Apple //c startup trouble

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Joined: Oct 8 2004
Posts: 6

I have a z80 card in my //c. I found that CP/M programs didn't work anymore, but usual //c programs do. So I opened it up and checked the z80 card that carries the 65c02 too. It turned out that the z80 card cable that should be connected to pin 2 of the TMG chip on the //c mainboard was not connected anymore. I clipped it to pin 2 again and closed the //c. Since then I get a high frequency non stopping sound when I switch the power button on and nothing happens. Did I kill my //c or can I fix it? Any hints?
Here's a photo of the card connected to the mainboard and to pin2:

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Offline
Joined: Oct 8 2004
Posts: 6
When I remove the internal di

When I remove the internal disk drive the sound is gone. When I connect the drive again, the sound is there again and it still won't start.

Offline
Joined: Oct 8 2004
Posts: 6
Ok, I put the disk cable on b

Ok, I put the disk cable on both sides several times in and out and now the //c boots from the Apple 1 disk again. But it still ignores it's old CP/M 2.23 disks.

Offline
Joined: Oct 8 2004
Posts: 6
Now I found it: The cable mus

Now I found it: The cable must be connected slightly different. I had turn turn the connecting clip 90 degrees clockwise and now CP/M 2.23 is booting again. Man this rocks. 20 years old and still working, even the disks.

woogie's picture
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Joined: Dec 20 2003
Posts: 267
Cable Connections

While you're in there, CAREFULLY check all of
your other cable connections to make sure none
of them have worked loose over the years. This
is normal for computer gear due to handling,
temperature changes due to heat build-up and
oxidation of connections. If in doubt, CAREFULLY
remove-and-reconnect a few times (be sure to
observe connector polarity) to clean up the
connections of any oxidation and to assure a
known tight, good connection.

You might also want to check the proper seating
of any socketed IC chips. (Same procedure as
above)

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Pease's picture
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Joined: Feb 11 2004
Posts: 30
You're lucky

Hey MacMark.......
You're lucky that you didn't fry something when you hooked the stuff up backwards. You have to be really careful
about the position and the polarity of those connectors and pins. Glad your computer is back in working order.

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I love old Apples!

walt's picture
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Joined: Nov 11 2004
Posts: 9
Did you mess up any of your d

Did you mess up any of your disks when you tried to boot up and the drive was hooked up wrong? Sometimes it will screw up the boot sectors and the disk will get ruined.

Offline
Joined: Oct 8 2004
Posts: 6
Disks are ok

The disks are all ok. The //c didn't use his drives (intern, extern) when the Z80 card was connected in the wrong way.