Re: transwarp weirdness

[Rubywand <rubywand@swbell.net>]

Ben Zotto writes ...
> 
> Hi all,
> I have a IIGS setup with a Transwarp GS (rom 1.5, stock cache)
> plugged into slot 3.  I get mostly great, troublefree performance
> from the system, but every few days, the system will go funky on
> me, producing the following types of symptoms:
> 
> - hanging while booting system 6.0.1
> - crashing to the monitor during booting
> - displaying unnecessary screens about appleshare fsts, drivers etc
>         during bootup.
> - ...and then crashing to the monitor.
> 
> These things all happen arbitrarily and with no rhyme or reason.
> Then, after some futzing and sweettalking, the iigs will be completely
> normal again.   This is NOT caused by RAM, the SCSI card or hard drive,
> the power supply (i've tried 3), any particular disk (although prodos 8
> software always seems fine; it's gs/os or p16 stuff that gets weird),
> heating/uptime effects, or system speed.  It's totally random, and
> eventually it just starts working fine again with no harm done.
> 
> The system self test passes,the TWGS selftests pass, and Claris' memory
> exerciser passes.  (Occasionally during a funk, the system diagnostic will
> fail on something random, like the 1/4s interrupt (?) or something).
> 
> I figure this must be caused by the Transwarp somehow (symptoms did not
> occur before I installed it), but it's entirely non-consistent.
> 
> Anyone have any hints or thoughts before I try to find/swap in a different
> motherboard? (About the only variable I haven't switched yet)....
> 
 ....

     If your GS is a ROM-01, the motherboard could be a problem. Quite a few
early GS's came with a defective ADB chip-- think it's the ADB GLU IC; but, it
may be the ADB Controller. The chip works most of the time but starts to
glitch over a narrow temperature range. The one on our first GS motherboard
would bomb at low room temperatures. (Naturally, the IC is soldered onto the
board. So, unless you can find a good IC and are willing to do some tricky
desoldering and soldering, you need to replace the whole board.)

     The fact that you did not get bombs before adding the Transwarp could be
a coincidence-- like you added the Transwarp about the time you started
running your air conditioner. Or, the presence of the Transwarp has pulled
down voltage at the motherboard and moved a borderline ADB IC into an
operating range where it glitches.

     An IC that screws up at _low_ temps is, from time to time, going to crash
your system upon startup-- i.e. if the room temp is right. If you get past
startup, there's a decent chance that normal heating will move the IC into a
range where glitching ceases. (I remember that, at first, we figured
over-heating was the culprit and added a SystemSaver-GS-- crashes
_increased_!)

     A fairly good check is to get your system going (i.e. it doesn't crash
upon startup) and try accessing the CDA menu (OpenApple-Control-Escape).
That's a reasonably ADB-intensive operation which will often crash a GS with a
glitchy ADB chip.

     Continuing the check ... turn Off the computer and spritz the ADB GLU
chip with circuit coolant. Turn On the computer and see if it crashes.

     A pretty good fix was to place a small 12V bulb on top of the IC and
surround it with bits of duct tape to make a mini-oven. The bulb can be
powered by the 12V pins near the rear of the motherboard.


     Another possibility is that you have a fairly loaded system-- just the
Transwarp is a pretty good start-- and your power supply leads are too skimpy.
Swapping in other power supplies will make no difference as long as the
substitutes have the same kind of pissant leads.

     Aside from the additional load represented by a Transwarp and the
increased noise developed across the PS leads, you have the fact that, for
circuits running at higher speeds, noise spikes become more noticeable. (A
spike that would be ignored at long 'bit times' can more easily change a bit
value at short bit times.)

     There's some information about swapping in better power supply leads at 
http://206.14.25.120/~cturley/a2zine/gswv/IdidThePSmod.html  .


     You mentioned Appleshare. Ripping out anything related to Appleshare may
fix your problems.



Rubywand