99er Forums

Someone knowledgeable in the field, can help me?
I bought a Texas TI-99/4A, excellent condition outside, but when I turn on the tv in the main menu where it says "press any key", nothing happens, I click on all the keys and nothing happens.
Is it a common fault on this computer? How can I solve?
I would appreciate help from those who know how to repair.

A lot of answers are possible here. Do you have the version with the grey keys or the black ones? The grey key types show up on eBay very often at reasonable prices (bare keyboards), allowing you to replace a bad one (of either grey or black type) easily. Black ones came in several versions, but most of them get gunky after sitting a long time. Try hitting a single key a few dozen times in a row--if it starts to work, you may have to remove the keytops and try to clean the contacts. A similar, related problem is multiple characters from a single key press--same problem, different symptom.

I hope this helps.

Ksarul Dear friend, thank you for your willingness to help me.
The keyboard version I own is black, and I'll try to do what I said, pressing a key several times, results can be q.
What I wonder is if you know the main cause of the failure of these keyboards, it is because of some faulty electronic component related to the keyboard or simply because the membrane keyboard.
Thank you.

Most likely oxidation, happens to all keyboards eventually, especially when they aren't used. The black ones are easier to fix, most of the black keyboards can have the key tops removed for easy access. I have had one or two that were sealed.

The beige keyboards are much harder to access, and more likely to fail in my experience.
Another problem I've seen is where the ribbon cable would pull away from the keyboard. More likely on the black keyboards - the beige ones were better designed.

Ben

My friend Ben, thank you for your feedback.
Did you repaired the keyboard (black version) of your TI?
The repair is easy?
Do you know where can I get technical tips about this type of repair, with illustrations if possible?
Thank you for your help on this forum this site that I love it.

Finally found the problem, I detected a lack of small pieces of conductive metal in the membrane keyboard. Anyone know if they still do membrane keyboard (as is done for the zx spectrum) and where to buy?
Greetings

Check on eBay... there was an online store a while back that had some in stock, new in bag, but it went offline without notice...
If I come across any, I'll let you know. I had a few in storage, but whether they are good or not, I don't know...

Ben

Ok Ben, once again, I am very grateful to him. I hope to have news from you soon.
Greetings

I am thinking in fixing the contacts of the circuit of the membrane with a conductive ink pen (silver), guess should work, what do you think Ben?

nelson3031 wrote:I am thinking in fixing the contacts of the circuit of the membrane with a conductive ink pen (silver), guess should work, what do you think Ben?

I'd say you have nothing to lose... let us know how it goes...

Ben