Lg 50pj550 no STBY light

[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.

[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

[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

[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

[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

[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?

[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

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

[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

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

Without having the board connected to other board and have Voltage on the main filter caps in the PFC circuit is that relay RL101 has to be closed, so you should verify that is no DC on the coil (measure right across the coil) of RL101. If the coil Voltage is not present then it mans the contact is stuck closed. RL103 is used for bypassing the NTC when PS-ON is present.
What DC V do you have between C377?

"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." That is wrong. Where did you get the info from?

[budm]

Re: Lg 50pj550 no STBY light

Is this your EXACT board?

[budm]

Re: Lg 50pj550 no STBY light

"i dont understand why no have 5v (3.49v)" I do not understand the (3.49V). What is the 3.49V reading?
The 5.1V (switched Q352) and the 17V (switched Q356) are switched power supplies.

[dzyk2000]

Re: Lg 50pj550 no STBY light

Without having the board connected to other board and have Voltage on the main filter caps in the PFC circuit is that relay RL101 has to be closed, so you should verify that is no DC on the coil (measure right across the coil) of RL101. If the coil Voltage is not present then it mans the contact is stuck closed. RL103 is used for bypassing the NTC when PS-ON is present.
What DC V do you have between C377?

"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." That is wrong. Where did you get the info from?

After t301 i have no voltage, betwen pins of c377 i have 0v, relay is mounted without black cover to see whats hapening, n the picture above, where I wrote the voltage of 3.7 v. this voltage starts at 1v and increases if there is more time connected. I do not have the ac voltage in d101 but on the output I find the tension I am talking about above

[dzyk2000]

Re: Lg 50pj550 no STBY light

"i dont understand why no have 5v (3.49v)" I do not understand the (3.49V). What is the 3.49V reading?
The 5.1V (switched Q352) and the 17V (switched Q356) are switched power supplies.

this is the text from training manual.

Power Suration 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) and F801 (389V) from “Hot” Ground. AC Detection (AC Det) is generated on the SMPS, by rectifying a small sample of the A/C Line and routed to the Controller (IC701) where it outputs at P813 pin 16 (4.45V) and sent to P301 to the Main Board where it is sensed and monitored by the Main Microprocessor (IC1). If AC Det is missing the set will come on, but shut off in 10 seconds. When RL_ON arrives, the run voltage +5V source becomes active and is sent to the Main Board via P813 (5.24V at pin 5, 6 and 7). The (Error Det) from the SMPS Board to the Main Board can be measured at pin 8 of P813 (2.88V STBY and 4.93V RUN), but it is not used. The RL-ON command also turns on the 17V (Audio B+ 16.79V) which is also sent to the Main Board. The 17V Audio supply outputs to the Main board at P813 pins 1 and 2 and used for Audio processing and amplification. The next step is for the Microprocessor IC1 on the Main Board to output a high (3.27V) on M_ON Line to the SMPS at P813 Pin 17 which is sensed by the Controller IC701, turning on the M5V line and outputs at P811 pins 9 and 10 to the Y-SUS board. The Controller (IC701) also uses the M_ON line to turn on the VA and the VS supplies. (Note there is no VS On Command in this set). VS is output at P811 to the Y-SUS board P201. (VA pins 6 and 7 and VS pins 1 and 2). Note: The Va is fused on the Y-SUS then routed out P209 to the X-Board Left. VS is also routed out of the Y-SUS P206 pins 1 and 2 to the Z-SUS P2. AUTO GND Pin 18 of P813: This pin is grounded on the Main board. When it is grounded, the Controller (IC701) works in the normal mode, meaning it turns on the power supply via commands sent from the Main board. When AUTO GND is floated (opened), it pulls up and places the Controller (IC701) into the Auto mode. In this state, the Controller turns on the power supply in stages automatically. A load is necessary to perform a good test of the SMPS if the Main board is suspect

[budm]

Re: Lg 50pj550 no STBY light

If there is no AC feeding the bridge D101 then there is no way you can have that 390VDC on the main cap.

[budm]

Re: Lg 50pj550 no STBY light

"Fuse F302 160V" But you have 327VDC, right?

[dzyk2000]

Re: Lg 50pj550 no STBY light

"i dont understand why no have 5v (3.49v)" I do not understand the (3.49V). What is the 3.49V reading?
The 5.1V (switched Q352) and the 17V (switched Q356) are switched power supplies.

q352 and q356 are not powered by t301?

[dzyk2000]

Re: Lg 50pj550 no STBY light

"Fuse F302 160V" But you have 327VDC, right?

yes

[budm]

Re: Lg 50pj550 no STBY light

RL_ON is 0V, correct?