LG TV 47LW5500 does not power on (PSU EAX62865401/Main board EAX64405501)

[mohsinrizwan]

Re: LG TV 47LW5500 does not power on (PSU EAX62865401/Main board EAX64405501)

full board pictures attached

[mohsinrizwan]

Re: LG TV 47LW5500 does not power on (PSU EAX62865401/Main board EAX64405501)

Bump
anyone got idea what's wrong with it why its not getting full voltage or activating 12/24V supply

[Diah]

Re: LG TV 47LW5500 does not power on (PSU EAX62865401/Main board EAX64405501)

i response to you as first one and wrote that you listed wrong voltage.. its hard to to any one following if the OP do some things wrong.
so let from start just do this 2 things no more.

all test the power boards should be out from the TV testing as stand alone
- don't use any external resistor, solder jumper between stand by 3.5V and power on

now read the voltage on the main cab and the voltage on the out put socket

[budm]

Re: LG TV 47LW5500 does not power on (PSU EAX62865401/Main board EAX64405501)

Bump
anyone got idea what's wrong with it why its not getting full voltage or activating 12/24V supply

1) You gave 220VAC at the two AC legs of the bridge rectifier, but your meter only shows 287VDC on the main filter caps instead of around 310VDC.

2) The Voltage on the main filter cap should jump to around 380 ~ 400VDC when PS-ON is applied to turn on the PFC circuit and the 12/24VDC power supplies.

3) The 12V/24V power supplies will not run unless PFC Boosted Voltage is present, if the PFC Voltage is low, the 12V/24V will stay in shutdown.

I attach the picture of the HOST SIDE power supply to show you the path of the circuit, you need to check the bridge rectifier, the two PFC Diodes, the resistance path all the way to the main filter cap to see why your meter only shows 287VDC, we need to get over 300V for the PFC to run, the PFC circuit may be in shutdown due to low Main DC Voltage.
You also need to see if there is switched VCC for running the PFC IC, so get the P/N of the PFC IC and look up the spec sheet to locate the VCC pin of the PFC IC.
Notes: the troubleshooting is being done based on the meter is OK per OP.

[mohsinrizwan]

Re: LG TV 47LW5500 does not power on (PSU EAX62865401/Main board EAX64405501)

@Diah I didn't meant int hat way I know you responded first on my thread and I apologize if you felt like I was saying noone responded to me.

@Budm thanks for detailed info, i'll check all component and update here.