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newTIboyRob

stubborn FCTN key

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Does anyone know of any other way to print a " mark on the screen when entering a basic line number?  My FCTN key isn't working and thus not enabling me to.

 

Thanks

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thanks... but now I learned of another issue... the damn space bar doesn't work either.  Everything else does!

Looks like I have to open her up?  Is it a hard thing to fix?

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I had the same problem, after pulling my TI out of the closet where it had set for 20 years.

Most likely problems no contact when key is pushed down.

The fix can be easy if you have an old style keyboard.

   Take off the key cap, take some contact cleaner on a piece of paper, slip it between the two pray-mantis hands - push down on the key, pull the paper with the contact cleaner out. Repeat several times. If it's a newer style keyboard with a Mylar back it may require soldering and or drawing new traces.

   I was that guy, who pulled all of his black keyboards out and replaced them with keyboards from radio shack, because I liked the feel better, woe be unst me, 40 years later....

d.

 

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Yes, this keyboard too has not been used in quite some time, and I had the same suspicion as you did- that the most likely problem is no contact is being made. It looked like that, seemed like that... even kind of felt like that, far away.

Thanks for your method, just some questions, as I am definitely not technical:

 

key cap = ?

if I don't have contact cleaner, any other substitute that can be used?

the two pray-mantis hands ... = ?

 

And imagine now... no brick and mortar Radio Shack stores either.  My how the world hath changed!

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I learned some very interesting things in your advice to search stackpole, mylar, and the differences between them- how the early keyboards were stackpole blocks with connector switches and the later versions had that mylar sheet.

Before actually venturing into opening up the keyboard, I am wondering if I maybe have the stackpole/switch version, because only 2 keys are not working, the space bar and the FCTN key.... but I was able to get a " to work by kind of pressing at a different angle/side of the key.

 

Based on this, what would be your guess on the keyboard style?

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I've had a couple of the solder joints fail on the contact-type keys. Easy to see once the TI's bottom cover is removed. Cleaning contacts from above didn't help of course. Close inspection of the keyboard circuit board at the location of the bad key showed that one or both of the switch's pins had broken free around the pad. A little fresh solder applied with a low-wattage soldering iron cured it.

-Ed

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I told you all.... We should have bought the extended warranty! 😃

For cleaning, either CRC or Deoxit seems to be favorites.

so to sum up... Work the tops if you can. I used old business cards to clean contacts and GROM ports, thne if you have to remove just the bottom and reflow just the bad keys with new solder.

 

I've used: MG Chemicals 8341 No Clean Flux Paste - it does a very good job of making solder flow on older connections.

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For the keys that have the leaf-spring fingers that come together to make-or-break the connection, any sort of *light* abrasion should do the trick.  You only need to clean off 30 years of contact tarnish or build-up on the metal contacts.  Try pushing a small screwdriver between the contacts a few times.  Also, a lot of key-switches have a very small amount of grease that lets them operate smoothly, and going crazy with a cleaner of some sort can lead to keys that don't seem to work as smoothly as they did before because you have washed away the lubrication.

 

I have inadvertently done this on multiple occasions where I go overboard on a restoration, pull all the keys, wash them in soap and water, hyper-clean the PCB and other mechanical parts, then reassemble.  In some cases I had to go back and re-lubricate the keys, especially the ones with the metal supports under the larger keys, like space-bar keys.

 

Also, as mentioned above, check for broken or cold solder joints.  These keyboards are not very well made, and the mechanical vibration from pushing keys can transfer to the solder connections, which can break them after such a long time.  And like any mechanical system, the longer they sit without being used, the worse they will be.  The best thing for a keyboard is to be used regularly.

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before I even start to do anything, it just feels like the space bar isn't making any contact at all with the circuitry inside underneath. From looking at the keyboard outside, it just seems like the space bar is too far away from the main block of electronics underneath and inside, so when it is pressed down it is not making any contact.  (The FCTN key seems like it has more of a chance of working since I did see a quotation mark once after like every 100 strokes.)  Those are the only 2 issues with it, as the rest of the keys work fine.  

 

If I unscrew the bottom and look inside, are we saying that I'd see a break/separation in the circuitry path near the space bar area?  (I don't know what I am looking for since I have never done this!) 

In laymen's terms, the space bar and FCTN keys would look different than the other pathways?   

 

I don't see how just taking off the key caps and cleaning the connections is going to resolve this, and maybe I have to just be brave open it up?   Bear in mind too that I have neither the tools nor the knowledge of soldering :(

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Last time I had to open mine up for just this reason, I kinda brought it on myself. When the Function and a Shift key got balky, my first response was to bang the key a bunch of times. That worked for awhile but got worse. The next weapon I deployed was a shot of cleaner on a narrow strip of cardstock. I stuck it between the contacts, activated the key by pressing down on the post and pulling out the cardstock. You could see the grime it removed on the paper. Rinse and repeat. When that didn't help either I hit the keys harder. Finally opened it up and found the little pins for those keys had broken free of their solder. No issues since resoldering them.

 

Probably my frustrated banging on them made sure they broke free. They can fail that way for other reasons too and sometimes were never good from the factory. And not just TI, normally their QC caught things like that. Over the years I've traced many faults on all sorts of electronics to poor or even skipped solder joints on circuit boards.

 

The above means the ability to solder is a good trick to have in your bag. I can put together a quick tutorial on it using a spare keyboard as the victim, er, patient and snap a pic or two. I'd bet there's plenty of hits on that topic in a web search as well. Maybe someone can point to a handy TI disassembly page to help on that front. The bottom comes off with the removal of some Phillips crosspoint screws, that should be all the farther you need to go since the keyboard bottom is right there in front of you.

 

How nice of TI to label all the key locations to make it easy! Each key will have a pair or pins protruding through the circuit board. You'll be looking for fine cracks or even movement of the pins as you press/wiggle the offending keys. May as well inspect all of 'em while you're in there looking around. While there can be cracks in the traces covered with a green coating, you're mainly interested in the grey/silver solder joints surrounding each pin.

 

Here's a pic of a $5 TI keyboard I bought surplus after the price war disaster that led to TI's exit. Lots of hacking and soldering going on! I converted the key matrix to use it on my fancy $50 Timex TS1000 I bought used back in '84. I really liked that TI99 keyboard, especially after trying to use the insipid flat membrane excuse of a keyboard that Timex/Sinclair favored (cheap). Maybe that played a hand in my upgrading to a real TI a couple years later, making it my main computer for the next 15 years and never got rid of it even after going Mac.

-Ed

 

TI kbd to Timex.jpg

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2 hours ago, newTIboyRob said:

before I even start to do anything, it just feels like the space bar isn't making any contact at all with the circuitry inside underneath.

If the key switch is physically broken, then no, trying to clean it or anything else will not help.  The key caps usually pull off, you just need to get under them and try to pull evenly on both sides.  Once you can see under the key cap, you can start to determine if the switch is broken or what might be wrong.

 

2 hours ago, newTIboyRob said:

and maybe I have to just be brave open it up?

Be careful if you take the 99/4A apart, it is *very easy* to completely tear the keyboard ribbon cable right off the keyboard.  I'm sure there are some guides or videos out there on taking apart a 99/4A, you might want to do some checking.

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