• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Variable laptop power supply

Not open for further replies.


Hi everyone

Kindly I need your help, I have a Compaq PA-1500-051 18.5v 4.9A that I need to use as a variable power supply, I can't find schematic for this
Particular model, but a close one Liteon PA-1500-05 19v 4.47A, I found that a 28.7K and 4.4K resistors form a voltage divider connected to Pin 2 of the (unknown 8 pin IC it might be TSM103) I tried changing the 28.7K resistor with 20K pot in series with a 10K resistor
strangely while I set the 20K Pot combined with 10K to the value of 28.7K the output goes up and down from as low as .75v to 3.7v no matter how I change
the value the output never change accordingly !
I soldered the 28.7K resistor back the output is 18.53v & drops down with no load, and then when I put a 21w 12v car bulb the output voltage is not stable
goes up and down from 11v to 13v

liteon_pa-1900_05_out_power_schematic.pdf_1.png Liteon PA-1500-05.jpg 20170829_190046.jpg
Not open for further replies.

Latest threads

EE World Online Articles