Re: IBM Power Supply to IIe or IIgs : tech questions

[buggie@musca.unm.edu (stephen e buggie)]

Thanks for the advice.  I now have my flagship IIe connected to a 150 
watt IBM power supply and all is well.  No crashes, etc.

Could you expand on the final paragraph (below) about the minimum loads 
needed to prevent self-cooking of the PS?  With my huge interface cards, 
I expect that my IIe (and IIgs) are drawing ... may .... 60-80 watts.   
(The load is high enough that even the so-called AE heavy duty PS was 
doing overloads.)

But the idea of a MINIMUM LOAD would suggest that the 150 watt size IBM 
power supply is preferred over the 200 watt model --- is this correct?
Please explain.  

Have any other users of IBM power supplies experienced "underload" 
problems while using these power supplies with Apple IIs?


Steve Buggie	buggie@unm.edu


IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII




 : In many PC-style power supplies, each voltage is coming from only a single
: source inside the power supply.  Better supplies list the maximum supplied
: amperage for each voltage, as well as the overall wattage.  For example,
: with your 150W supply, the breakout might be 16 amps for the +5V section
: (80W), 4 amps for the +12V section (48W), 2 amps for the -5V section (10W),
: and 1 amp for the -12V section (12W).  Depending on the size of the supply
: wires, a single wire would probably be sufficient for all but the +5V section,
: which would require 2.


: On a good PC-style supply, the P8 and P9 connectors are not flimsy.  If yours are
: cheap, you would probably be better served by cutting them off and replacing
: them with the appropriate connector for your machine.  An easy and cheap way
: to get the male connectors would be to salvage them off an old unwanted
: IBM-type motherboard.  As I mentioned above, you would use more than one wire
: to "spread the load (amperage)", depending on the size of the supply wires.

: A word of warning:  Virtually all switching power supplies require a minimum load
: to keep them from slowly cooking themselves.  Better supplies list the minimum
: load requirements, and they also sense voltage/current conditions that are out of
: range and shut themselves down.  Cheaper supplies do not protect themselves.
: Just cooking the power supply is annoying... when the cooked supply takes your
: //gs motherboard with it, that would be *very annoying*.  Be careful.