PS/2 Port Power

gstopp at gstopp at
Tue Jun 3 18:47:29 CEST 1997

Do ya mean the serial port on a PS/2 computer? Is that a DB-25, or a DE-9, 
or a minidin, or what? If it's a DB-25, and it's a serial port, then it 
should be a male (computers are considered DTE) and so should be Ready To 
Send (RTS) which could be tied high but is usually under CPU control, yet 
tied high signals on RS-232 should be +12, not +5... To quote one of 
Asimov's computers: insufficient data for meaningful answer.:)
Actually it is a violation of UL (I think it's UL...) to have any raw power 
supply sourced voltage on a pin that's available to the outside of the box 
on anything other than an AC outlet. So even if it is actual +5, it's 
probably sourced through a current-limiting resistor. Probably it cannot be 
harmed by anything - try loading it down with a resistor to ground (start 
with 100 ohms) and measure the drop. You should be able to determine the 
series resistance using ohm's law.  

- Gene

______________________________ Reply Separator _________________________________
Subject: PS/2 Port Power
Author:  Christopher_List at Sonymusic.Com at ccrelayout
Date:    6/2/97 6:17 PM

Howdy DIYers -
Pin 4 of yer average everyday PS/2 port is said to supply +5v.
Anyone know what kind of current you can expect to get out of this port?
Does it vary by machine - is there an industry standard minimum?
What are the chances of frying the port if I draw too much?

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