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Model 1 Keyboard servicing

crock

Experienced Member
Joined
Jan 12, 2012
Messages
285
Location
Zurich, Switzerland
Good evening gentlemen,

I'm been swimming in the Commodore pool for some years now but this is my first dip into the TRS end. What's the water like here, is it warm and inviting to strangers?:surf:

I have got my first TRS-80, so I'm very excited. It's a model-1 with level-II basic and it powers on, so I assume that's not a bad start. Following an old post on this forum, I made up a composite video lead and I now have a picture - even better!

First problem though - 4 keys don't work; 1, O (letter O, not zero), space and enter are all non responsive. Having found the schematics, these are not on the same row or column so I am assuming I'm looking at dirty contacts. SO first question, how easy is it to disassemble the keyboard to clean it? I'm not inclined to take it apart until I know the pitfalls.

Looking forward to hanging out here a bit more.

cheers, Rob
 
Rob, I too have recently acquired a TRS-80 model 1 and have keyboard issues. The key switches appear to be old ALPS T type key switches that nobody makes anymore. Web site "Nightfallcrew.com" mentions cleaning of key switches but does not go into much detail. I am in need of three such switches as the shaft on mine were broken off so if you find any please let me know.img_2560.jpg

Thanks, Charles
 
Rob,
Years ago, if my memory serves me correctly, I removed the circuit board from my Model 1, and cleaned the key's pads, and circuit board with
cotton swabs and Alcohol. It fixed my problem of not getting the input from certain keys.

I also added the Lower Case (LC) Modification to my Model 1, and I updated the ROMS to the latest Model 1 ROMS by using EPROMS I programmed.

Larry
 
If it's the original style keyboard just need to clean the contacts.

Take a big paper clip. The strong ones. Straighten out one lead and form a hook on the end.

Put hook under the keycap and pull straight up by corner supporting opposite corner with finger.

Look inside key and you will see 2 contacts that are separated by a white piece of plastic.

Now when you push the key down the 2 metal contacts should touch each other.

If you have this type of keyboard then spray a little bit of WD-40 inside and push up and down a few times to work in the WD-40.

Test key by leaving off key cap and turning on TRS-80. See if the key in question is working or not. Hopefully it will be now. If so repeat for other keys.

That's how I got my keys to work. Hope this helps.

OH yes the spacebar may be a bit tricky to get off but it's done the same way.

If it's the newer type do what ldkraemer mentions above in which case I am not sure.
 
My keyboard doesn't really sound like either of these. I found this article that mentions repairing a model 1 keyboard appears to be the same model as mine. He also has some pictures of the keys after removing them from the keyboard PCB.

The keys are mechanical switches which are individually soldered to the PCB. To remove them you have to desolder the 2 contacts before popping the mechanism out of the top of the metal keyboard chassis. You can then dismantle the switch mechanism by gently prying the plastic clips apart. You can then see the insides as pictured here and here.

So far, of the 5 switches that were faulty I have managed to restore 4 to normal operation. For most, I was able to spray the insides with contact cleaner and using a piece of dental floss to clean underneath the contact. I then rinsed all the parts in isopropyl alcohol before drying and reassembly. The exception was the one from the space bar which had obviously seen a lot of use. For this the contacts were not making a connection when the key was pressed and the part of the key assembly that contains the contact was not well fixed in the housing, as seen in the second image above.

I think I should be able to restore this by wedging the whole assembly further forward, perhaps with a peice of paper. We shall see...

regards, Rob
 
Were the contacts kind of J shaped when viewed from the side? If so then try my method. It's a lot less easier. Just pop off on key and see if it's like I described.
 
Were the contacts kind of J shaped when viewed from the side? If so then try my method. It's a lot less easier. Just pop off on key and see if it's like I described.
I don't think so, no. I can not see any way you could service the keys without desoldering the mechanism from the PCB. If you follow the links in my previous post, you can see exactly what the insides of my keys look like.

Rob
 
I don't think so, no. I can not see any way you could service the keys without desoldering the mechanism from the PCB. If you follow the links in my previous post, you can see exactly what the insides of my keys look like.

