Re: Dead IIgs motherboard, fix?

[sicklittlemonkey <nick.westgate@gmail.com>]

On Aug 13, 2:38 pm, oz390gta <oz390...@gmail.com> wrote:
> I have few dead IIgs motherboads, one of which I would like to
> resurrect. When I turn on the machine the 5.25 drive light comes on,
> the green power light LED on the motherbroad comes on but all I get on
> the screen is white squares. I have seen this screen pattern a few
> times on various dead IIgs's. Does this give any clues to what is
> wrong? I have removed all chips that are removable and made sure all
> are seated properly etc. I have check for dead capacitors also,
> nothing is visually wrong or out of place.
>
> where do I start?
>
> oz390gta

Hopefully someone with more GS hwardware debugging experience will
chime in shortly ... and they will want to know what revision GS you
are trying to revive. Do you have a working MB to swap parts in from?

Generally in debugging old boards a good place to start is using a
logic probe to check for clock pulses to the CPU. If you have pulses
or don't have a logic probe (no excuse really, they're cheap) you
could swap in a known working CPU.

You should also check the power supply voltages to the MB are ok, but
it sounds like you're getting video so should be ok I'm guessing.

Cheers,
Nick.