Model III Keyboard Woes

Model III Keyboard Woes

Post by Bob Steh » Thu, 18 Apr 2002 13:00:09



I have a problem with a Model III keyboard.   The letter "s" has died -
it wont type, the rest of the keys work fine.   I have had the keyboard
out and cleaned it with compressd air but that did not help I sprayed
the "S" key with CRC and that worked for about 10 minutes.   Does anyony
know of a fix that will work for a little longer please.

--
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG

 
 
 

Model III Keyboard Woes

Post by Mike Yetsk » Thu, 18 Apr 2002 23:00:04


If it's one key out, and nothing else in the 'row' or 'column' of the
keyboard
matrix, it's the key.

Sometimes, although not that often, the key could have a bad solder
joint.  Mostly because of corrosion on the key when it was soldered in,
and it could have 'broken free'.  If you're good at soldering, you can take
the keyboard out and try to resolder just that key.  When you do, look
for the solder flowing smoothly and 'wetting' the contacts and the pads.
If not, then it's probably a contamination issue, and you might be able
to easily fix it with some cleaner or liquid flux.

If that doesn't fix it, then you need to replace that particular key, which
is
the more likely failure mode.

Mike


Quote:> I have a problem with a Model III keyboard.   The letter "s" has died -
> it wont type, the rest of the keys work fine.   I have had the keyboard
> out and cleaned it with compressd air but that did not help I sprayed
> the "S" key with CRC and that worked for about 10 minutes.   Does anyony
> know of a fix that will work for a little longer please.

> --
> Posted via Mailgate.ORG Server - http://www.Mailgate.ORG


 
 
 

Model III Keyboard Woes

Post by David J. Pittell » Fri, 19 Apr 2002 14:18:43


Bob:

As Mike has mentioned, its the keyswitch for the "S" key that needs to be
replaced.

(1) See if someone who reads this newsgroup is nice enough to desolder a
good keyswitch from a extra keyboard they might have and mail it for a small
fee.
I am guessing this keyboard is an ALPS keyboard, with 2 solder connections
per switch?
(2) You could desolder the switch and try to disassemble it and see if you
can fix it, I am not sure how much luck you will have on your first try?
(3) You could simply swap the "S" keyswitch with a keyswitch  that is rarely
used - possibly from the keypad?

While thinking about this .... I was trying to remember who made keyboards
for the older TRS-80 products. Help me here ..... my memory is failing :)

Model I:

Original keyboards made bi HITEK, these were the keyboards that KBFIX was
written for. These keyboards had replaceable contacts and a special tool
used to insert the replacement contacts. (after desoldering the old ones and
pulling them out with needle nose pliers!) Oh yes, Shiny keycaps and were
frequently cleaned by customers with contact cleaner spray.

ALPS made the next generation keyboards, discreet keyswitches.  Very nice !

Model II:

Early keyboards made by Cherry, kinda sensitive .... not many of these.

A couple of different revisions of  keyboards made by KEYTRONIC. Lots of
little screws and little foam pads.

Model 16:

Same as the late generation Model II keyboards (KEYTRONIC) - different white
and black keys instead of gray and black.

Model III:

Original keyboard made by ALPS, using the same basic style keyswitches as
the late generation Model I keyboard.

I can think of at least one other style Model III keyboard, I don't remember
if ALPS made the switches - these switches had (4) connections - they were
SPST switches each side of the switch simply had 2 connections, if you saw
the board  layout you would see why this was done.

Model 4:

I am pretty sure the later style Model III keyboard keyswitch was used in
the original Model 4.  (obviously a few more keys!)

Do I correctly remember a version of the Model 4 keyboard that didn't use
discreet keyswitches? ?? 4D?

Model 4p:

Did Fujitisu make these??

Model 12 / 16B:

I can only remember KEYTRONIC keyboards, possibly a few slightly different
revisions?

Model 6000:

Never took one apart, did Fujitsu make these?

Tandy 2000 / 1000 / 1000SX / 1000EX / 1000HX (did I miss some that had a
Fujitsu keyboard)

These were Fujitsu keyboards. I really liked these! They had 12 function
keys when IBM only had 10!

