holly@osu-eddie.UUCP (Joe Hollingsworth) (05/05/87)
A week or so ago I sent the following to comp.sys.ibm.pc: >I have a PC XT, with a 5150 type keyboard. The keyboard is malfunctioning. >The <esc> key works maybe once every 10th strike and other keys such as >the <o> key double strike (produce two o's for one strike of the key). >Has netland had experience in getting keyboards repaired? The questions >that come to mind are: Can this type of malfunction be repaired? If >I knew which chip(s) were malfunctioning, could I fix it myself? Is >it cheaper to buy a new keyboard? I received a number of responses most of them were along the following line: Your problem may be dirty switches in the keyboard mechanism (I don't guarantee that, but you should check it out). By removing the keycaps by careful prying, you should be able to get to the mechanism and clean them with appropriate solvents (available at Radio Shack). or, The esc key is very easy to repair. Just unsolder the connections on the back of the pc board and remove the switch. The switch should just unsnap. Use some head cleaner and spray on the contacts, make sure the depression points on the switch are sound and use some wd40 type lubricant on the shaft and reinstall the switch. 99% of the keyboards I fix are this problem. For the other problem look and see if there are any socketed TI chips. If there are pull the chip and scrape the corrosion off of the pins. TI does not use a alloy for their pins so they get corroded if they are socketed. The other possibility is to look at the character generator chip. Well I followed the above advice and this is what I found. Each key has its own switch. Each switch has two electrical leads that are soldered to the keyboard pwb board. I could not take the switch apart without unsoldering the switch and removing it from the rest of the assembly because the latches that hold the top part of the switch to the bottom part were below a metal frame that gave the whole assembly support. Once that the switch was out (I used a soldering gun), I could easily take it apart. Alas cleaning didn't seem to help my esc key switch. So I robbed the + key switch from the number pad area at the right end of the keyboard. I don't use that key anyway and I have the other + key on the top row of the keyboard. I just switched the + key and esc key switches. The esc key works now, the + key doesn't. Thanks for your help. Joe -- : Joe Hollingsworth : Department of Computer and Information Science : USMail:The Ohio State University : 2036 Neil Avenue Columbus, OH USA 43210-1277 : ARPA:holly@ohio-state.{arpa,csnet} : UUCP:...!cb{osgd,att}!osu-eddie!holly