Acer 15″ FP450 LCD Monitor Power Supply Problem
Good day Sir,
I need your help with acer fp450 power supply, when plugged the standby fixed 5v supply is fluctuating, at 3v-5v. When connected to the mainboard and after pressing the power swith the power indicator would go blinking continously. 3.3v and 5v supply are measured half of what they’re supposed to be, but the 12v supply is really good and audio is also good. I already replaced all electrolytic caps, k2645, mpsa44, are replaced, but still same. I can’t get the standby 5v fixed and steady at 5v. I’ve seen that you have posted pics of the board but I still attached mine.
I hope you already encountered this and hope you’ll be able to help me.
Many thanks for sharing.
For this type of power supply the output of 12v and 3.3v was controlled by MCU. That’s why you could see that there are two 4 pins voltage regulator instead of 3 pins normal voltage regulator. One is for the 12 v output and the other one is for 3.3 v output. The main thing that you need to check is the 5v (MCU need 5 v to work) supply. If the 5 volt fluatuate obviously the 3.3 v output from the voltage regulator also fluctuate. Trace the 5 volt line back to the source. It could be the filter cap or the output diode leaky. I don’t think the primary section have problem because you already get the 12 Volt output. Sometimes a bad MCU and corresponding components could cause 5 volt to be unstable. Hope this helps!