Apple II Plus - Keyboard not working

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Joined: Jun 18 2015
Posts: 135

I'm trying to test an Apple II Plus. I loaded the DOS 3.3 master disk. But, I press every key on the keyboard and I can't get any characters to show up on the screen. Is there something that I'm missing? Thanks for any help you guys can provide me.

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speedyG's picture
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Joined: Nov 16 2011
Posts: 2413
Re: Apple II Plus - Keyboard not working

Hello Apple7159,

welcome at the community,

there may be several kinds of problems present......

first you should examine if the cable between keyboard and mainboard is installed correct
( also checking orientation of the pin 1 at the plug at both sides of the cable ! )

and checkout if the seating of the chips in the first 2 rows of the mainboard
is correct.

There are several former threads here in the board related to this kind of problem.
you will get them by using the search function at the top right side of the page.

sincerely speedyG

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Joined: Jun 18 2015
Posts: 135
Re: Apple II Plus - Keyboard not working

Hey thanks for your suggestions. I tried another keyboard on the computer and it worked fine. So, I'm assuming there is something wrong with my keyboard. Do you think swapping in another keyboard encoder would fix the problem?

speedyG's picture
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Joined: Nov 16 2011
Posts: 2413
Re: Apple II Plus - Keyboard not working

Hello Apple7159,

first of all that depends to the kind of keyboard inside.
A picture here of the keyboard ( and if it´s 2 parts then
pics from both parts ) would be usefull for diagnosis...

In general cases the encoder chips only has been destroyed rare...
rather more common diodes or parts of the logic chips get destroyed much faster
and keep harm away from the encoderchip.

Most common reason for such damages have been wrong inserted plugs...
this causes the powerlines to become connected to lines they should not touch
and produce a shortcut at the keyboard PCB close to the cableplug area.

sincerely speedyG

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In early days I had a lot of money but no time - now I have no money but a lot of time....
the second part includes less friends but a lot more joy on life....

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Joined: Jun 18 2015
Posts: 135
Re: Apple II Plus - Keyboard not working

Speedy, thanks for your reply. I switched the encoder board from my working keyboard into my non working one. The keyboard works now. I looked at the non working one, there was an extra wire, were some connections were jumped. There were also some arrows drawn at different soldering points. I'm assuming it has been repaired in the past. Hopefully, someone has a spare encoder board that they can sell me.