Re: Apple IIgs power leads (was: Re: 911 Fatal Error on TransWarp GS?)

[Rubywand <rubywand@swbell.net>]

     We have a spare IIgs (from relatives who didn't use it much); so, I pulled
the power supply to do some tests.

     The spare IIgs is a little later model. Although the power supply is the
original complete with the original leads, it comes in a brushed aluminum box
(instead of the steel one used for earlier versions).  Otherwise, it seems to
be the virtually the same. (The connector is slightly different.)

     Direct measurement of the voltage drop across the +5V lead at 3 Amps gave
just 0.025V. Figuring a corresponding drop (about 0.013V) across the two Ground
leads results in a total drop of roughly 0.04V. (For 4 Amps, the total was
about 0.06V.)

     This pretty well supports your assertion that there is no way the drop
through the leads at 3 Amps could be anything like 0.3V. Instead, it must come
from an error in regulation. Heavier leads do, mostly, eliminate the drop.

     By the way, this particular power supply was very solid (at 4.9V) up to
beyond 4 Amps. Since much of the noise in a system is in the RF range, it's not
clear that solid DC performance equates to significantly lower noise across the
PS and its leads.

     It happened that, during the heavy loading, a capacitor blew-- POP!!! with
billows of sweet smelling smoke. Turned out to be one of the .22uF 200V caps
used in the input filtering; so, the blow-out probably was going to happen
whatever the load. (Replaced both caps with new .22uF 400V caps.)

     Anyway, I've revised the FAQs. Thanks for your help!



Rubywand