Epox EP-4PEA9I rev. 2.2

As I said in header Mobo is not starting up even on force. When ATX Supply is on nothing is worming up even slightly.All components are cold. On PS_ON there is 0.8V and on Reeset 0.32V. On USB-s I measured shortcut to null on +5V but all data+&- aren`t in shortcut. On ATX connector it self there is no shortcuts to null, even on +5vsb and 5+.
So, before I start to take of "Мультик" , transistors, and other suspicious peaces does somebody have idea for quick repair or I have to do it on old fashion way:)

Jega писал(-а):
Mobo is not starting up even on force
Mobo is not starting or power supply is not starting on force?

Jega писал(-а):
On PS_ON there is 0.8V
PS_ON is PWR_ON (PWR_SW) on front panel connector?
Is you measured voltage on PS_ON (power supply) and +5VSB (power supply)?

Аватар пользователя Jega

You are right! It`s pwr_sw on front panel not PS_ON on ATX connector who have 0.8V.
Mobo is not starting by pressing pwr_sw on front panel (the reason is obvious-0.8V on it).When I try to force it to start by shorting "green&black" wire on ATX connector with supply present nothing hapend.MOBO is dead!
The main problem is with +5 on USB-s who have shortcut to null.

Jega писал(-а):
The main problem is with +5 on USB-s who have shortcut to null.
+5 V on USB have jumper switch or transistor switch (+5VSB --> USB power <-- +5V)? Fuse is present?

Аватар пользователя Jega

I didn`t saw any jumpers for USB supply. I`ll search for fuse or transistors on it and reply the result...

Аватар пользователя Jega

Problem is solved:
I found Q2 (D408 N-Channel Enhancement Mode Field Effect Transistor - Alpha & Omega Semiconductors) in short cut. After desoldering him MOBO start to boot normaly. I`m not sure what is his purpose on this board and where it`s connected becouse I found him to be bad with very much luck (by accident:) ). I`ll try to locate what`s he doing and to write out...
Thank`s Maco!

Аватар пользователя Jega

The final result of investigation is: Main cause of mailfunction is Q2, but Shortcut on +5 USB voltage to null remained. Then I did something I should do at the first, to look on rear panel USB ports. One of them was slightly demiged with +5V pin sliped to chasis of connector. That was reason of shortcut. I changed whole connector just to be safe.
P.S. Capabilitiy of users to ruin MOBOS are infinite:)

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