Rob
Odd...
I have some of these Alps keyswitches; the connecting pins are offset to one side and in line with the flat of the stem, just like the picture of the disassembled one, but the empty position in that keyboard picture shows the pins in the centre at 90 degrees to the stem. What's up with that?

Even if it's rotated like the one above it the pins would still be in the wrong place, no?

Edit: just had a look at a keyboard that uses these switches and it looks like for some reason all the wide keys' switches are rotated 90 degrees so that explains the orientation, but the holes in the picture are still round and centered instead of flat and offset...

Anyway, Rob, I take it you have things under control and don't need any replacements?
 
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...but the empty position in that keyboard picture shows the pins in the centre at 90 degrees to the stem. What's up with that?
Hey Mike - I think that's the return key, which is indeed rotated through 90 degrees as its mounted on the PCB as well.
Anyway, Rob, I take it you have things under control and don't need any replacements?
Hopefully not, but need is not the same as 'would like'. ;)

I managed to grab 30 minutes before I left for work this morning in which I tested the 'small peice of paper' kludge and I'm hopeful it will work. I won't know for sure until I reassemble everything this evening.

Rob
 
Hey Mike - I think that's the return key, which is indeed rotated through 90 degrees as its mounted on the PCB as well.
Yes, I did notice that all the wide keys are rotated, but the pin holes still look odd; oh well...

I managed to grab 30 minutes before I left for work this morning in which I tested the 'small peice of paper' kludge and I'm hopeful it will work. I won't know for sure until I reassemble everything this evening.
If the problem is that the switch assembly is loose then shimming it up towards the plunger should work; good luck!

I disassembled one of mine and it looks a little different from yours (maybe an improved version?); the switch assembly is pretty firmly inserted in a groove in the upper half of the housing so it's certainly not going to flop around, and it looks like you could separate the 'sandwich' just enough at the pin end to squirt some contact cleaner inside or even burnish the contacts with a piece of paper:

Alps1.JPG Alps2.JPG

These are genuine Alps switches BTW; I gather that there are "simplified ALPS copies" out there:

http://hothardware.com/cs/blogs/mrt...hanical-key-switch-keyboards-demystified.aspx
 
Ok that's totally different than what mine was. Sorry Rob for any confusion on my part. Good luck.
Hey, that's no problem. Well meaning advice that's not needed by me today could save someone else tomorrow.

The good news is that all my keys are now working. Yay!

I am now the proud owner of a 16k model 1 with level 2 basic. Now to find something to run on it...

Rob
 
Wow I finally looked at the article and that is definitely a later keyboard revision than mine had.

Well now find a Cassette cable and a cassette player for it and get some cassette software and have fun. Or type in programs
yourself in BASIC. Or better yet get an Expansion Interface and Floppy drives. That's when the real fun begins!
 
Wow I finally looked at the article and that is definitely a later keyboard revision than mine had.

Well now find a Cassette cable and a cassette player for it and get some cassette software and have fun. Or type in programs
yourself in BASIC. Or better yet get an Expansion Interface and Floppy drives. That's when the real fun begins!
Thanks!

I'm doing a talk next week about the history of the home computer and now I'm looking for something I can leave running on it while I am talking? Either some kind of rolling display or a game I can leave running?

cheers, Rob
 
One of the October issues of "80 Micro" had a type-in program to create a "talking jack-o-lantern" which moved its mouth in sync with sound input via the cassette jack. Look for that and let the Model I talk along with you. ;)

(I set up a monitor in the window hooked to the Model I with that... many, many, *many* moons ago. The program itself was an interesting demonstration of doing fast animation with BASIC string packing.)
 
Hi Rob
just an idea for your talk, if you check-out the June2012 edition of TRS8BIT at trs-80.org.uk, there are a numer of 'one-liner' programs which are easy and quick to type in. For continous running, try the Pi, mirror images and circles programs. Hope this helps (Snail run is my favourite!)

regards
Dusty
 
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