Lg 50pj550 no STBY light

[dzyk2000]

Re: Lg 50pj550 no STBY light

So if you run the power supply board by itself without having it connected to other board but just the AC input, do you still get 390VDC on the main filter cap (measured right between the two legs of the cap, not chassis GND)

Yes, power supply is on my bench, is not conected on main board or ysus . I have 327v in input at T301, but nothing on the output. i changed again 3br1565 and now i have in pin3 1,5v, in pin 4 0,5v, pin 6 0.3v.

i dont understand why no have 5v (3.49v)

[budm]

Re: Lg 50pj550 no STBY light

So if you run the power supply board by itself without having it connected to other board but just the AC input, do you still get 390VDC on the main filter cap (measured right between the two legs of the cap, not chassis GND)

[dzyk2000]

Re: Lg 50pj550 no STBY light

Are you 100% certain they are off or does off mean off/removed from the board??

Yes, was checked out of board , im 100% . But i dont undrestand why have no voltage at EY317 T301
In D101 is no AC that mind rl101 is open

[Andrew F. Ali]

Re: Lg 50pj550 no STBY light

Are you 100% certain they are off or does off mean off/removed from the board??

[dzyk2000]

Re: Lg 50pj550 no STBY light

Thank you R_J and Budm.

R305 have 0.34 ohm, i think is ok.

I have no 17v, no 5v or 3,5 v
Can you have a look at this picture.
I dont know where need to start checking 5v fault.

3br1565
pin 1 drain - 327v
pin2 cs - 0V
pin3 BA - 0,1v
pin 4 VCC - 0,5V
pin6 fb - 0,1v

p813 have 0v on 17v pin, 5v pin, stby pin, ac det pin
error det 0,1v

Power Supply Basic Operation AC Voltage is supplied to the SMPS Board at Connector SC101 from the AC Input assembly. Rectified by the Bridge rectifier D101 generates a primary B+. The Power factor circuit generates a Primary supply which can be read at Fuse F302 160V. This primary voltage is routed through T301 and routed to the Standby 5V supply. The STBY5V (standby) is B+ for the Controller chip on the back of the board (IC701) on the SMPS and output at P813 pins 13 and 14 then sent to the Main board for Microprocessor (IC1) operation (STBY 3.49V RUN 5.23V). When the Microprocessor (IC1) on the Main Board receives a “POWER ON“ Command from either the Power button or the Remote IR Signal, it outputs a high (2.43V) called RL_ON at Pin 15 of P813. This command causes the Relay Circuit to close both Relays RL101 and RL103 routing AC to the Bridge Rectifier D101 which then routes the primary voltage to the PFC circuit (Power Factor Controller) 390V which can be read measuring voltage at Fuses F302 (390V)

I have 390 v with rl101 and rl103 off, why?

[dzyk2000]

Re: Lg 50pj550 no STBY light

Thank you R_J and Budm.

R305 have 0.34 ohm, i think is ok.

I have no 17v, no 5v or 3,5 v
Can you have a look at this picture.
I dont know where need to start checking 5v fault.

3br1565
pin 1 drain - 327v
pin2 cs - 0V
pin3 BA - 0,1v
pin 4 VCC - 0,5V
pin6 fb - 0,1v

p813 have 0v on 17v pin, 5v pin, stby pin, ac det pin
error det 0,1v

[budm]

Re: Lg 50pj550 no STBY light

1) In standby with TV just plugged into the out, the DCV on the top pin of the transformer in your picture should be about incoming ACV x 1.414, so if your AC is 230VAC then the DC V will be about 352V DC.

2) The DCR of the transformer will be really low resistance, most of the time will <1 Ohm, you can only use Ohm meter for checking for open winding.

3) Your drawing of the connection of PIN 2 does not look right, that is the CS which should be connected to the very low Ohm current sensing resistor and Ground. Look at the application circuit in the spec sheet to see how each pin of that SMPS IC is connected.

4) c310 is connected to BA (pin 3), see page 17 about the cap connected to that BA pin.

https://cdn.badcaps-static.com/pdfs/...64ff9dcede.pdf

[R_J]

Re: Lg 50pj550 no STBY light

Did you check R305? what resistance did you measure?
The transformer is likely ok and the DC resitance of the windings will very low. You do know these circuits operate at high frequency, 67kHz, your meter will not measure that.
Do you have any standby VOLTAGE, it should be around +5 volts
C310 is also very likely ok
They do have repair kits for this board

[dzyk2000]

Re: Lg 50pj550 no STBY light

Hello everyone.

Where can I find a list of smd capacitor for EAY60968701?
I suspect that c310 is defective

I changed 3br1565jf ... but I had a short circuit after the soldering. I checked all the nearby components and are good. It replaced 3br1565jf with a new one, but I have no voltage, except in the drain pins 3br1565jf and in the first coil of the T301. no voltage between pin 4 and 5 of 3br1565. I have no voltage on the secondary coil at T301. I need some help. Thank you.

UPDATE
Who can help me with the t301 measurement, I want to know what resistance have primary and the secondary coils and what voltages needs to have at the entrance and exit when they are in stby

[dzyk2000]

Hello everyone.

Where can I find a list of smd capacitor for EAY60968701?
I suspect that c310 is defective

I changed 3br1565jf ... but I had a short circuit after the soldering. I checked all the nearby components and are good. It replaced 3br1565jf with a new one, but I have no voltage, except in the drain pins 3br1565jf and in the first coil of the T301. no voltage between pin 4 and 5 of 3br1565. I have no voltage on the secondary coil at T301. I need some help. Thank you.