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Keyboard Problems

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Atari 800XL has been working fine. Suddenly, the keyboard is unresponsive, except that Reset, Option, Select, and Start all still function perfectly. Ideas on what to look for specifically?

 

Thanks,

J.

 

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Those function keys are controlled by the GTIA, the malfunctional ones are controlled by the POKEY.

If your POKEY is socketed, remove, clean and reinsert it. Hopefully its just a grubby contact/debris issue.

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They say the keyboard mux/demux chips (there are two marked '4051') go bad.  Seems unlikely both of yours would suddenly fail, but it's worth pulling, swapping, or replacing those to see if that isn't the issue.

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I had exactly the same problem last week with my 800 XL. Cleaning the keyboard Mylar and connector with isopropyl alcohol solved it (the Mylar looked fine so I suspect that I only needed to reattach the keyboard after cleaning the slot on the PCB).

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Interesting. What keyboard is it? I've never had this problem before. Where did you get your product from? Maybe the one you have is defective and you can return it and get a new one?

 

More information would help

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2 minutes ago, Wrathchild said:

Is this really the level to which AI spam bots are at?! 🤔

 

What are you talking about? Hope that wasn't directed towards me. I just made my account but I'm not a bot.

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Welcome then.

 

As the OP has indicated, they have an 800XL, presumably for some time. There aren't going to be too many variations of keyboard that goes inside there.

 

So for a potential 35+ year old machine, the idea of joining a forum to recommend "Maybe the one you have is defective and you can return it and get a new one?" just seemed a little out of place.

 

So if you have A8 knowledge to share then I wasn't out to offend.

 

From my experience with a 600XL, it was the other way around with the console keys playing up. This was caused by the tracks on the connector from the keyboard to the edge connector on the motherboard breaking. But for that to happen to the main keys and not the console does seem to indicate the issue lies elsewhere.

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19 minutes ago, Wrathchild said:

Welcome then.

 

As the OP has indicated, they have an 800XL, presumably for some time. There aren't going to be too many variations of keyboard that goes inside there.

 

So for a potential 35+ year old machine, the idea of joining a forum to recommend "Maybe the one you have is defective and you can return it and get a new one?" just seemed a little out of place.

 

So if you have A8 knowledge to share then I wasn't out to offend.

 

From my experience with a 600XL, it was the other way around with the console keys playing up. This was caused by the tracks on the connector from the keyboard to the edge connector on the motherboard breaking. But for that to happen to the main keys and not the console does seem to indicate the issue lies elsewhere.

Are you administering the Turing Test?

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1 hour ago, Wrathchild said:

Welcome then.

 

As the OP has indicated, they have an 800XL, presumably for some time. There aren't going to be too many variations of keyboard that goes inside there.

 

So for a potential 35+ year old machine, the idea of joining a forum to recommend "Maybe the one you have is defective and you can return it and get a new one?" just seemed a little out of place.

 

So if you have A8 knowledge to share then I wasn't out to offend.

 

From my experience with a 600XL, it was the other way around with the console keys playing up. This was caused by the tracks on the connector from the keyboard to the edge connector on the motherboard breaking. But for that to happen to the main keys and not the console does seem to indicate the issue lies elsewhere.

 

Yeah sorry, I got an email from this forum to finish creating my account, I stumbled upon this site a few days ago (I have a blog on keyboards so that might be how I found it, some long tail keyword I guess), I had a few drinks tonght to be honest and that was the first thing I thought to say lol. I'd have to do some research to find more answers on this topic, sounds interesting. 

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Replaced POKEY. No effect. So, I replaced the entire keyboard with a spare I had on hand, which solved the problem. Looks like the faulty keyboard has a replacement mylar. No obvious defects or signs of unusual wear and tear, so I have no clue what would have led to an immediate failure like that.

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I just learned my 600XL has keyboard problems as well. The fun never ends with a $30 machine but I'll get it. I

 

Backspace, <, >, 9,8,7 suffers from severe intermittency. Shift and control keys appear to be down for the count. 

 

Going to take it apart and clean Mylar and slot connections. Wish me luck.

 

 

 

 

Edited by JagChris

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21 minutes ago, JagChris said:

I just learned my 600XL has keyboard problems as well. The fun never ends with a $30 machine but I'll get it. I

 

Backspace, <, >, 9,8,7 suffers from severe intermittency. Shift and control keys appear to be down for the count. 

 

Going to take it apart and clean Mylar and slot connections. Wish me luck.

 

 

 

 

It's likely a Mylar issue but an easy thing to check is to swap the 4052 mux chips inside the machine and see if the problem keys remain the same or not. If they change, one of the chips is bad, which is a cheap fix although inconvenient to have to order parts and there's likely going to a minimum-quantity issue with most electronics parts retailers. 

