walter_J64bit Posted June 13, 2007 Share Posted June 13, 2007 OK my XEGS came in today but the keyboard is partly working Have anyone ran in to this and what the fix for it? Quote Link to comment Share on other sites More sharing options...
Urchlay Posted June 13, 2007 Share Posted June 13, 2007 Not on an XEGS, I haven't... but most likely, the fix is to take the keyboard apart and clean it thoroughly. It's probably a mylar foil (clear plastic) sheet with carbon traces on it, and probably you can open it up and clean it with 90% isopropyl alcohol. Any traces that are missing, you can re-draw if necessary with a solder pen (aka a "circuitwriter"), or a rear-window defroster repair kit from an auto parts store. Another possibility: there are two chips that act as keyboard multiplexers. On the XEGS (IIRC) they're located inside the keyboard, not on the motherboard. They are probably CD4051's. If half the keyboard doesn't work, and the other half does, you could try swapping the two chips. If the working half stops working, and the non-working half starts working, then you need to replace the bad chip. If this is the case, let me know, I have a few extra 4051's thanks to the generosity of several people on here who helped me get my busted 800XL working again. Bad traces or crud between the contacts is a lot more likely than bad chips... though my 800XL suffered from both (somebody spilled orange juice in there years ago, apparently). Quote Link to comment Share on other sites More sharing options...
walter_J64bit Posted June 14, 2007 Author Share Posted June 14, 2007 OK, I'll take the keyboard apart and see what I can do. Thanks! Quote Link to comment Share on other sites More sharing options...
walter_J64bit Posted June 14, 2007 Author Share Posted June 14, 2007 I've opened up the keyboard I've found rust on the metal plate and it looks like some one spilled something and the two chips are solder to that small board. Quote Link to comment Share on other sites More sharing options...
Urchlay Posted June 14, 2007 Share Posted June 14, 2007 I've opened up the keyboard I've found rust on the metal plate and it looks like some one spilled something and the two chips are solder to that small board. Ugh. Soldered, and not socketed, I bet? The rust may or may not mean anything... I'm typing on an IBM keyboard with a rusty metal plate inside, and it doesn't hurt anything... but I don't think I've ever had an XEGS (or any XE) keyboard apart, so I dunno. Did the spill end up directly on the board with the 2 chips on it? Did it go anywhere else? (...and did you clean it all up thoroughly?) Quote Link to comment Share on other sites More sharing options...
walter_J64bit Posted June 14, 2007 Author Share Posted June 14, 2007 I've opened up the keyboard I've found rust on the metal plate and it looks like some one spilled something and the two chips are solder to that small board. Ugh. Soldered, and not socketed, I bet? The rust may or may not mean anything... I'm typing on an IBM keyboard with a rusty metal plate inside, and it doesn't hurt anything... but I don't think I've ever had an XEGS (or any XE) keyboard apart, so I dunno. Did the spill end up directly on the board with the 2 chips on it? Did it go anywhere else? (...and did you clean it all up thoroughly?) I don't have any of the 90% isopropyl alcohol all I have is %70 and it didn't do much for mylar foil. Quote Link to comment Share on other sites More sharing options...
Urchlay Posted June 14, 2007 Share Posted June 14, 2007 I don't have any of the 90% isopropyl alcohol all I have is %70 and it didn't do much for mylar foil. 70% should work fine, it'll just take longer to dry (since it has more water in it). Did even one dead key start working again after cleaning with alcohol? Quote Link to comment Share on other sites More sharing options...
walter_J64bit Posted June 14, 2007 Author Share Posted June 14, 2007 I don't have any of the 90% isopropyl alcohol all I have is %70 and it didn't do much for mylar foil. 70% should work fine, it'll just take longer to dry (since it has more water in it). Did even one dead key start working again after cleaning with alcohol? None of them came back to life, but I'm going try some more. Quote Link to comment Share on other sites More sharing options...
