Re: Question(s) on AST RAMSTAK Plus & AE Vulcan Hard Drive

On Dec 9, 8:10 pm, "Michael J. Mahon" <mjma...@xxxxxxx> wrote:
capknight wrote:
Thanks for all the info on the drives. I've already tried out a few;

Seagate:
Model #: ST3120A - 105 megabyte

Quantum:
Model #: ProDrive ELS PI12A492 - 120 megabyte

No go on both of those drives.

The original drive in my Vulcan is a;

Western Digital:
Model #: WD93048-A - 40 megabyte

It almost seems that AE wanted it to be difficult to upgrade a
Vulcan by swapping drives--maybe because they had such a nice
profit margin based on drive capacity, and drives have always
been getting bigger and cheaper.  ;-)

When I connected the drive up to an external firewire chassis (for
power only)
it kicked in and was able to boot. The internal Vulcan power supply
only seems
happy enough to run the IIGS. I'll probably pull it out completely
when the
LittlePower Adapter IIGS from ReactiveMicro comes.

That suggests to me that the +12v supply is the one that has
limited capacity (though if the problem is on the "line side" of
the supply, then only the total load matters).

If you open the supply (as you have if you have access to the
disk drive ;-), you can examine the larger electrolytic capacitors
near the AC line end of the supply--they will be fairly high voltage,
like 250v, and medium-large capacitance, like 100uF.

These are the most likely capacitors to be causing your problem, since
as they dry out, they lose capacitance and increase their equivalent
series resistance, both of which make them less able to "hold up" the
supply voltage for the high frequency switch between AC half-cycles.

You don't need to remove the capacitors to "test" them.  Just bridge
the old cap with a new one of equal or higher ratings (both capacitance
and voltage), and if the supply works properly, then that cap needs
replacing.  (Watch polarity carefully, use clip leads or temporarily
soldered "flying leads" to avoid shocks, and discharge (short) the
capacitor after powering off before getting your hands across the
terminals.)

-michael

******** Note new website URL ********

NadaNet and AppleCrate II for Apple II parallel computing!
Home page:  http://home.comcast.net/~mjmahon/

"The wastebasket is our most important design
tool--and it's seriously underused."

Definitely they were interested in protecting a profit margin! Haha..

I'm curious to see how the "Gold" ROM works in the machine. I think
it's supposed
to come today from ReactiveMicro.

I'll check the power supply out when I get more time at the end of the
month. It'll
be fun to get the Vulcan behaving properly again. I always wanted one
when they
came out and it's fun to just play with it. I've heard it's not a
terribly fast system, but
it is very cool how they were able to wedge this thing into the IIGS.

I'll drop back when I get the Vulcan card upgraded and I find some
EEPROMs for
the AST Ramstak card.

Best!

C
.

Relevant Pages

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