Re: IIgs MB repair info

["Bill Garber" <willy46pa@comcast.net>]

"Mark Cummings" <NOTfigjams@primus.com.au> wrote in message
3f1028e3_1@news.iprimus.com.au">news:3f1028e3_1@news.iprimus.com.au...
> "Ed Eastman" <noone@nowhere.net> wrote in message
> 3F0C7AEF.3020002@nowhere.net">news:3F0C7AEF.3020002@nowhere.net...
> he did say that ALL socketed chips tested OK, so they problem must lay
> elsewhere.
>
> I have fixed one ROM-3 which would not boot, no legible text on the
screen.
> when I hit ctrl-reset I did get some reaction but still garbage on the
> screen.
> the cause was just 1 bad DRAM chip in the 1MB RAM area. I think there are
> about 12 RAM chips on the ROM-3 boards altogether, and I got to #9 or #10
> before I found the culprit, which pixxed me off somewhat :( although I
> quickly changed my tune when I realised that I now had myself a ROM-3 :)
>
> BTW due to the difficulty of removing the chips, I only removed one at a
> time to minimise potential damage to the board. the smaller 4164 DRAMs
were
> tested in a socketed //e. I used the System Test (Ctrl-SA-Reset) sequence
to
> proove they worked. the larger 511000 DRAMS were tested in a socketed
GS-RAM
> expansion card in another GS. a test program was used to test the DRAMs.
>
> replacement DRAM was obtained from a old PC video card. those ISA slot
types
> that contain only 256K or 512K of RAM are good candidates for spares DRAMs
> for the GS.
>
> the thing that I find amusing, for both the GS and //e is that the built
in
> test routines that test RAM (among other things), are a complete waste of
> time/space becuase I have found that if the RAM is faulty the tests won't
> even run. I guess this could depend on how they go faulty, but for me 2
out
> of 2 failed DRAMs basically locked up the machines they were in.
>
> Mark

Thanks Mark. That is where I will look next. Got tied up with my II+
lately and set that aside. Also working on getting software to a friend,
and will return to the broken Rom3 when completed. Busted drams
are a PITA, but if you say that is where the problem most likely is then
I'm on it. I suspect slow ram though. I get a particular screen outlay and
is never different. Must be very early startup so I will try slow ram first.

Thank you for the insight,

Bill @ GarberStreet Enterprises };-)
Web Site - http://garberstreet.netfirms.com
Email - willy46pa@comcast.net



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