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PC Keyboard not functioning ?

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123434
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Posts: 99
Joined: Wed Dec 18, 2013 7:16 am
Location: Vassa, Finland

PC Keyboard not functioning ?

#1 Post by 123434 » Sun Jan 07, 2018 5:53 am

Hello ( PC Keyboard not functioning ? )
This external keyboard(with trackball) is from a 1998 programming notebook PC. (Siemens PG720P1)
- Num lock-led flashes at startup for a while but leds shutdown in windows. No buttons work.
- It worked earlier but after storage it has now stopped working...
Could anyone check from photos below if it has for example a notable defect somewhere in the circuitry ?
Anyway to fix ?
I tried cleaning with alcohol but no effect. It worked perfectly 2 years ago but now it has stopped working...
- It seems to not have any big conductors that leak/dry as in many "fix keyboard guides".

http://s162.photobucket.com/user/123113 ... 9.jpg.html
http://s162.photobucket.com/user/123113 ... c.jpg.html
http://s162.photobucket.com/user/123113 ... e.jpg.html
http://s162.photobucket.com/user/123113 ... v.jpg.html

123434
Freshman Member
Posts: 99
Joined: Wed Dec 18, 2013 7:16 am
Location: Vassa, Finland

Re: PC Keyboard not functioning ?

#2 Post by 123434 » Sun Jan 07, 2018 11:36 am

I saw a youtube video that suggested using rubber or steel wire on oxidized connectors. I try that.
- Many connectors looks like copper and brown colored and they seem to turn to silver colored when rubber is used.
These keyboard are really picky and fraqile. Hope this rubbering helps.

thinkpadcollection
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Location: kingston, ontario, Canada

Re: PC Keyboard not functioning ?

#3 Post by thinkpadcollection » Sun Jan 07, 2018 4:11 pm

This is dreaded unfixable design. The microcontroller is in this black blob on the flexible circuit board. Any components affixed to the flex circuit is done with conductive glue on yet another conductive printed on traces and they always crack if flexed too much. I lost a new keyboard to this but cost was not too bad, 15 CDN so ordered another and next time get a latitude 3340/3350 motherboard this is what causing the problem in first place. I broke the keyboard by fussing with too much cracked the printed on traces. Also do not attempt to solder, if you manage to find a crack, use conductive paint made for this.

Go really gently if you are trying to work on this type and also trying to clean the keyboard key contacts but this is nothing you can do if the LEDs goes out on boot up. Tried different USB to PS/2 adapter or different OS just in case if windows is the problem? Also use very mild chemical cleaner, alcohol only.

Cheers, thinkpadcollection

123434
Freshman Member
Posts: 99
Joined: Wed Dec 18, 2013 7:16 am
Location: Vassa, Finland

Re: PC Keyboard not functioning ?

#4 Post by 123434 » Mon Jan 08, 2018 12:40 am

Hello so it is "the golden spider with black blob" that is faulty ?
I saw that some of those tiny golden legs(about 4/50pcs legs) are a bit lose. I tried to use a regular tape to attach them. After it I think some of the LEDs came up more visible at start up but it is still not working.

If it should work the NumLock-LED should stay ON at start up but it does not.
Storage temperature changes might have detached those glued copper legs.

What is the name brand of the good original quality conductive glue ?
Is it same thing as quick glue with some conductive material included ?
-> Is it possible to glue the black blob's legs with hand and a microscope ?

I'm now using a basic PS/2 keyboard as a replacement but it is not the same feeling because the size is larger.

Do someone offer or make similar basic flexcircuit boards(without trackball) so I could just swap it in ? I'll use the same plastic casing/buttons and swap the flexcircuit.
Siemens Nixdorf PG720p ( I version 1998 ) Germany
- It's an external keyboard from a Siemens laptop/All-in-one PC. AMD K6 233 Mhz little foot socket 7. EDO ram 5V 72-pin so-dimm.
https://www.google.fi/search?q=pg720p&c ... 68&bih=562

123434
Freshman Member
Posts: 99
Joined: Wed Dec 18, 2013 7:16 am
Location: Vassa, Finland

Re: PC Keyboard not functioning ?

#5 Post by 123434 » Tue Jan 09, 2018 1:49 am

Has anyone taken apart a new external mechanical keyboard with separate switches for each key and transplanted it inside to an old vintage membrane-style keyboard's shell ?
( I have now a vintage white colored external keyboard shell with pristine-buttons and all but inside electronics are broken)

Is it easy and possible ? I would want this to work. So far choices are...
1.) Buy conducting silver paint and try to fix the old circuit with stereoscope/microscope.
or
2.) Transplant a new mechanical keyboard's switches to this old membrane printed circuit keyboard.

thinkpadcollection
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Posts: 802
Joined: Fri Oct 17, 2014 8:13 pm
Location: kingston, ontario, Canada

Re: PC Keyboard not functioning ?

#6 Post by thinkpadcollection » Tue Jan 09, 2018 3:36 am

I do not know why about this keyboard problem, and could be good or faulty, need to carefully check the computer, sometimes LED goes out during the boot up which is normal unless knew this machine well and in bios settings make number lock LED lit as disabled or enabled? Do not work with this keyboard too much since keyboard connectors, silkscreened traces and glued electrical for components connections break easily if handled too much. Also LED if lit, it could be still good as they are commanded by bios during start up communicates with keyboard microcontroller and in turn responds to bios otherwise computer will say keyboard faulty like a computer with disconnected keyboard or fuse blown complaining about keyboard missing.

Cheers, thinkpadcollection

olex126
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Posts: 197
Joined: Tue May 29, 2007 3:46 pm
Location: St.Thomas, Ontario, CANADA

Re: PC Keyboard not functioning ?

#7 Post by olex126 » Tue Jan 09, 2018 5:00 am

FWIW...

For conductive glue, try the metallic cement that comes with a car rear-defroster repair kit.

I've used it a couple of times to repair different electrical circuits.

Regards.

Dave
Previous Thinkpads: 701C A22m A30/A31p T23p x2 T30 T41 X31 various 750's 760's & 390's.

Current Daily Drivers: Various X60T & X61T's, various T42p-T43p's, x200 x201 x220 x230 W520 T601F LED (T9500/8Gb/250SSD/W7 Ultimate)


"Life Is A Journey...Enjoy The Ride!"

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