 

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Mux chips huh? That's probably above my pay grade. I'll have to hope it's a Mylar problem.

 

I took apart shift keys and they showed a brief moment of life when I reassembled them. Hoping this is something a good cleaning will fix.

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since you have other issues mentioned in other threads... I'd focus on Pokey and the 4051's, can't hurt to do a cleaning at the time, just be gently and don't use any strong solvents on the mylar...

since the lids and shields will be off, look everything over, clean and reseat, no leaking or bulging caps, or burnt components, no dead bugs or spiders... or rust for that matter... we've seen it all...

Edited by _The Doctor__
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I'm going to try this guys deep dive Mylar clean since I've never done it before.

 

Which one of you is this?

 

In the comments for the keyboard video someone says the chips that go bad are a dollar apiece. I'll have to grab a few and squirrel them away. 

 

About the power. Yes I'm using the usb A-B connector power cord that came with the SD max. But the outlet end is what I was referring to. is it ok for it to be hooked to low voltage power sources 1.0a or some such or into laptop/pc usb. Anyways it seems fine so far.

 

I wonder how the OPs situation turned out.

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I'm confused, as I hear you this or that works fine, with a caveat 'it has to warm up' or it doesn't do this, or the keyboard doesn't etc...

it's not fine... You shouldn't have to wait for things to warm up, the keyboard should work etc...

 

In any event, the outline of cleaning and re-seating, small mods to check or do, and powering the devices as described are quite accurate and leads to a reliable long lived experience. Grabbing the chips is good as well. After doing those things, if problems persist, replacing with those chips, and or the Pokey are also the proper course of action.

 

Hopefully it's understood that we are all pulling for you and wish the best possible outcome, and in fact some here are looking out for the long life of your equipment even more so. Best of luck.

 

_T D__

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Fine was just a reference to the sdmax firing up by itself. It's communication with the Atari is another thing...

 

Yeah it was recommended strongly by a couple people no alcohol on the Mylar. Only window cleaner on an appropriate clothe for wipe down. I appreciate all the help. I'm very excited as I haven't messed with the 8bit in 20 years. I feel giddy

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As you have a 600xl everything is socketed so swapping the 4051's and re-seating pokey before you knacker the mylar would be a good first step imo

And as window cleaner contains alcohol tread very carefully

Edited by mimo

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41 minutes ago, mimo said:

As you have a 600xl everything is socketed so swapping the 4051's and re-seating pokey before you knacker the mylar would be a good first step imo

And as window cleaner contains alcohol tread very carefully

Note to the OP: those are the keyboard mux chips I referenced earlier. They translate the matrix signals from the keyboard Mylar to the KB data lines to the POKEY chip.

 

Also to @mimo - most window cleaner contains ammonia, not alcohol. Both isopropyl alcohol and ammonia are solvents - rather strong ones, at that. Personally, I’ve cleaned Mylars with iso alcohol with no issues in the past. The key is to not use a lot of force no matter what you’re using, especially around the carbon contacts. A quick wipe with a cotton swap or pad to get rid of any surface oxidation and that’s all you need. 

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18 hours ago, JagChris said:

Backspace, <, >, 9,8,7 suffers from severe intermittency

these keys all share pin 1 - see image

600xl_7.thumb.png.7f4f35f349b740e08b672449f7f0ad6b.png

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On the above I'm assuming that diagram refers to the ribbon cable? What's good protocol for cleaning the ribbon cable slot? Usually something like this is a credit card and clean t shirt scrap dipped in alcohol.  I am not sure that applies here. Just blow it out?

 

How about the copper contacts on the ribbon cable end? 

 

As for knackering the Mylar I'll try to be gentle as possible but it probably needs to be done one way or the other. Is there replacement Mylar for these? If not thats a reproduction to look into. The man in the video referred to reflective paint as a possible fix for cracks.

 

I'm assuming there are chip pullers to use for these ICs or will they pop in and out by hand?

 

You guys are great.

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12 minutes ago, JagChris said:

On the above I'm assuming that diagram refers to the ribbon cable? What's good protocol for cleaning the ribbon cable slot? Usually something like this is a credit card and clean t shirt scrap dipped in alcohol.  I am not sure that applies here. Just blow it out?

 

How about the copper contacts on the ribbon cable end? 

 

As for knackering the Mylar I'll try to be gentle as possible but it probably needs to be done one way or the other. Is there replacement Mylar for these? If not thats a reproduction to look into. The man in the video referred to reflective paint as a possible fix for cracks.

 

I'm assuming there are chip pullers to use for these ICs or will they pop in and out by hand?

 

You guys are great.

Replacement mylars are available from a few sources, I bought one from @Duddie and it is of excellent quality 

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sometimes the connector pins are folded too far back to make contact.

a bit of bending with a screwdriver or craft knife can move them back into place

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