I am pretty sure the "Tandy Enhanced Keyboard" with the Enhanced AT keyboard
layout (101 keys?) was made by Fujitsu also.

Coco:

Is this getting out of hand??

I can remember at least 4 or 5 versions .... can even remember doing the
6821 to 6822 swap and mods to the original Coco to install the enhanced
keyboard!

Thanks for letting me ramble .... I miss the good old days!!

Davep


Quote:> If it's one key out, and nothing else in the 'row' or 'column' of the
> keyboard
> matrix, it's the key.

> SNIP

 
 
 

Model III Keyboard Woes

Post by FreeSpiri » Sat, 20 Apr 2002 04:12:14


I had a model 4 and a 4p. I still have the 4p and it works flawlessly
but I trouble with the keyboard in the model 4. It had switches with the
4 contacts. Inside the switches there was a * button with a very
thin coating of a conductive material which made contact across two
contacts when pushed. Cleaning didn't help as I guess the coating wore
off. Someone here sugested that they used to sell a paint on liquid to
replace the conductive coating but I was never able to find any. I ended
up replacing the switches from the keypad as it was rarely used anyway.
The model 4 is now in a computer museum and isn't used anymore anyway. I
don't know who manufactured the keyboard though.

Good luck with yours :-)

Andy

 
 
 

Model III Keyboard Woes

Post by Sylvan Butle » Sat, 20 Apr 2002 07:46:50



> thin coating of a conductive material which made contact across two
> contacts when pushed. Cleaning didn't help as I guess the coating wore
> off. Someone here sugested that they used to sell a paint on liquid to
> replace the conductive coating but I was never able to find any. I ended

* keypad repair, usually used for remote controls.  not cheap.
http://www.veryComputer.com/

sdb
--
 | Sylvan Butler | Not speaking for Hewlett-Packard | sbutler-boi.hp.com |

    They that can give up essential liberty to obtain a little temporary
    safety deserve neither liberty nor safety. --Benjamin Franklin, 1759
 Fight terrorism, arm the population!

 
 
 

Model III Keyboard Woes

Post by Rick » Sat, 20 Apr 2002 16:26:48




> > thin coating of a conductive material which made contact across two
> > contacts when pushed. Cleaning didn't help as I guess the coating wore
> > off. Someone here sugested that they used to sell a paint on liquid to
> > replace the conductive coating but I was never able to find any.

More like an epoxy, actually. Once mixed you have to use it or lose it.

Quote:> I ended

> * keypad repair, usually used for remote controls.  not cheap.
> http://www.veryComputer.com/

> sdb
> --

Smaller, lot less expensive kits of the same stuff:

http://www.veryComputer.com/

CW2605 for 50+ contacts $8.49
CW2610 for 200+ contacts $22.95

Did these keyboards really use conductive carbon contacts? Seems like pretty new
technology for this vintage computer. (In it's day...)

 
 
 

Model III Keyboard Woes

Post by Sylvan Butle » Sun, 21 Apr 2002 02:46:20



> Smaller, lot less expensive kits of the same stuff:

> http://www.veryComputer.com/

Ahh, yes.  Should have remembered Hosfelt.  Usually cheaper S&H than
MCM also!

Quote:> Did these keyboards really use conductive carbon contacts? Seems like pretty new
> technology for this vintage computer. (In it's day...)

1978-80?  Sure, using conductive carbon buttons dates from the
original carbon microphone days in the 1800's. Don't know when it
first appeared in a keypad type contact though...  :)

BTW, another EXCELLENT repair, maybe even cheaper when you consider
the waste with infrequent repairs of small quantities, is to get a
bit of gold leaf.  Clean the carbon off the * button and press
on a bit of gold leaf, working it into the surface of the *.
I've not done this personally, but reportedly it works great.  Gold
leaf (get the REAL stuff!) is available from many craft suppliers.

I have glued dots of aluminum foil over the * button, but I
cannot recommend that method.  It does work, for a time.

