View Full Version : Compaq portable II power supply

May 12th, 2016, 12:57 PM
Hello, I've just acquired a Compaq portable 2, but the power supply is dead one of the small riser boards on the supply has burnt out. I wanted to know if any one had a pin out for the power connector so i could try make a new PSU or a schematic for the power supply.

many thanks, josh.

May 12th, 2016, 08:08 PM
Can't you deduce the pinout from the original power supply ? Are there any markings on it ?
Photo perhaps ?

May 12th, 2016, 11:02 PM
I wish I could but there are no voltage marking on the power supply or the board. I've found a manual online but it doesn't cover the psu in depth. I will upload some pictures when I get home tonight

May 13th, 2016, 09:07 AM
There are several ways to find out which is which:
You will need a multimeter for this:

Have a look at the capacitors and trace or measure which pin goes to what capacitor, for example a capacitor rated for 10 Volts will probably connected to the 5 Volt circuit, a capacitor rated for 16V will probably be connected to +12V and so on. Ground connections should be easy to find. +5 Volts will go to most of the TTL chips (74LSxx)
Other useful measuring points are power cables connected to for example a floppy drive or harddrive, if the pinout is standard you will find +5 and probably +12 Volt and then you can try and trace back the connection to the power supply. Look for any RS232 driver chips like MC1488, those are connected to + and - 12 Volts so can be traced back too (pin14 is +12 Volts, pin 1 is -12 Volts, pin 7 is ground).

May 10th, 2017, 02:15 AM
The mother board will have the voltages pin out labeled on the mb base, also
Did you find the PSU schematic, I am also looking for schematics for my Compaq portable original especially the PSU and vdu card. Thanks