Philips 19pfl3505d/f7 - No Power - Voltages drop

[caphair]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

KEY-IN1 goes from CN102 (4) to CN302 (29) Then to CN3702 (29), R3703 (100ohm) then to IC3301 (AC5) [page 57]
I think you mixed up CN3702 (pin29) KEY-IN1 with CN3701 (pin29) VCOM-PWM
I don't know how "this tv" works, but sometimes they turn on the power supply at initial power on to make sure all voltages etc are there and ok, then turn it off again and wait for the power on to be pressed.

Thanks I mixed it up only with identifying the connector. At cn302 pin 29 I get no voltage and no continuity to cn102 pin 4 where there is 3.3v

Do you see any component in between the two connectors? I can't find any and if there isn't then it's odd that I'm missing 3.3v at cn302

[R_J]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

If you follow it on the board view [page 64] it does connect directly, maybe inspect the plugs and connectors for a problem, sometimes the foil can break or get folded back on those ribbons, also on cn102, make sure a wire did'nt brake or get folded over.
It could be that all that is missing is the power on command getting to the micro

[caphair]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

There’s no conintiinty at all from the two points of the PCB even with the ribbon and plug disconnected.

Should I try soldering a jumper wire?

[R_J]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

I would'nt in case you get the wrong pins. there is a continous trace that connects the two pins, place one probe on cn102 pin 4 then with the other probe check the trace, push the probe tip through the coating to contact the foil trace, then follow the trace along the board probing that trace untill you find the open
Just to make sure we are on the same page

[caphair]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

Ok this is weird, I ran a jumper from cn102 pin 4 to cn302 pin 29 the exact ones you show in the pictures and with the jumper wire the 3.3v goes away this is with and without mainboard connected.

Soon as I remove the jumper 3.3v comes up. I double checked to make sure it was the right pins and marked with a marker before connecting the jumper

[R_J]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

Is pin 29 shorted to ground?

[caphair]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

Is pin 29 shorted to ground?

It's not. I even tried diode mode, positive lead on ground and black lead at the pin and it gives an OL reading

[R_J]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

If its not shorted to ground, how can it kill the 3.3 volts? trace that copper trace on your board, maybe it is different that the service manual?

[caphair]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

If its not shorted to ground, how can it kill the 3.3 volts? trace that copper trace on your board, maybe it is different that the service manual?

It's the exact same. I'll try what you suggested by tracing and scraping the trace. Very odd though when I had the jumper all the other 3.3v remained on cn102 only pin 4 went to 0v

[caphair]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

Wait a minute I checked pin 29 from underside of the board to ground and it appears shorted. If I measure from the top I get no beep to ground

Ok so how can pin 29 be shorted if at pin 4 of cn102 the 3.3v is present and the two pins are tied together?

[budm]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

Wait a minute I checked pin 29 from underside of the board to ground and it appears shorted. If I measure from the top I get no beep to ground

Ok so how can pin 29 be shorted if at pin 4 of cn102 the 3.3v is present and the two pins are tied together?

Beeping of the meter does not mean you have shorted circuit, the important information is the resistance reading, beeping means you have continuity between two points, your meter will probably beep with resistance as high as 50 Ohms (see your manual).

[caphair]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

Problem solved!

Pin 29 was touching the ground pin near it by a whisker or something. I cleaned it up with soldering iron and then redid my jumper from pin 4 of cn102 and tv powered up.

So if anyone has this model check that trace it breaks somewhere. For me I’m just going to solder a wire underneath and hot glue it.

R_J thanks a bunch for your help on this one. Appreciate it

[R_J]

Re: Philips 19pfl3505d/f7 - No Power - Voltages drop

Your welcome, glad I could help. and glad its working.