Re: Apple IIgs Crashed

[Rubywand <rubywand@swbell.net>]

Bryan Parkoff writes ...
> 
 ....
>     My power supply is Vulcan.  It has two 2 GB hard drives inside Vulcan
> power supply with Turbo IDE card which it was modified by myself.  I believe
> that two hard drives may have stolen too much power which it causes not to
> give enough power to the Apple IIgs' motherboard.
>     I have found naked 3" X 5" power supply board from any electronic store
> which it has same +/-5V and +/-12V.  It can replace the half defective power
> supply board inside Vulcan unit.


     One check is to turn ON your computer, let it sit a minute or so, and
measure the +5V voltage on the motherboard. 

     You can clip the black (gnd/-) meter lead to some Gnd place and sample +5V
with the red (+) meter lead at a +5V point on the motherboard-- like pin 16 of
some 16-pin 74xxx IC, etc.. Try to check at two or three different points on
the motherboard.

     If the Voltage is less than 4.75V you very likely have a PS problem.

     You can check the +12V output at the Fan connector near the back middle of
the motherboard. If it's low that would be another indicator of a PS problem.

     
>     I can't be certain how much maximum AMPs are required to sustain enough
> power.

     Here is info on the standard IIgs PS and PS connector ...

  7    - 5 Volts              0.25 Amps 
  6    -12 Volts              0.25 Amps 
  5    +12 Volts              1.0  Amps 
  4    + 5 Volts              4.0  Amps 
  3   --nc-- 
  2    GND 
 *1    GND 

* When you are sitting in front of the computer, pin 1 is nearest you.
  
     It turns out the the standard IIgs PS with the original leads cannot be
counted on for much more that 2.5 Amps on the +5V output, at least not for very
long. Loading down the standard unmodified PS with an accelerator, SCSI
interface, extra RAM, IDE interface, internal hard disks, ... eventually leads
to PS failure.

     I do not know what the Vulcan PS specs are. Probably it offers 1.5A or
better on the +12V output in order to run the Vulcan drives plus take care of
IIgs requirements.

     If you replace the Vulcan PS, go for 5-8 Amps on the +5V output and 1.5-2
Amps on the +12V output. Most likely the main problem will be finding a
4-voltage PS that will fit in the Vulcan case while also meeting cooling
requirements. Most replacement PS's will probably do fine with the airflow
supplied by a SystemSaver IIgs.


>     If it does not resolve the problem, I would have to use standard power
> supply and put two hard drives externally to the Turbo IDE card.  I may be
> required to replace thin wire to thick wire inside standard power supply.
 ....

     It may be a lot less bother to move the Vulcan outside and install a
replacement PS in the IIgs. The PS in the Vulcan may work okay for just running
the Vulcan.


Rubywand