Vintage KB's light keep blinking

[Desi]

Hiya,

A month or so ago I rescued an NTC 6251EA from a giant stack of keyboards at the op shop, one so old that it has an AT cord and a switch at the back for 8088 and 80286 compatibility. While I was waiting for my Blue Cube to arrive from ClickyKeyboards, I cleaned it up and replaced the AT cord with a PS/2 cord, making sure to double-check the pin connections. My mobo is an ASUS P8P67 Deluxe r3, hence the Blue Cube.

I received my Blue Cube about an hour ago and connected the keyboard to my computer. The keyboard lights blinked once, but NumLock didn't stay on and the computer wasn't receiving any keystrokes.

I checked the switch at the back and found it was on 80286, so I flicked it to 8088 and tried again from soft and hard reboots. Now all of the lights blink continually and in unison every second, but the computer is still not receiving any keystrokes. When I hold down NumLock the light stays on while the others continue blinking, and releasing NumLock just makes the NumLock light continue blinking with the others.

Googling didn't turn up much (seems this problem happens to other people when the BIOS or CMOS mess up, but my computer is fine). Has anyone encountered this in any other vintage keyboard? Is this one of those situations where the resistor mod would work? Is this a sign of a malfunctioning keyboard?

[mr626]

Have you tried using it with the original AT cord and a AT -> ps/2 adaptor?

I had a very similar NTC keyboard that had the 8088/80286 switch, and it worked fine via a AT -> ps/2 adaptor and having the switch on 8088

[Desi]

I haven't, since I've had a ton of trouble actually sourcing one in Australia. I'll order one now, though.

I had a look at the PCB and noticed the clock pin's soldering was cracked, but resoldering it didn't fix the issue. =(

EDIT: I just tried connecting it directly to the mobo via the replaced PS/2 cord (with no other keyboards connected). The lights did the usual POST blinking thing, which gave me hope, but then the BIOS told me that no keyboard was detected, and the keyboard continued to be ignored by Win 7. Pressing NumLock or Caps Lock made the lights come on, but pressing them again didn't make the lights turn off, which seems like a communication problem — this IS a mobo listed as problematic on the Geekhack wiki.

[mr626]

There's plenty on ebay:

http://www.ebay.com.au/sch/i.html?_trkparms=65%253A12%257C66%253A2%257C39%253A1%257C72%253A5523&rt=nc&_nkw=at+ps2&_dmpt=AU_PC_Video_Games_Games&_sticky=1&_trksid=p3286.c0.m14&_sop=15&_sc=1

Sounds like fixing it might be more trouble than its worth :-(

[Desi]

Yeah it's starting to seem that way. I just tried connecting it to an older PC, and it's got the same flashing light dealy. I'm going to try it on Ubuntu now, and if it doesn't work then it'll just be a write-off I guess.

The upside being that now I have a Blue Cube all ready for that magical day when I find a Model M in a secondhand store. :rockon:

UPDATE: Nope, aside from being able to turn off the Num Lock light by pressing the button again, the blinky lights and no received keystrokes problem is still present in Ubuntu. That this happens across two different operating systems means that it is a hardware issue, which I'm not really knowledgeable enough to spend the time tackling. Looks like I have to be all mainstream and buy a modern mechanical keyboard like a regular person. =(

Thanks for your help! I'll post on the It's In The Mail board when I pick one.

[mr626]

Ah, tough luck. Sorry to hear its dead. Out of interest what kind of switches did it have? My NTC had white ALPS

I wouldn't give up on finding a vintage mechanical. Op shops are a good starting point. As per my sig I've been able to find some older mech boards on my travels and I'm from Australia, so it can be done. The Model M is the challenge though- took me almost 5 months to find mine.

[Desi]

Yup, this one also had white ALPS. Lovely clicky sound too, it's a real shame.

Of course I'll still be looking around for mechanicals (even if they don't work, it's fun to restore them), but meanwhile I've ordered a Leopold with Cherry Browns. It's getting the boot if I find a Model M, though. =D

[mich]

I believe this switch toggles between XT and AT modes (IBM PC XT had 8088 CPU, PC AT had 80286) and you have set it wrong. If it was set to AT mode (as it should be set to work with PS/2), then either all keys would work or you wouldn't be able to toggle numlock on/off, because in AT mode leds are controlled by software and hence they can't light up if the computer doesn't receive keypresses. Simultaneous blinking of all leds is probably the keyboard's reaction to PS/2 port trying to talk to it in ways in which an XT computer wouldn't.