Another source with some interesting info re. the repair kits:
  http://www.veryComputer.com/

sdb

--
 | Sylvan Butler | Not speaking for Hewlett-Packard | sbutler-boi.hp.com |

    They that can give up essential liberty to obtain a little temporary
    safety deserve neither liberty nor safety. --Benjamin Franklin, 1759
 Fight terrorism, arm the population!

 
 
 

Model III Keyboard Woes

Post by jim korma » Sun, 21 Apr 2002 06:51:49




>>Smaller, lot less expensive kits of the same stuff:

>>http://www.veryComputer.com/

> Ahh, yes.  Should have remembered Hosfelt.  Usually cheaper S&H than
> MCM also!

>>Did these keyboards really use conductive carbon contacts? Seems like pretty new
>>technology for this vintage computer. (In it's day...)

> 1978-80?  Sure, using conductive carbon buttons dates from the
> original carbon microphone days in the 1800's. Don't know when it
> first appeared in a keypad type contact though...  :)

> BTW, another EXCELLENT repair, maybe even cheaper when you consider
> the waste with infrequent repairs of small quantities, is to get a
> bit of gold leaf.  Clean the carbon off the * button and press
> on a bit of gold leaf, working it into the surface of the *.
> I've not done this personally, but reportedly it works great.  Gold
> leaf (get the REAL stuff!) is available from many craft suppliers.

> I have glued dots of aluminum foil over the * button, but I
> cannot recommend that method.  It does work, for a time.

> Another source with some interesting info re. the repair kits:
>   http://www.veryComputer.com/

> sdb

I recall an article (early 70's) on how to build a keyboard using
conductive foam. Radio Electronic I think.

Jim

 
 
 

Model III Keyboard Woes

Post by Michae » Sun, 21 Apr 2002 20:09:24


I had the same problem with a Model I, III and IV.  The best way to fix
it is to replace the key.  It's not difficult.  If you can solder then you
can
fix it.  I fixed numerous keys in the TRS-80 Models.  A couple of spare
keyboards from bad systems are good to have around.  The model 4P
is a totally different keyboard and the keys will not work with the I,
III or IV.

Mike


Quote:> I have a problem with a Model III keyboard.   The letter "s" has died -
> it wont type, the rest of the keys work fine.   I have had the keyboard
> out and cleaned it with compressd air but that did not help I sprayed
> the "S" key with CRC and that worked for about 10 minutes.   Does anyony
> know of a fix that will work for a little longer please.

> --
> Posted via Mailgate.ORG Server - http://www.Mailgate.ORG

 
 
 

Model III Keyboard Woes

Post by Leonard Erickso » Wed, 24 Apr 2002 09:46:42



>If it's one key out, and nothing else in the 'row' or 'column' of the
>keyboard
>matrix, it's the key.

>Sometimes, although not that often, the key could have a bad solder
>joint.  Mostly because of corrosion on the key when it was soldered in,
>and it could have 'broken free'.  If you're good at soldering, you can take
>the keyboard out and try to resolder just that key.  When you do, look
>for the solder flowing smoothly and 'wetting' the contacts and the pads.
>If not, then it's probably a contamination issue, and you might be able
>to easily fix it with some cleaner or liquid flux.

>If that doesn't fix it, then you need to replace that particular key, which
>is the more likely failure mode.

*Some* types of key used for Model III keyboards could be disassembled
if you were careful. Cleaning them inside could fix them too. As well as
rebending "spring" strips.

But this requires desoldering the key and isn't worth the hassle unless
you can't get a replacement.

--
Leonard Erickson (aka shadow{G})


 
 
 

1. WANTED: Model III keyboard matrix

Hi,

I have been looking for the schematic on the keyboard matrix for a
TRS-80 Model III. In my computer the numeric keypad '3' key and the
'up arrow' key don't work. I have taken the computer apart and cleaned
everything inside, the keyboard was removed and then all solder points
reheated to flush out any cold solder joints of flux contaminated
ones.

Have looked in quiet a few places in the web for the matrix to no
avail.

Thanks for your help in advance!

-=-=-=-
Rogelio

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