Lg 50pj550 no STBY light

[mmartell]

Re: Lg 50pj550 no STBY light

Not sure if this pertains to your situation or not. I just repaired a 50PJ550 by replacing a single 10 ohm power resistor that went open.

http://www.coppelltvrepair.com/p/639...ing-on-and-off

[dzyk2000]

Re: Lg 50pj550 no STBY light

Up, need some help please.

[dzyk2000]

Re: Lg 50pj550 no STBY light

Hi again, Please i need some advice.
I connected the board as in the training manual with 2 bulbs of 100 watts between the vs and the ground. I made straps between rl-on / stby and m-on / stby with a 100 ohm resistor and between gnd and autognd. the bulbs illuminate for a few seconds and burn again zd 301.

[dzyk2000]

Re: Lg 50pj550 no STBY light

https://www.youtube.com/watch?v=UWJltRjRyZo

[dzyk2000]

Re: Lg 50pj550 no STBY light

Update:

I found c311 burnt. I removed the capacitor and now without it I have normal standby voltages but the red LED is off . where can i find the list of smd capacitors values? on the schematic are not noted.

I need to know the value of c311 and c310.

P813 In stby: relay click just one time (3 sounds normal i think)

17v pin 0v
5.1v pin 0.69v
er det pin 1.69/1.72v
stby pin 3.50v
ac det pin 0v
m-on pin 0v
rl-on pin 0v

P813 With main board conected: relay clicking noise repeatedly.

17v pin 0v /17 v when relay click
5.1 pin 0.69 /0.72
er det pin 1.69 / 3.72 when relay click
stby pin 1.62 all the time
ac det pin 0v / 3.90 when relay click
m-on pin 0.3 all the time
rl-on pin 1.40 all the time

[dzyk2000]

Re: Lg 50pj550 no STBY light

Any idea please?

[dzyk2000]

Re: Lg 50pj550 no STBY light

I tried with 4 different ic and i have same result. I don't understand why don't open cell, i have 1,2v in ba and 0.60 in vcc

[budm]

Re: Lg 50pj550 no STBY light

gnd to pin 1 is more than 20Mohm or is error measure
gnd to pin 2 is more than 20Mohm or is error measure
gnd to pin 3 10Mohms
gnd to pin 4 15kohm
gnd to pin 6 2.30 Mohms



just f302 blow up, ic still look good,

Looking at the spec sheet, the cap will be charge up with 0.9mA current source so to get 18V, the resistance has to be at least 20K Ohms. So something is still not right at VCC pin. Right now you are are getting 0.5V so that tells me the internal charge pump is not working at all.

[budm]

Re: Lg 50pj550 no STBY light

The main key point right now is that the internal charge pump inside the IC has to charge up the cap on VCC pin to 18V for the circuit to startup. So I hope your replacement IC is good.

[dzyk2000]

Re: Lg 50pj550 no STBY light

Well, what happen when you power up board after fixing the solder joints?

Same result. Thanks a lot for help, I have to stop because it's 2 o'clock at night and I can not be careful. Tomorrow start again. Thank you very much.

[budm]

Re: Lg 50pj550 no STBY light

Well, what happen when you power up board after fixing the solder joints?

[dzyk2000]

Re: Lg 50pj550 no STBY light

So bad solder joints?
You might as well check the rest of the pins also.

so the soldering was ok, just that was the tight space and I probably got my hand off the pine

[budm]

Re: Lg 50pj550 no STBY light

So bad solder joints?
You might as well check the rest of the pins also.

[dzyk2000]

Re: Lg 50pj550 no STBY light

You can easily verify that by checking the resistance between pin 2 against each pin of the resistor.

is allright now 0.36 ohm

[budm]

Re: Lg 50pj550 no STBY light

You can easily verify that by checking the resistance between pin 2 LEG (not the solder pad that pin 2 is soldered on to) against each leg of the resistor.

[dzyk2000]

Re: Lg 50pj550 no STBY light

So why do you report the reading on pin 2 as:
"gnd to pin 2 is more than 20Mohm or is error measure" Check the solder connection between pin 2 and that resistor (R305), it sounds like you do not have connection between pin 2 and the leg of the resistor. Damaged trace?

trace is good, now i will reheat solder conections.

[dzyk2000]

Re: Lg 50pj550 no STBY light

allready checked all the nearby parts, nothing damaged, can be something tired but looks good on test.

[budm]

Re: Lg 50pj550 no STBY light

yes is 0.36ohm

So why do you report the reading on pin 2 as:
"gnd to pin 2 is more than 20Mohm or is error measure" Check the solder connection between pin 2 and that resistor (R305), it sounds like you do not have connection between pin 2 and the leg of the resistor. Damaged trace?

[dzyk2000]

Re: Lg 50pj550 no STBY light

"gnd to pin 2 is more than 20Mohm or is error measure" That is CS pin where the <1 Ohm Source resistance is connected to, so that reading is not correct. I thought you had already verify that the resistor connected between CS pin and GND is OK.

yes is 0.36ohm

[budm]

Re: Lg 50pj550 no STBY light

"gnd to pin 2 is more than 20Mohm or is error measure" That is CS pin where the <1 Ohm Source resistance is connected to, so that reading is not correct. I thought you had already verify that the resistor connected between CS pin and GND is OK.
I also indicated that your drawing on post 1 is wrong regarding to pin 2 (CS) pin.