Re: ATTENTION HARDWARE GURUS (was Re: Freakin' Second Sight Board)

[rubywand@aol.com (RUBYWAND)]

In article <Pine.SOL.3.91.960107110843.11982A-100000@moose>, Paul Schultz
<pschultz@med.wayne.edu> writes:

>Subject:	ATTENTION HARDWARE GURUS (was Re: Freakin' Second Sight
Board)
>From:	Paul Schultz <pschultz@med.wayne.edu>
>Date:	Sun, 7 Jan 1996 11:26:17 -0500
>
>Well, I thought all was well after I changed my power supply's
>+5, +12, and GND leads to 16 guage stranded wire. It did seem
>to reduce the "line noise" and allow me to use my SecondSight
>card.
>
>But, after 30 - 60 minutes my computer crashes. 

    Too bad. Maybe some hardware gurus will drop by later on. When they do
they may want to know ...

1.  Which cards are in which slots?

2. Do you notice that any components on a peripheral board are getting
especially hot?

3. What sort of cooling system do you use? (Like, is a System Saver/gs
sitting on top of your IIgs drawing in air?)

4. What kind of power supply is installed? Is there a some kind of switch
to go from 'normal' to 'hi' output? If there is, what is the current
setting? If there is a lower setting, what happens when you switch to the
lower setting?

5. When you turn ON the computer, what is the voltage on the +5V line at
or near the power supply circuit board? Does this voltage change over a
period of 20-30 minutes? (You can sample this using staight pins to pierce
the insulation of the +5V lead and GND lead where they come out of the
power supply.)

   
>
> .... Apparently, my +5V line now drifts slowly higher after powering
>up. This occurs at the motherboard plug so it doesn't look like
>a problem within the motherboard circuitry.
>
>EXAMPLE: On powering up, my +5V line reads 5.01V at slot 4. It
>slowly creaps up to 5.22V over about 30 minutes at which point
>my IIgs crashes.
>
    Your meter may be responding to line noise. Slot 4 is a long way,
resistance-wise, from the motherboard plug. 

    It may be time to just 'bite the bullet', pull the motherboard, and
add #18 +5, GND, and +12 leads from the power plug points to corresponding
points on Slots 4 and 7.   

>
>After powering down my IIgs power supply, I noticed that I still
>had about 0.18V reading on my +5V line!! It turned out my VGA
>monitor (hooked up to my SecondSight) which was still powered up
>was causing it!! 
>

    Voltages from all sorts of circuits (RGB outputs, etc.)  can wend
their ways back to the +5V line. This does not sound like a problem.