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The "Not Quite Amiga but still computer related category" => Alternative Operating Systems => Topic started by: leofoe on February 19, 2008, 12:10:02 PM

Title: 128D RETURN key does not work
Post by: leofoe on February 19, 2008, 12:10:02 PM

Today I got a Commodore 128D computer. It works, but has one nasty problem: the RETURN keys do not work. I opended the case to reseat all chips to no avail. Opening the keyboard also did not expose any problems. Because both RETURN keys do not work I think the problem is not in the keyboard itself.
Hope someone can shed some light...

Title: Re: 128D RETURN key does not work
Post by: redrumloa on February 19, 2008, 12:59:28 PM

I have a 128D keyboard with the exact same problem, return key does not work. I have not investigated it much yet. I do have a few bookmarks at home, I will post them later this evening.

FWIW the keypad is not enabled by default in 64 mode. If you boot to 128 mode the return key on the keypad will probably work.

Title: Re: 128D RETURN key does not work
Post by: leofoe on February 20, 2008, 08:45:12 AM

Both Return keys do not work in any mode.

Title: Re: 128D RETURN key does not work
Post by: redrumloa on February 20, 2008, 12:58:59 PM

Quote

leofoe wrote:
Both Return keys do not work in any mode.

Well that sucks! HERE (http://personalpages.tds.net/~rcarlsen/cbm/keyboard.txt) is a start..

Title: Re: 128D RETURN key does not work
Post by: Louis Dias on February 20, 2008, 01:55:03 PM

Perhaps I shoud open up my 128D and reseat all the chips to see if I can get a display to come up...

Then I could properly sell it.

Title: Re: 128D RETURN key does not work
Post by: leofoe on February 20, 2008, 09:38:20 PM

Quote

redrumloa wrote:
Well that sucks! HERE (http://personalpages.tds.net/~rcarlsen/cbm/keyboard.txt) is a start..

Thanks. I came across that nice description also.
Because both keys do not work, I don't think the problem is in the keyboard. But I will dismantle it completely if there is a good change the problem is in there after all.

Title: Re: 128D RETURN key does not work
Post by: leofoe on February 21, 2008, 03:17:13 PM

What I discovered so far is that on the dismantled keyboard, there is a shortcut between the most left and most right wire. I think these are pins 1 and 25 on the Centronics connector.

EDIT: Sorry, it's pin 1 and 24 on the Centronics connector. The wires on the keyboard are brown and purple-white. Can anybody confirm that these wires should shortcut?

EDIT 2:
Keyboard schematic (http://cbm.ko2000.nu/schematics/computers/c128/manual/51.gif)

Title: Re: 128D RETURN key does not work
Post by: leofoe on February 23, 2008, 09:42:01 PM

I got the RETURN-key working by reseating VIC U21. ENTER-key still a no go.