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)

@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.

[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.

[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

[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

[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)

sorry I went to sleep, i'll post whole board pic shortly.

Bridge rectifier had 220V in inner legs, that was first thing I checked after relay click.
i'l measure reading again with different meter.

[budm]

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

BTW, check the AC Voltage on the two inner legs of the bridge rectifier to see what you get.
It's 1:40 AM my time here so I will have to do follow up tomorrow, may be some one will look over also and help you out. Good night.

[budm]

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

I put red prob on positive of cap

I hope these pictures are usefull

Are you sure the meter is good on 1000V scale?
The pictures are much better but can you show the whole board, it is hard for me to trace out the circuit without seeing the whole board.

[mohsinrizwan]

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

I put red prob on positive of cap

I hope these pictures are usefull

[budm]

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

https://www.badcaps.net/forum/attach...9&d=1596433739
I need straight shots pictures of the board, not in angle like that, because I need to be able to trace out the traces on the board to see what is going on.

[budm]

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

https://www.badcaps.net/forum/attach...8&d=1596433739
I only see Black probe on Neg. leg of the cap. Where did you put the red probe at?

[mohsinrizwan]

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

275VDC on the main caps is not right all.
Can I see good clear straight shots of the whole bottom side of the power supply board?
BTW, do you hear the power relay clicks on when you apply the force on (jump)?

forget to mention relay click, yes I do hear relay click sound and I verified rectified has same 275-278VDC with force on

[mohsinrizwan]

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

attached

[budm]

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

yes its 275V (sometimes it goes to 278/285) and yes I am on 230V
with force off I am getting same 275V

275VDC on the main caps is not right all.
Can I see good clear straight shots of the whole bottom side of the power supply board?
BTW, do you hear the power relay clicks on when you apply the force on (jump)?

[mohsinrizwan]

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

yes its 275V (sometimes it goes to 278/285) and yes I am on 230V
with force off I am getting same 275V

[budm]

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

all three caps has 275V and fuse it fine

That is very low.
What is your AC line Voltage, 230V? If it is 230V you should have about 325V when not force on, about 380 ~ 400V when forced on.
Are you sure you're only getting 275Vdc?

[mohsinrizwan]

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

all three caps has 275V and fuse it fine

[budm]

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

My apologies yes PS-ON had 3.5V it was my typo. and yes I did disconnected cable from main board and used resistor to jump PS-ON to 3.5V

only voltages I am getting is 3.5V on Pins 9-12 (and get 3.5V on PS-ON when jumped)

OK.
So if you run the power supply board by itself, you jump the PS-ON pin but the switched 12V/24V still do not come on, we need then to find out if the PFC Voltage booster is working or not next.
Please check the Voltage between the two legs of the main filter caps (the three of them with 450V rating), they should have about 380 ~400VDC when you jump the PS-ON.
BTW, there are 3 fuses (1 for ac, 1(with two dark color bands) for 12V/24V power supply, 1 for standby power supply. Is the one for 12V/24V OK?

[mohsinrizwan]

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

If you jump PWR-ON to 3.52V STBY, why does it show PWR-ON = 0V?
When you jump it, did you disconnect the cable from the power supply to the main board first? If you did not you can damage the switched Transistor on the main board.
You should always use the resistor to force on the board, in this case you can use 100 ~ 500 Ohms resistor.

My apologies yes PS-ON had 3.5V it was my typo. and yes I did disconnected cable from main board and used resistor to jump PS-ON to 3.5V

only voltages I am getting is 3.5V on Pins 9-12 (and get 3.5V on PS-ON when jumped)

[budm]

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

Hello,

My LED died while checking on PS-ON test not seeing any voltage.

Here is result on PS-ON Pin 1 jump to Ping 9-10-11 or 12 (3.5V)

23 - N.C -> 0V | 24 - ERROR -> 0V
21 - 12V -> 0V | 22 - PWM -> 0V
19 - 12V -> 0V | 20 - N.C -> 0V
17 - 12V -> 0V | 18 - DRV-ON -> 0V
15 - GND -> 0V | 16 - VSYNC -> 0V
13 - GND -> 0V | 14 - GND -> 0V
11 - 3.5V -> 3.52V | 12 - 3.5V -> 3.52V
9 - 3.5V -> 3.52V | 10 - 3.5V -> 3.52V
7 - GND -> 0V | 8 - GND -> 0V
5 - GND -> 0V | 6 - GND -> 0V
3 - 24V -> 0V | 4 - 24V -> 0V
1 - PWR-ON -> 0V | 2 - 24V -> 0V

If you jump PWR-ON to 3.52V STBY, why does it show PWR-ON = 0V?
When you jump it, did you disconnect the cable from the power supply to the main board first? If you did not you can damage the switched Transistor on the main board.
You should always use the resistor to force on the board, in this case you can use 100 ~ 500 Ohms resistor.