I figured out a way around the battery voltage sensing.
By the way, there seems to be more than one model of this PSU in the market. For models with just 2 pin output and no battery voltage sensing you can ignore this advice, you should be getting aprox. 19V DC output at all times without issue .
If, like me, you have the three pin version and want to use this PSU for something other than an ACER laptop you can try this. WARNING! Do it at your ouwn risk and only if you understand what you are doing.
There are two optocouplers on board that feed back information from the low voltage (19V DC) to the high voltage (mains 230V AC rectified to 380V DC) side of the transformer while maintaining isolation between them:
1- on the top side (transformer mount side) there is the one that feeds back the info on secondary voltage to the controlling IC, leave this one alone as you need it for regulation of the voltage output.
2- on the copper pads side there is a second optocoupler labeled IC33 between two black adhesive rubber spacers (see photo by HAN in one of the posts before), this is the one that tells the controlling IC to power OFF the output when there is no voltage level feedback from a battery, if you short the two pins of the optocoupler ON THE HIGH VOLTAGE SIDE you will disable this function.
After you disabled optocoupler #2 you should get around 1V DC output, you can feed this directly to the sense pin and the PSU will output the full 19V DC. It seems there is some circuitry on the output side also requiring a battery voltage sense feedback to operate.
Disclaimer and warnings:
- This process may disable also some other performances (i.e. output overcurrent/overvoltage protection). I have not taken the time to reverse engineer the circuit well enough to know this; I am willing to take the risk for me but I will not accept any responsability for what others do with this info.
- The big 400V capacitor on the high voltage side remains charged for a long time and can zap you badly if handled without care, even if the unit is not plugged. It hurts!
- If you do not understand my explanation above you should NOT be attempting any of this.