Re: Upgrading ... a IIGS-- power mods

[supertimer@aol.com (Supertimer)]

Rubywand <rubywand@swbell.net> wrote:

>Obsbedia2 writes ...
>
><Rubywand wrote>
>> > Is the ROM 3 a better machine? Yes, it is. On the other hand, once you add
>> > the motherboard Slot jumpers to improve +5V and +12V power distribution,
>> > the ROM 3's quieter bus advantage disappears. (In fact, ROM 3 users who
>> > pile in Slot cards should probably add the jumpers, too.)
>> 
>> News to me.  Please, tell me more about these Slot Jumpers.
>
>     The jumper mod consists, mainly, of #18 gauge wires run from the power
>connector to Slot 3 and from Slot 3 to Slot 7 for +5V and +12V. The idea is to
>reduce the resistance between the voltage sources and Slot cards in order to
>reduce voltage drops and noise. Noise spikes can produce errors and crash the
>system.
>
>     On a ROM-01, the jumpers are a nearly certain requirement if you use an
>accelerator and/or boards like a PC Transporter or Second Sight (not sure
about
>boards like the RamFAST and Apple HSS SCSI controllers).
>
>     The ROM 3 is supposed to have heavier power distribution traces (as
>evidenced by audibly less noise through a Stereo Card).  Even so, it is
difficult
>to believe that the same designers who continued to install wimpy lead power
>supplies got it right for the Slot bus. (About the only way to be sure is to
load
>the Slots with a few power-sucking boards and measure voltages at the boards
plus
>look at noise levels with a scope.)

Well, here's the deal.  I have a PC Transporter, an 8MB memory
card, a TransWarp GS (which uses considerably more power
compared to a ZipGS supposedly), a Second Sight SVGA card
and an Apple High Speed SCSI card all in the same IIGS.  A
ROM 3 unit.  Everything works fine.  I do not hear noise through
audio.

On my backup IIGS, a ROM 01 model, I have an SCSI card,
4MB of memory, and various other cards.  It also works fine.

The flagship IIGS is in a PC tower case with a PC power supply
(hundreds of watts compared to the stock 70 watt unit) so if
something IS happening to a user's system, it may be a good
idea to try a beefier power supply before soldering wires to the
motherboard.  If the new PS does the trick, like it does for
my system, then the wires are not needed.  If not, the user
could always go ahead with the wires.

The flagship system worked before the towerization, though.
With the stock 70 watt power supply.  I'm sure everything is
less stressed with the PC power supply now, though.  Less
heat.