From Newsgroup: comp.sys.apple2

Bill Garber <willy46pa@comcast.net> wrote in message 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.

Thanks,

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

If I remember correctly (and that's a *big* if), the drives are supposed to start the spin-up cycle as soon as power is applied, whether or not the motherboard starts talking. The 'grunt' from the drive sounds like one of
the voltage lines from the power supply is no good.

That could either be due to a bad power supply or a short on the board. I would suggest:
1) bench the power supply and check the voltage of each power line while driving a test load
2) remove any peripheral cards in case one is misaligned
3) also disconnect any 'unnecessary' peripherals in case, for example,
somebody mis-indexed a pin when the drives were plugged

and if that doesn't turn anything up:
4) try a different power supply.

The most likely failure modes:
#1: 90% - something is misaligned such as a Disk II cable connection or a socketed chip
#2: 9% - bad power supply
#3: 1% - failure of one of the unsocketed chips (expressly assuming that
all socketed chips are 100%)

Problem #3 is far more likely to occur in combination with #1 than by
itself.

Post-infancy chip failure usually does not occur unless induced by an electrical short circuit. I've seen #3 occur only twice, once when somebody was hot-plugging peripheral cards on the bus and once when a defective peripheral cable shorted the power supply.

Just my $0.02.

- Mike


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From Newsgroup: comp.sys.apple2

If I remember correctly (and that's a *big* if), the drives are supposed

to

start the spin-up cycle as soon as power is applied, whether or not the motherboard starts talking. The 'grunt' from the drive sounds like one of the voltage lines from the power supply is no good.

Hoped everyone would realize power supply has already been ruled out.

That could either be due to a bad power supply or a short on the board. I would suggest:
1) bench the power supply and check the voltage of each power line while driving a test load
2) remove any peripheral cards in case one is misaligned
3) also disconnect any 'unnecessary' peripherals in case, for example, somebody mis-indexed a pin when the drives were plugged
and if that doesn't turn anything up:
4) try a different power supply.

Running a bare board with drive on smart port, no cards, power supply
is known good. Short on the board is suspected, hoped someone would
have an idea which area on the board to zero in on.

The most likely failure modes:
#1: 90% - something is misaligned such as a Disk II cable connection or a socketed chip
#2: 9% - bad power supply
#3: 1% - failure of one of the unsocketed chips (expressly assuming that
all socketed chips are 100%)

Problem #3 is far more likely to occur in combination with #1 than by
itself.

Yes, I assume the same is most likely. Anyone with an idea which
area to pinpoint would help tremendously. Of course at $5-$20 for
a IIgs CPU with PS, it may be time to just dump this one and get a
replacement. I like to mess with them though.

Post-infancy chip failure usually does not occur unless induced by an electrical short circuit. I've seen #3 occur only twice, once when

somebody

was hot-plugging peripheral cards on the bus and once when a defective peripheral cable shorted the power supply.

I agree, there definitely was some careless activity going on here, not by
me, this GS came to me this way. ;-)
Thanks.

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



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From Newsgroup: comp.sys.apple2



"Jason Whorton" <jason at microxl.com> wrote in message news:vgnl2m6inncfc2@corp.supernews.com...

Will it boot without the floppy drive connected? I see you have a "known good" power supply. Are you using a "known good" floppy drive? Have you tried to flex the motherboard a little while it was on?

Actually, flexing the board while powering up, yes, and it
shows no differences. This thing will not do anything past
what I described in the first post. I also have some IIe and IIc
boards that pop up the logo screen and then display lots of
weird characters on the screen. I assume that since none of
these get past that point that there is probably a leading ram
chip gone bad. Sorry about this part, but my PC did this also
the time the first simm went. I believe I will have to remove
each ram chip one by one until I know for sure what is going
on. I can probably just grab a couple rom1 boards from eBay
but this is a Woz machine and I'd like it to stay original. Well,
I guess it's not worth the hassle, huh?

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



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From Newsgroup: comp.sys.apple2

Bill Garber <willy46pa@comcast.net> wrote in message 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



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From Newsgroup: comp.sys.apple2

Michael Pender <mpender@hotmail.com> wrote in message news:W%TOa.21193$C43.10105@nwrddc04.gnilink.net...

...snip...

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.

Come to think of it, it could also be a bad resistor or capacitor in the power-on pullup circuit -- but that's not likely to fail, even with abuse.

- Mike


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From Newsgroup: comp.sys.apple2

"Ed Eastman" <noone@nowhere.net> wrote in message news:3F0C7AEF.3020002@nowhere.net...

OK, this sounds like the CPU is not functioning. LAst time I saw this problem was when someone yanked the accelerator out and forgot to put a
CPU in.

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


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From Newsgroup: comp.sys.apple2



"Mark Cummings" <NOTfigjams@primus.com.au> wrote in message news:3f1028e3_1@news.iprimus.com.au...

"Ed Eastman" <noone@nowhere.net> wrote in message 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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