Re: IIgs won't start up -- ZipGS dead?

["PZ" <skierpaul@yahoo.com>]

> This is a 15/64 configuration ZipGS, which I've been running lately
> at 12.5 MHz. I hope I can get it going again, I find the machine
> unbareable any slower.

My first question is, was this ZipGS a custom high speed zip directly
from Zip Technologies? They supposedly sold some 14mhz units with a few
with additional IC's soldered upside down onto the card, I have never
seend one in person.  These are extremely rare due to the price that
they were selling them for.

The first thing to check is the XTAL, I've had a few go bad from
mishandling.  The 'can' type can get inserted backwards easily, once
thats done, they're done.  Find a 40mhz one just for stability testing,
then go up from there.

You'll probably end swapping out everything.  RAM, Xtal, cable, even
the CPU and 74xx IC's on the board.  Whats on the board now 74HCT's?

If the board still doesn't work, you'll know its either the ASIC or a
capacitor derived issue.

I'm assuming that you're using skinny cache ram, if you don't have
spares, you'll want to find an old Socket 4,5,7 motherboard with some
15 ns rams on them.

The ribbon cable/connector is a standard straight through type, not the
wierd crossover type the TWGS uses, so they're easy to make.

- Paul