Did you try the 80286 mode without USB adapter?

[Desi]

I did try 80286 mode both with the Blue Cube and straight into the PS/2 port. Both cases resulted in no lights turning on, and no received input from the keyboard. =( Same thing in both Windows 7 and an Ubuntu Live CD.

[hawkwind]

http://www.amazon.com/Belkin-F2N017-Keyboard-Adapter-MiniDin6/dp/B00000J1UB/ - Works for all my AT boards including a NTC KB-6251EN. Board has simplfied ALPS with a plastic plate which makes it bloody loud. Goodluck finding a Model M in AUS.

[Desi]

Thanks, but I've already placed the order for that Leopold. I'll bookmark that link, though, because that's the only Belkin AT/PS2 I've seen that ships to Australia at all. Sure to come in handy!

And yeah, I'm not getting my hopes up for a Model M in Western Sydney. =P

[mich]

In Ubuntu, it should be possible to disable keyboard driver and dump all data received on the PS/2 port:

Code: [Select]

root@sauron:/home/m # echo -n serio_raw >/sys/bus/serio/devices/serio0/drvctl      # This enables raw access to PS/2 keyboard port.
root@sauron:/home/m # cat /dev/serio_raw0 |hexdump -e '1/1 "%x\n"'                 # This will print all (if any) bytes received on this port.
39             # this appeared when I hit some keys on my keyboard
f0
39
29
f0
29
^C             # CTRL+C terminates catNormally "serio0" and "serio_raw0" will correspond to keyboard port and "serio1", "serio_raw1" to mouse port. If your mobo has only one dual-purpose PS/2 port and "serio0" doesn't work, try "serio1". If you get some output, post it here. If not, the connection between computer and keyboard must be dead. Check again if clock and data lines are wired correctly. Check if there is a constant +5V voltage on them. Try the resistor mod, adding something like 2.2k or 4.7k shouldn't hurt.

[mr626]

And yeah, I'm not getting my hopes up for a Model M in Western Sydney. =P

As I said, don't give up hope. My Model M came from Western Sydney as it happens.

[Desi]

In Ubuntu, it should be possible to disable keyboard driver and dump all data received on the PS/2 port:
Check again if clock and data lines are wired correctly. Check if there is a constant +5V voltage on them.

Hmmm I'll try this when I get home.

[mich]

I think there is one more thing worth trying: if the keyboard is able to receive commands, this will reset it and make all leds flash for a moment:

Code: [Select]

echo -ne '\xff' >/dev/serio_raw0

[Desi]

Okay, I've tried both those things in Ubuntu. Connecting the keyboard to the PS/2 port and trying to capture both serio0/serio_raw0 and serio1/serio_raw1 (my mobo has a combination port) resulted in nothing being captured. Tried it in both 8088 and 80286 mode to no effect. Trying to reset serio_raw0 and serio_raw1 resulted in no lights blinking. In all cases, Ubuntu reported no device connected.

I pulled out the multimeter and checked the voltage between each pin and the nearest connecting component, and the voltages were nowhere near 5V and fluctuated constantly, and this occurred regardless of direct PS/2 connection or connection through the Blue Cube:

Via PS/2 port — Fluctuated between 0V and 0.15V, no lights flashing (80286 mode), or 0V and 0.20V, no lights flashing (8088 mode).
Via Blue Cube — Fluctuated between 0V and 0.20V, no lights flashing (80286 mode), or 0V and 0.50V, lights flashing (8088 mode).

All of the pins are wired properly, and the replacement PS/2 cord I used has negligible resistance and is uninterrupted along its length. I also checked the soldering over the whole PCB yesterday and found and resoldered a cracked joint, so that shouldn't be a problem.

[mich]

I pulled out the multimeter and checked the voltage between each pin and the nearest connecting component

I'm not sure what you mean by "nearest connecting component". It should be 5V between ground and data and 5V between ground and clock (and, obviously, 5V between ground and vcc).

0.2V between ground and data is definitely a failure somewhere in the keyboard - try to find out what exactly is connected to data pin (probably a pull-up resistor and either the microcontroller or some other chip, but maybe something else).