Re: IIgs MB repair info

["Michael Pender" <mpender@hotmail.com>]

Bill Garber <willy46pa@comcast.net> wrote in message
bpadnXU6LuAYw5eiXTWJiQ@comcast.com">news:bpadnXU6LuAYw5eiXTWJiQ@comcast.com...
>
> I have a IIgs MB I am in process of trouble-shooting.
> Any FAQs, docs, or other info deemed worthy of use
> will be greatly appreciated. Now, to avoid responses
> concerning already tried procedures, all the socketed
> ICs "do" work. There is no start, I repeat, will not pass
> video pretest. I have an 800k drive attached. There is a
> small grunt from the drive with no led activity, and
> display shows black screen with lower half white and
> 6-7 pixilated rectangles up the left half of the black,
> and black ones down the right side of the white area.
> If anyone knows what is causing this, please inform.
> If I hear from several sources that the board is dead,
> I will proceed to remove all component parts that I
> can and scrap it.

Before I say this, I admit the solution is a little weird.  But what about
putting the motherboard in the freezer until it gets nice and chilly, then
powering the board and monitoring which chip or chips get hot first?

There should be a visible difference between the heat output of the
dead/shorted chip and the heat output of all other chips on the board.

It could be one chip gone bad or it could be multiple chips -- but it could
also be a short in the PCB.  If its a bad chip -- which is consistent with
abuse -- then this might work.

If the "refrigerator" solution is too radical you could either spray each
chip one-at-a-time with 'freeze' spray or use an IR-sensitive camera to
image the board during startup.

- Mike