EEVblog #1245 – A Most Excellent REPAIR: IBM PCjr Keyboard

laatste update: 05-2022


Can you find the fault in the IBM PCjr wireless keyboard before Dave does?
A most excellent adventure in troubleshooting.

Forum:

#Repair #IBM #Vintage

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30 gedachten over “EEVblog #1245 – A Most Excellent REPAIR: IBM PCjr Keyboard”

  1. The main issue with that keyboard was the bad stabilizators. My BTC also works on a similar conductive rubber dome over PCB design (but with Cherry MX compatible sliders), but at least the wire stabilized keys worked very well after a good clean – which meant complete disassembly, and a bath in a warm, soapy water. The pin stabilizers needed some lubricant in the form of some universal grease (which I also applied to the wire stabilizers), the result was the best feeling keyboard I've ever owned. Probably some better Alps switch would outdo it in almost every way, but I couldn't try any of those.

  2. The ~400 kHz sounds like the carrier signal for the infrared, which is then modulated by the bit pattern of whatever key is pressed (turning on/off the carrier signal to the IR LED's as needed). Maybe you could do an episode about how IR remotes actually work (gated carrier on the TX, narrow bandpass on the RX), and why some early systems were prone to random receptions by just having sunlight shining on the receiver.

  3. I think Dave should make a video on how to interpret Australian sayings… I mean I sort of get them, but more explanation would be great. Dave would probably just insert more sayings into his explanations… Fun times to be had…

  4. Gotta admit, when I first saw this guy I was put off by his voice. Now though, I not only have a great respect, but actually find him refreshing and entertaining!! Obviously knowledgeable and passionate. It great you give your time for us. Much appreciated, and keep ‘em coming !
    Ps. How about telling us a bit about yourself? You’ve got a lot of fans out there

  5. The main goal is: make it work again….and from a hobbyist point of view, it doesn´t mean much how fast (or not!) you put it back to business, but it mean much that it´s back in biz again 🙂
    That´s the same thing with a restoration….take your time, don´t rush things, but things needs to be done well.
    and you did it well…so what…?!? Congrats, Dave and thank you to make us be able to follow along your repair 🙂

  6. when i need to look up old TTL/CMOS chips datasheets the 1st couple google hits are ususally pdf from old, and lovely, TI datasheet scans converted into .pdf……wired that your search resuslts are so different….

  7. Semiconductores y componentes is Spanish and it means "semiconductors and components" it can be a name of a business or a company. The anrgentinian doesnt exist like a language it is more like a dialect or a speech from Argentina. Btw Hello from northen Spain (Galicia). Good job making this videos and good luck.

  8. Why use the µA range if you're going to short something out? surely the risk of blowing the meter up is much higher in µA range than when using the full A range? Because of burden voltage maybe?

  9. when i first heard the problem i thought: there's gotta be some kind of latching circuit that's switching off the IRLEDs but not switching over to allow the wired setup to work, which relies on that circuit to know when to unlatch the first circuit to switch the IRLEDs on… and i was thinking: bitrot? stuck latch or flip-flop?

  10. Hi Dave, how to make an active ps/2 to USB converter, suitable for old IBM model m keyboards ? like the blue box

  11. LOL, anything that works on batteries should draw zero current unless it's being used. Or else you would have dead batteries in a week.

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