[no subject]

    A full-sized oscillator socket was soldered in, as well as a socket
for the chip at U8 (which had a 74HCT00E plugged in) with the
other chip next to it left as is. A standard WDC 14 MHz CPU was
installed, with a tin oscillator which was tightly zip-tied down.

>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.

    Since it was locked in with a plastic zip tie, there is no chance of 
that. I cut it off the tie last night and tried a 40 and 60 MHz oscillator
with no change--though, I did notice something odd (more below).

    When I powered up with the oscillator removed, I noticed this:
If I just barely touch the bottom half of the empty socket, the yellow
LED on the ZipGS lights up. Pressing Control-Reset turns it off.
If I hold my finger down on the socket when powering up, the
yellow LED comes on. With different oscillators (maybe because
of longer pins?) sometimes it'll light up on its own and stays on;
momentarily blinking off during a Control-Reset.

    Is it possible there's a micro fracture crack in the pin solder joints
for the oscillator socket? I mean, is it normal for the yellow LED to
light on from just lightly touching the socket or oscillator?

    I'm now leaning towards the oscillator socket being at fault,
especially since I pressed on it _just_ before the ZipGS went
dead (I also pressed on the socketed chips and CPU cable).
I'm pretty sure, even when a GS refuses to start up and in a
"dead" state, both the yellow and red LED should light up, no?

>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.

    If it is the oscillator socket, then a simple resoldering is all that
would be needed. Unfortunately since I don't own a solder pen
and have _zero_ experience with one (I'm not about to practice
on my ZipGS heh) I'm no better off. :(

Mitchell Spector