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geekhack Community => Keyboards => Topic started by: kps on Thu, 24 March 2011, 21:00:30

Title: F— F Fault
Post by: kps on Thu, 24 March 2011, 21:00:30

This evening I set out to do a little more work toward adding programmability to the XT to USB adapter (http://geekhack.org/showwiki.php?title=Island:7521), and discovered that my PC Model F is sending copious streams of spurious characters from the lower left region of the keyboard — mostly but not necessarily exclusively F8, F9, F10, Alt, Shift, /, Z, Control, and Q. I now fear I may have accidentally damaged it when I removed it from its case to take pictures (http://geekhack.org/showthread.php?t=16001#post_message_307308) recently. Can anyone offer any insight into this failure?

Title: F— F Fault
Post by: JBert on Mon, 28 March 2011, 15:43:02

If you took it apart, there are a number of possible failure points.

Here's a checklist:

• Are the two halves properly snapped together? Some of the hammers may got stuck beneath the barrel pieces when there was some clearance.
• If you remove the keycaps of the failing keys, can you feel the hammer move when you jiggle the top of the spring?
• If everything moves freely, try holding the keyboard vertical, the long side with two large feet should face down. Now the springs should all fall down as well and make no contact.
• If the last check did it, try holding the keyboard vertical while you put the keycaps back on. The springs might not snapped into place when you added them the first time.

Title: F— F Fault
Post by: Multiple on Tue, 29 March 2011, 09:45:07

So how did it turn out?

I'm with JBert on this one, check the assembly.

Adding to the checklist; is the space bar key cap aligned with and ? If not, the space bar barrel might not be positioned correctly in its socket. If so, there will be an unwanted gap between the two halves. Can you wiggle the black barrels?

Another option that I can think of (because it happened to me...) is water... key caps that are not 100% dry will not only rust your springs but also drop straight down to the capacitive membrane, most water will collect directly under the hammers.

Title: F— F Fault
Post by: kps on Tue, 29 March 2011, 10:18:20

To be clear, I did not disassemble the PC keyboard, beyond removing it from its case. The disassembled keyboard is a different one.

Title: F— F Fault
Post by: JBert on Tue, 29 March 2011, 15:35:03

In that case I'm afraid I can't give any real hints.

I would still recommend to remove some of the keycaps and put them on when holding the keyboard vertical if you did mess around with the keycaps.

If you didn't remove any keycaps and the keyboard worked before opening it up, check if there is no "foreign" stuff in the case which might touch the PCB, it has been reported that even touching the contacts was enough to make the keyboard behave unexpectedly. Checking the earth wire and blue connector might also help.