Disabling Current/voltage protection of atx smps

Thread Starter


Joined May 2, 2020
Hi guys,
I have an smps which I need to power a car stereo. The smps is marked to supply 12v 15A which should be enough to power the stereo which need 12v 10A. I joined multiple yellow and black wires for output. But when I increase the volume little bit,the smps shuts down.i just connected a single speaker with low volume. Can anybody help me to disable the protection circuits of the smps.it has two ic's..AZ339p E1 and AZ7500BP..pls help..I am attaching data sheets and images .



Joined Jun 4, 2014
There is something that might help without risk. Connect a 10Ω 5W resistor to the 5V output. These supplies often do not like having no load on the 5V output.


Joined Jun 22, 2012
The Az500 is the same chip as TL494, pin 4 is the shutdown, it needs to be grounded to pin 7 for disable shutdown.

The LM339 is for over, under voltage, and shorting out of supplies to each other, which makes pin 7 High to shutdown the psu.

Before you do this, measure the current of your radio and see how much you can get before it shuts down. There maybe a fault on the current limit, wich is monitored using the pulse transformer Primary winding.