| Attachment | Size |
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 IIGSrom03.JPG | 84.69 KB |
No luck today while testing a bunch of boards ..
IIGS Rom03
Formerly the board had problems to start from Disk, then it wont boot at all and now after one month ago i tried again and now it´s dead.
Anonymous
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Try re-seating all of the socketed chips. I have a RamWorks III card that showed a bad memory chip when tested. I re-seated it and all is good. If that doesn't work, take a voltmeter and check the voltages on the power supply. If these aren't right, it can cause all sorts of weird problems. Someone on here should be able to help if this don't work. Tons of knowledgable people on here. Hope you get it without too much trouble. Good luck.
There are only 3 socketed chips: µP and the two ROMs.
PS is ok ...
Hello Andre,
viewing the picture causes shock..... in early days when IIGS boards have been made, the bondings of the large chips wasn´t that good to be stressed that hard ! The very minimum rule is that the board MUST ENTIRELY be placed on solid base ! If board has hangover nearly 35% of the boardsize beyond the table like in this picture - this stresses the board and the bondings of the large VLSI logic chips ( all 3 ) close to the powerunit. This correlates with your desctiption, that the trouble started with the access to the diskport.... normaly next stage would be loss of the access to the slots... and finally total kickoff with no boot....
1. attempt: place the board correct to solid plain place with good isolation below... wood does not lead curreent very well - but it surely does not completely isolate..... then reseat carefully all chips in the sockets ...
if you are realy lucky - only one or two chips have untightened contact from socket and the board jumps back to life... if not some of the bondings of the VLSI chips have been damaged by stress and now have microsplits / tearoffs....
in that case normaly i charge the board to be dead.... but some guys have resurected boards with similar problems in the oven... i´ve never done that, but there is some info out there in several forums about the problem ...
search for topics related with the MAC Book Graphic power chips... it might be a solution that works, although i have never tried that by myself....
if you don´t find a solution - you should at least harvest the chips from the sockets...there might be a good chance that they are not dead and can serve as spareparts for other boards with chipdamage....
sincerely speedyG
The board was faulty even first in the IIGS case and i removed it to inspect the lower side of the board.
During this picture there where rubber feets under the board.
I dont think that the self-tension of a very light weigh mainboard is so hight.
Its much more stressable for the board to remove oder insert it back or fromn the case.
I also inspected (and measured)all of the bondings with no negative result.
if microfraction occured you probably measure wrong results....
pressing down the tip of the measurement pencil may close the break
and when lifting up the crack may open again.....
and if you say that "tension occured while extracting the board"... how do you extract ?
did you not press the upper part of the locks of the distance clamps together to unlock - while gently lifting the board without power ?
No, i meant that a leighweight board like this will not bent from itself even when its 1/4 in the air.
Removing was easy but i think every handling on PCBs is some stress for them.
I have a SMD hot-air station and some careful rework gave no results.
Hello AndreLev,
then there is only very small left that you can try....
did you check that the ROM´s have not been changed in position by mistake....
the picture on the monitor indicates that the CPU crashes within the very first 100 cycles....
otherwise if there would be access to the RAM you would view changing blockgraphics instead of solid vertical lines with no change.....
by that indication the trouble is at the datalines there is no traffic or even the CPU does not perform steps of
instructions ( no cycle signals from generator ).... in general that is caused by faulty "Mega2" chip....
( thats the largerest square VLSI chip close to powersupply edge ) and there is nearly no chance to change that chip...
do you have an oscilloscope to view the signals at the CPU ?
sincerely speedyG
In the last 20 years I've had that same screen show up twice. Once in a ROM 3 and it was a bad 65816. The other was in a ROM 01 and it was bad RAM. I'd swapped out all the socketed parts and since I had a lot of suitable RAM I tried that. No diagnosing, I just lucked out. Your problem may be something different entirely.