puppetmark Posted June 15, 2007 Share Posted June 15, 2007 I don't have any of the 90% isopropyl alcohol all I have is %70 and it didn't do much for mylar foil. 70% should work fine, it'll just take longer to dry (since it has more water in it). Did even one dead key start working again after cleaning with alcohol? None of them came back to life, but I'm going try some more. At this point I would bet the encoder chips are fried. I would remove them, install sockets and new chips. The chips are cheap and available at most electonic parts suppliers such as jameco.com the chips you need are CD4051. Actually, I might have some. PM me if you would like me to send you two of them with sockets. Quote Link to comment Share on other sites More sharing options...
re-atari Posted June 15, 2007 Share Posted June 15, 2007 At this point I would bet the encoder chips are fried. I would remove them, install sockets and new chips. The chips are cheap and available at most electonic parts suppliers such as jameco.com I think I read the 4051's are situated on a seperate PCB inside the keyboard, and I seem to remember the keyboard housing itself is quite flat. If that's the case, I suggest to check the clearance over these IC's before socketing them. It would be a shame to put in sockets, only to find the combined height of the sockets + IC's in them exceeds the available space, preventing the keyboard to be screwed shut. re-atari Quote Link to comment Share on other sites More sharing options...
walter_J64bit Posted June 15, 2007 Author Share Posted June 15, 2007 (edited) I'll look into getting a new mylar foil before I try to remove any of the IC's. Edited June 15, 2007 by walter_J64bit Quote Link to comment Share on other sites More sharing options...
walter_J64bit Posted June 16, 2007 Author Share Posted June 16, 2007 I'd some more cleaning now can see that pin 8 and pin 9 on the mylar foil are in bad shape. Quote Link to comment Share on other sites More sharing options...
Urchlay Posted June 16, 2007 Share Posted June 16, 2007 Here's something you might try... pick 2 or 3 keys that don't work, and follow their traces back to wherever they go (the pins on the CD4051 chips, probably, or some header or something that connects to the CD4051's). Each key will have two traces, one on the top half of the mylar sheet, and another on bottom. Find both pins for the same key, and short those pins together with a little piece of wire while the XEGS is powered on and sitting at a READY prompt (better yet, use a resistor instead of a piece of wire. 50-100 ohms should be fine. A piece of wire is definitely OK for the 800XL/600XL keyboard connector, but I don't know about connecting it directly to the CD4051's on an XEGS). You should see that letter appear on screen, or not. If you do, it means the chip is working, and the mylar traces are the problem. If you don't, and you're 100% sure you traced everything out correctly, it means the chip is fried. A couple of things I've discovered about the CD4051 keyboard mux chips, while messing with a 600XL and an 800XL: 1. It's possible for a CD4051 to be only partly bad. I have one that doesn't register two columns' worth of keys, but the others all work. 2. Both CD4051's need to be present. If you try to use one by itself, it won't do anything (acts as though both chips were missing). Not sure why this is. 3. The bad CD4051's came out of an 800XL that had something (orange juice maybe) spilled in it a long time ago... so presumably they're easily damaged by spilled drinks. I've also found that discolored traces on the mylar foil aren't necessarily bad, no matter how black they look. Bad traces are caused by missing parts of the trace... get a multimeter if you don't already have one (even a $10 cheapie from Micro Center is better than nothing). The traces read about 60 ohms from end to end on the XL keyboard, and the blackest trace I have reads about the same as the lightest one. A broken trace will of course read infinity (open circuit). Ehhh, and you probably already know this, but make sure you let the alcohol residue dry after cleaning and before hooking up the keyboard... Quote Link to comment Share on other sites More sharing options...
walter_J64bit Posted June 21, 2007 Author Share Posted June 21, 2007 (edited) My new mylar foil came in now I have a fully operational XEGS! Edited June 21, 2007 by walter_J64bit Quote Link to comment Share on other sites More sharing options...
bones Posted June 22, 2007 Share Posted June 22, 2007 Great news! Where did you get one/how much did it cost? Always nice to find sources Quote Link to comment Share on other sites More sharing options...
walter_J64bit Posted June 22, 2007 Author Share Posted June 22, 2007 Great news! Where did you get one/how much did it cost? Always nice to find sources best electronics it ran me $22.00 Quote Link to comment Share on other sites More sharing options...
bones Posted June 22, 2007 Share Posted June 22, 2007 Good to know, will keep that in mind if mine dies. Thanks! Quote Link to comment Share on other sites More sharing options...
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