Tatung Computer Forum

I thought I would start the hardware traumas off!

The keyboard worked fine on arrival and for a couple of days but today started acting up.

I realised when I went to type DIR and D did not work.

I went through all the keys and the following do not work:

S D F G H J

Z

Note that when pressing D the caps lock light toggles!

I have taken it apart since to evict a few dust bunnies and prod the back of the keyboard with a continuity tester.
As far as I can tell all the keys apart from Z have continuity when pressed.

Any suggestions as to where next?

Thanks!

Lardo

Servisol Super 10 might work wonders and a ton of keyboard tapping.

Servisol Super 10?

Tapping I can do!

Edit - just ordered a can.

On an Electron I had, I eased off keycap, and depressed the plunger and worked in a spray of super 10 that way, I didn't bother pulling all the switches to bits.

vanpeebles wrote: ↑Sat Oct 26, 2019 3:45 pm On an Electron I had, I eased off keycap, and depressed the plunger and worked in a spray of super 10 that way, I didn't bother pulling all the switches to bits.

Will give that a go when the spray arrives thanks.

Here is the keyboard:


Didn’t want to risk removing the space bar. They are often a bit complex...

Is it possible to pull the keyswitches apart on these, should it come to that?

You need to:

1) Desolder the switch
2) Pull apart the mechanism with a flat screwdriver. Be gentle!

This keyboard can be fixed 99% of the time...

Before removing keys can you please let me know if the A and F1 keys are similarly affected? It could be that there's a problem with the PSG chip, which is in charge of reading the keyboard. See the hardware manual, section 3.9. I've spent quite a bit of time there recently with biggoil. If A & F1 are similarly busted we can look at the connection to the AY. The keys are in a matrix and those keys are all on one matrix row, driven by output A6. This row's selector appears on pin 14 of connector M006.

Hi sir morris!

Thanks for looking into this. So far I have checked continuity at the back of the keyboard. All the keys except Z show continuity at the back when pressed in. If I put the probes on the back of F1 or A and press the key I get a nice buzzing sound. I just get the sound of silence on Z.

I am wondering at this stage if the problem is with the key switch itself?

Below is a photo of the back of the Z keys pins.

Did you work a load of super 10 into the switch?

vanpeebles wrote: ↑Tue Oct 29, 2019 7:24 am Did you work a load of super 10 into the switch?

Its on order. Should be with me mid week I hope.