LG RZ-37LZ55 stuck in Standby

[Chungalin]

I’m stuck too with this one.

Red Standby LED on. Doesn’t power on from keyboard nor remote. ST_5V (5V standby power) correct. ON/OFF signal to PSU is always 0V (so it’s normal that power supply doesn’t start other voltages). PWR_ONOFF signal from CPU is 3V, and this brings Q1001 to short ON/OFF with GND, so looks like it’s nothing from PSU (it looks good, nothing bloated, nothing blown and good ESR). Tried disconnecting all cables from PSU to MAIN, and shorting ST_5V with ON/OFF. Relay clicks, so it looks that PSU would power on if CPU could activate it.

IR receiver signal present on MAIN connector from front PCB. Keyboard has 3V and reacts to Power keypress.

So, to me, looks like a MAIN problem. Anything I can do?

[fpsousa]

Re: LG RZ-37LZ55 stuck in Standby

Hi
Yes, it seems to be the CPU chip that don´t produces the on/off signal.
Has you measure the crystal clock frequency? and the voltages on main that suplies the CPU?
Sometimes the eeprom must be exchanged and sometimes is a problem off firmware.

[Chungalin]

Re: LG RZ-37LZ55 stuck in Standby

Other small voltages (3.3V, 1.8V...) were correctly generated from the ST_5V.

I’ve dismissed this one, no time to keep messing with it. Thanks for the help.

[sordids999]

Re: LG RZ-37LZ55 stuck in Standby

http://www.ebay.co.uk/itm/LG-RZ37LZ5...AAAOSwqu9VGdDu

7 Piece REPAIR Kit for LG RZ37LZ55 Power Board 6709900002A 6870TD30D10 EAY33043001 Repair Kit.


Fixes the following symptoms:
-stuck in standby
-won't come on
-dead