ZCaoQjRx6BAgBEAQ&url=http%3A%2F%2Fblog.pixelpracht.net%2F%3Fp%3D710&psig=AOvVaw30pn0QnszXhTycCiT0E4_C&ust=1578513668645662

[EpikalPuppy]

6 minutes ago, TGB1718 said:

Might be an idea to note which keys work and which don't, then check against the keyboard matrix,

It may be a connection to a common set of keys, before you start using the paint remedy

 

Part way down the page on the link below is the matrix layout

 

https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwiDzsjlo_LmAhUQyYUKHa2ZCaoQjRx6BAgBEAQ&url=http%3A%2F%2Fblog.pixelpracht.net%2F%3Fp%3D710&psig=AOvVaw30pn0QnszXhTycCiT0E4_C&ust=1578513668645662

Thanks a lot! I’ll try this when I get home.

[EpikalPuppy]

12 minutes ago, Paul Westphal said:

Best Electronics in San Jose CA sells brand new keyboard myylars.

As far as I can tell, all keyboard mylars that are currently being sold are for XL computers, I’ve never seen on for the 800.

[Paul Westphal]

Oops my bad . I thought he said xl. Correct.

[TGB1718]

41 minutes ago, EpikalPuppy said:

As far as I can tell, all keyboard mylars that are currently being sold are for XL computers, I’ve never seen on for the 800.

Your right, I wasn't thinking, it's switches on the 800, but the matrix is still the same

[erichenneke]

You really don't have anything to lose to try the conductive paint trick.  It has worked for me well every time, and it really isn't very useful to you the way it is now I assume. 

 

You just have to be patient and a continuity tester or multimeter helps so you can test each trace as you fix them.  

 

I just use the stuff that comes in auto rear window defrost repair kits, which you can get from Amazon. And just use a tooth pick or a very very fine brush. 

 

I've done this to about 5 systems as "temporary fixes" over the years,  and every one of them not only worked but have held up fine that way.  In fact I have some new XL mylars I bought just in case,  and haven't had to use them yet! 

 

One clarification though,  I've never done this to a 800. Only for XL and  XE.

[adam1977]

Rich (RWAP) started an interest thread a few months ago about replacement mylars 

[EpikalPuppy]

I must be lucky or something, but when I disassembled the keyboard, I couldn’t find any broken traces. I don’t have the paint yet, so I was just doing this out of curiosity. I decided to wipe everything down with alcohol and put it back together. Lo and behold, this was enough to get it working! The keyboard works absolutely perfectly now. I guess now I should retrobright it, too bad it’s January...

Edited January 8, 2020 by EpikalPuppy

[EpikalPuppy]

6 hours ago, TGB1718 said:

Your right, I wasn't thinking, it's switches on the 800, but the matrix is still the same

As for this, I was under this impression too, however, when I took it apart, it was a Mitsumi mylar keyboard, the same one used on the XL. This one has a date code of 093, which I believe is the ninth week of 1983, which would be pretty late in the production run. I believe at that time, they were probably mixing and matching parts and some 800’s ended up with XL mylars.

Edited January 8, 2020 by EpikalPuppy

[ACML]

The repair procedure is on Retrobits.net

http://retrobits.net/atari/keyboard.shtml

It's for the 1200XL, but the repair is the same.

 

The conductive paint you want is BARE.

https://www.amazon.com/Bare-Conductive-Electric-Paint-10ml/dp/B00KBXT6JW

It's a bit thick, but I'd use a toothpick to apply it on the traces on the mylar.

 

also see:

 

 

 

[+slx]

I got one of RWAPs replacement mylar and installed it. When I got that 800 a couple of years ago and found out about the dead keyboard, I left it unconnected and now can't remember which way the connector should go on. One way I get constant keypresses, the other way a dead keyboard.

 

Any idea/hint which way the connector should point or how I could find that out using a continuity tester?

 

Is there a chance I killed something by attaching it wrong way round?

 

Thanks!

[Sugarland]

On 1/17/2021 at 12:59 PM, slx said:

I got one of RWAPs replacement mylar and installed it. When I got that 800 a couple of years ago and found out about the dead keyboard, I left it unconnected and now can't remember which way the connector should go on. One way I get constant keypresses, the other way a dead keyboard.

 

Any idea/hint which way the connector should point or how I could find that out using a continuity tester?

 

Is there a chance I killed something by attaching it wrong way round?

 

Thanks!

 

The cable stays straight. The connection is easy to get the pins wrong but take it slow and you'll see there's only one way it will connect. Look at the female side and you'll see that some of the holes are missing (slotted?). So the connection stays more to one side (left I think) of the female plug. There is one extra hole on the right edge (as seen from front of computer) of female connector that is unused iirc.

 

 

Edited January 21, 2021 by Sugarland

[+slx]

3 hours ago, Sugarland said:

The cable stays straight. The connection is easy to get the pins wrong but take it slow and you'll see there's only one way it will connect. Look at the female side and you'll see that some of the holes are missing (slotted?). So the connection stays more to one side (left I think) of the female plug. There is one extra hole on the right edge (as seen from front of computer) of female connector that is unused iirc.

Interesting, I'll have another look although I'd swear the connector is symmetrical and has as many holes as there are pins on the motherboard and fits either way. It's a bit fickle to fit as the holes are quite tight on the female side and the pins are angled, thus easy to bend. I'll make some photos the next time round.