Author Topic: Please help with very old Packard Bell AT/XT Keyboard  (Read 1184 times)

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Offline gerry

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Please help with very old Packard Bell AT/XT Keyboard
« on: Sun, 07 June 2020, 23:21:12 »
Update: Turned out this particular board is just an XT protocol board, with an AT layout and internally-controlled lock lights, and works perfectly but requires a Soarer's converter.

Hello everyone. I acquired a Packard Bell M7US02X keyboard which is apparently a rebranded Korean Sejin M-8700 of sorts. The keyboard seems like it originally had an AT/XT switch which is missing. If I plug the keyboard into a computer (with a passive AT to PS/2 adapter) as-is, I get intermittent flashes of the LEDs, but the computer always reports "No keyboard found" at POST, and will not register any keypresses. One thing I noticed was that I could get the Num Lock to stay on sometimes, but waiting a bit or pushing a key would make it go out. Correct me if I'm wrong, but I think the num lock light somewhat working is an indication that the keyboard is already in AT mode, and at least trying to work, but that's the most I can seem to get out of it.

My first thought was to jump the terminals where the switch used to be to simulate the AT/XT switch, but no combinations of doing that produced any different results, so I followed the traces on the board and realized that two of the terminals for the missing switch lead to places on the board where there seem to be a missing wire and two missing diodes, and the traces just end there and go nowhere. There are also three empty places marked for diodes that are connected closely to the status LEDs.

I have done a LOT of searching and found only a few references to this keyboard's existence let alone any detailed information or schematics. Is there a chance that this one was simply made without these components and intended for only AT or only XT use? Would there be any way to find out without the use of something like a Soarer's converter? I'd prefer not to shell out for one if it won't be a sure thing to get the keyboard working. Maybe something else could be causing the issues? Maybe somebody at some point robbed the keyboard of those missing parts for who knows what reason and putting in new diodes would fix it? It seems bizarre and unlikely to me that someone would remove a switch, some diodes, and a wire from an old keyboard, but the keyboard came from a hoard of stuff left by a relative who was a little... eccentric.

I made an album with pictures showing everything the best I could. Any info would be very much appreciated. I really love the layout of this keyboard and also the feel of the Futaba key switches, so if I can get it working without too much trouble that would be awesome.

https://imgur.com/a/Qz2acy1
« Last Edit: Sun, 02 August 2020, 13:49:34 by gerry »

Online suicidal_orange

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Re: Please help with very old Packard Bell AT/XT Keyboard
« Reply #1 on: Mon, 08 June 2020, 03:25:04 »
Is the motherboard known to work with old boards?  Some new PS/2 ports don't provide as much power as old ones and obviously that would be a problem.

Usually you can tell if something's been removed as there will be solder round the holes.  If the holes are filled that usually means it was machine soldered without that component and if they're clean nothing was ever there.  I'm on mobile so not looked at the pics to see which is the case here.
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Offline yui

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Re: Please help with very old Packard Bell AT/XT Keyboard
« Reply #2 on: Mon, 08 June 2020, 05:29:46 »
The fact that the diodes are not consistent tells me that it tries to initiate and fails, so likely not enough power or maybe a dead keyboard. Seeing the photos to me it would seems to me that nothing was ever soldered there so it is likely permanently AT as XT does not support LEDs on the protocol.
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Offline Tactile

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Re: Please help with very old Packard Bell AT/XT Keyboard
« Reply #3 on: Mon, 08 June 2020, 08:34:54 »
Different revision, probably. I don't think your board is switchable, it's just AT only - which is fine.

I think your problem is most likely related to what appear to be broken traces here...

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Offline gerry

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Re: Please help with very old Packard Bell AT/XT Keyboard
« Reply #4 on: Mon, 08 June 2020, 16:57:22 »
I took another look at it, and that line there is actually raised up a bit, like a bit of excess plastic, and the traces look fine on top of it. It just looks like a crack in the photo because of the way the light was hitting it and causing a shadow. Pretty sure it was just made that way and not the cause of the problem.

Aside from PS/2, I also tried my Belkin and Cube PS/2 to USB adapters, which always worked with Model Ms, and this keyboard just keeps resetting itself repeatedly and I canít get a keypress out of it. Might be a lost cause unfortunately.
« Last Edit: Mon, 08 June 2020, 17:43:19 by gerry »

Offline Maledicted

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Re: Please help with very old Packard Bell AT/XT Keyboard
« Reply #5 on: Tue, 09 June 2020, 11:16:32 »
I took another look at it, and that line there is actually raised up a bit, like a bit of excess plastic, and the traces look fine on top of it. It just looks like a crack in the photo because of the way the light was hitting it and causing a shadow. Pretty sure it was just made that way and not the cause of the problem.

Aside from PS/2, I also tried my Belkin and Cube PS/2 to USB adapters, which always worked with Model Ms, and this keyboard just keeps resetting itself repeatedly and I canít get a keypress out of it. Might be a lost cause unfortunately.

Have you got a powered USB hub to try plugging the adapters into?

Offline gerry

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Re: Please help with very old Packard Bell AT/XT Keyboard
« Reply #6 on: Tue, 09 June 2020, 15:33:18 »
Unfortunately not. Are there any known AT-era boards that draw so much power that they donít work with most USB and PS/2 ports?

Offline Maledicted

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Re: Please help with very old Packard Bell AT/XT Keyboard
« Reply #7 on: Tue, 09 June 2020, 16:19:58 »
I believe that even the Model M has been reported to have problems with that from time to time, from every manufacturer (Though mostly Unicomp's controllers, I believe.) A decent powered USB hub doesn't cost a whole lot, and it can come in handy more often than you might think, for much more than just keyboards. I would at least try it before giving up, unless you've got a whole lot of computers to test with.

Offline gerry

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Re: Please help with very old Packard Bell AT/XT Keyboard
« Reply #8 on: Sun, 02 August 2020, 12:11:43 »
Update in case anyone ever sees this thread again:

I had given up on this keyboard but ended up buying an IBM Model F XT with a Soarer's converter, which I love very much because I'm a buckling springs fan.

However, I finally got around to try this board with the Soarer's, and it instantly worked flawlessly. I am guessing that despite having the AT layout and lock lights, it is actually an XT board in disguise. This keyboard actually feels very nice. It feels like it has less travel compared to the Model F, and while it's a much softer typing experience, these switches are not linear and do have a nice gentle tactility.

I also found further proof that this is in fact an XT board because despite the fact that I am using macOS which doesn't have support for toggling Num Lock, the num lock light comes on and off when I push the key. The Caps Lock light does the same thing despite the fact that I have Caps Lock disabled. So, this is an XT board that turns those lights on and off internally rather than through the computer, since that wouldn't be supported. Mystery solved, I would say, and I'm so glad I held on to this board with the hopes of getting it working someday.

Offline hellothere

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Re: Please help with very old Packard Bell AT/XT Keyboard
« Reply #9 on: Sun, 02 August 2020, 20:41:53 »
I'm new.  Sorry it took too long for me to post regarding this.  Check out https://deskthority.net/wiki/Futaba_MA_series.  Your (well, the same kind of keyboard as yours) is specifically mentioned, and as an XT 'board.