Commodore 4032 Keyboard Fault.

[Pet Rescue]

Hi all I have just aquired a working 4032 fat 40 I think as it has a 12" screen and an assembly 8032080 board.

The cursor blinks but when any keys are pressed nothing happens, I have reseated the UB12 6520 and swapped it with the other 6520 on the board but it is still the same.

Could the 74ls145 bcd be at fault or am I barking up the wrong tree?

 

[Pet Rescue]

Well I've learned a very good lesson today don't assume anything (afterall it makes an ass of u & me). My 74LS145's arrived today so it was time to dig out the pet and the tools and get cracking. I removed the old 74LS145 and put a socket into the board and fitted the new IC. Switched it on and ....................

Nothing still no functioning keys. Well this pet must have given the previous owner a bit of a run around as he had re soldered the keyboard connector and some of the keyboard pcb screws had been interfered with. So it was time to delve into the keyboard which couldn't be at fault could it as no keys operated?

After stripping down the pcb and cleaning the contacts with an eraser they didn't look dirty but I gave it a go and after a quick try SUCCESS!!!!

It isn't always something complicated it is sometimes quite a simple solution.

But not one key operated and that is what threw me, if at least one had worked I may have found the fault quicker!

 

[tezza]

Yes, sometimes it's not the ICS. I had a similar problem with an Apple Lisa 2. However, in this case there was at least ONE key (and only one) which was responsive. A google around soon found that this kind of symptoms certainly was a keyboard contacts issue.

Yes, those PET keyboards can become non-responsive. Mine was bad. I tried the eraser and the graphite trick. It helped, but the keys still needed some force. Luckily I managed to source an unused keyboard from billdeg on this forum. He might still have some spares?

Tez

 

[Pet Rescue]

After I cleaned up the board with an eraser and a bit of alcohol I can't believe how responsive it is.
I don't need that much force either luckily unlike some of my other pets so it really has been a complete
turnaround from no response to quite a normal operation.

Having not one key work really threw me a curve ball!

Thanks for the heads up on billdeg I will keep it in mind.