Dead Key Range

[who]

Hi,

Thanks to the information found here I now have my EII working for the most part.  I do have one remaining problem:  The top seven keys do not appear to work.  I tried swapping the"dead" range of rubber contacts with a working range, but it didn't solve the problem.  My guess is that the keybed PCB, ribbon cable or something else is busted.

I searched the forum, but didn't find any answers.  Has anyone had the same problem?

Thanks!

[who]

I found this on the Yahoo Emulator list:

"Another possible problem of non working keys, which has happened to a few things
I bought cheap & broken in the past is corroded tracks on the keyboard PCB..
It's hard to know without looking at the pcb, but once found is easy to repair.
(Solder thin wires to bridge the corroded tracks)
The symptom from this is often keys that are not working and they are all say 7
semitones apart etc."

Time to open the EII and take a look.

[monkeyman]

Try opening it up and pushing in the memory boards and the chips...
This may help...
Something sounds loose///

[who]

I replaced a bad chip on the memory board, made sure the board  was securely fastened, cleaned the key contacts, and everything appears to be working except the top seven keys.  I'm at a loss.

[dr.c]

This is typically a problem either on the keyboard flat cable, or as well a trace on the keyboard printed circuit, the keys are scanned by block of eight.
Try to trace wich track is faulty with the .pdf located at :

http://mapage.noos.fr/gourci/EmulatorII_KB_Schematics.pdf

Please let me know when you have downloaded it, so I can take it away

[who]

Thank you for the help.  I downloaded the file and will take a look at my EII.

[who]

I ordered parts to replace the ribbon cable and the female IDC connectors.  Hopefully that will fix it.

[who]

Well, no luck with the cable.  When I installed the new cable the exact same key range was dead.  per Dr. C's advise I'm now looking at the circuit board, but I don't see anything wrong.  Does someone with a better eye for this see a problem in the pictures below?