philips 42pfl5432d got sound no backlight

[retiredcaps]

Re: philips 42pfl5432d got sound no backlight

OK, I look at the INVERTER ON/OFF picture in post11, you do have BL_ON (>3.3V = ON) signal correctly feeding your inverter board, please see my explanation in the picture.

Hmm, that is what I thought as per post #9, but then that other screenshot threw me totally off.

[budm]

Re: philips 42pfl5432d got sound no backlight

Look for little black fuse as shown in the picture, very hard to locate on the board because it looks like resistor. CHI-MEI uses this kind of fuse a lot for supplying the voltage to the inverter PWM IC.

[retiredcaps]

Re: philips 42pfl5432d got sound no backlight

Ahh, I found it thanks to budm's knowledge. I'm sure if selldoor wasn't missing from this thread, he would have already suggested it.

Myself, I have neither the experience or eyesight.

The insistence of clear focused photographs comes through again.

[budm]

Re: philips 42pfl5432d got sound no backlight

I know selldoor has real good set of eyes. The picture is an example only, I cannot see it in the pictures in post 1 because they are really out off focus, he will need to look at both inverter boards.
The inverter boards are really cheap!

[retiredcaps]

Re: philips 42pfl5432d got sound no backlight

I took allsmith's picture #2 in post #2 and circled the fuse and uploaded to post #23. Allsmith's is a F1 with a 30 on it. A 1.5A/76V fuse.

It is funny because that is the picture I used to see BLON was pin 14. If I would have looked a bit closer, I would have noticed the F1 fuse right away. But, I'm not selldoor!!

[budm]

Re: philips 42pfl5432d got sound no backlight

Ahh, I did not see picture in post2, now it is nice and clear! It still amazed me that shojimmy can sell both boards for $50, all the transformers on the board worth more than 50 bucks.
Follow-up, he did check this tiny fuse already in post 6:
"Also there is one more fuse on master board.its a 15a 76 v tested 0.6 ohms meter set to 200 ohms in circuit. Its tiny!!"

[retiredcaps]

Re: philips 42pfl5432d got sound no backlight

Follow-up, he did check this tiny fuse already in post 6:
"Also there is one more fuse on master board.its a 15a 76 v tested 0.6 ohms meter set to 200 ohms in circuit. Its tiny!!"

Well, that proves it. I'm dead tired and off to bed now.

One of my best friends is getting married tomorrow so I have been a little distracted the last few days.

[allsmith]

Re: philips 42pfl5432d got sound no backlight

Ok sorry about not posting the inverter test numbers ,i'll post a pic with all the #'s

just so you know my dmm is a very cheap one but its new.
The tests where done with the dmm set to 20k setting.

Also blon does pass through the power supply board,
it comes through from the connector that comes from the main board(red in pic) through the power supply over to the two inverter connectors(blue in pic)
sorry about the bad pics,I just bought a new 14 mp camera for this stuff and not getting the hang of it yet, The camera on my razr smart phone still seems better???

[allsmith]

Re: philips 42pfl5432d got sound no backlight

I did check the 15a 76 v fuse..tested 0.6 ohms meter set to 200 ohms in circuit.
I did not check to see if there is voltage on each side of it in fear of slipping and shorting something! but i can if you guys think i should.

Also i dont think this matters but sombody else worked on power supply before i got the tv, The two connectors that go to the inverters can be plugged in to either port.Maybe they got them backwards??
I marked them the way i found them.

looking at pin out screenshot looks to me like it wouldnt matter,but im not sure.

[budm]

Re: philips 42pfl5432d got sound no backlight

The two 24V connectors in parallel are normal, they do that all the time to allow to use the power supply for TV with single inverter or TV with two inverters. They route the BL_ON, Dimming signals through the power supply board so the wiring bundle will be cleaner, very normal practice.
Do you get any DC voltage on the IC's on the Inverter board? That very small fuse supply the voltage to the IC's, it may goes through some regulator of some sort to drop the 24V down for the PWM IC, that will be the next thing to check.

[allsmith]

Re: philips 42pfl5432d got sound no backlight

Do you get any DC voltage on the IC's on the Inverter board? That very small fuse supply the voltage to the IC's, it may goes through some regulator of some sort to drop the 24V down for the PWM IC, that will be the next thing to check.

I checked the fuse,it has 24v on both sides.
Not sure what Ic's you want me to check,i'll post some pics if you want to point them out.

Also double checked voltage on Blon and its 3.2v not 3.3v like i first thought,dont know if that would make any difference.

Also the only thing i can think of,not sure if it would matter or not,is the general purpose caps that the original owner put in the power supply before i got the tv.

Could the voltage be unstable do to the illinois capacitors ckh series??

Thanks!!

[budm]

Re: philips 42pfl5432d got sound no backlight

3.2~3.3VDC should be more than enough to turn on the inverter, you can verify that by looking up the spec of the LCD panel, it will give you the details spec of the T-CON, INVERTER boards voltages spec.
As far as the IC voltages are concern, there should be voltages on at least one pin for the VCC for it to run.
U1 looks like a 5V regulator, then check U2, U3 next to it to see if it has 5v feeding them, and then the U31, U4 also. You can look up the spec to see which pin is the VCC pin.

[allsmith]

Re: philips 42pfl5432d got sound no backlight

[QUOTE=budm;261108]3.2~3.3VDC should be more than enough to turn on the inverter, you can verify that by looking up the spec of the LCD panel, it will give you the details spec of the T-CON, INVERTER boards voltages spec.
As far as the IC voltages are concern, there should be voltages on at least one pin for the VCC for it to run.
U1 looks like a 5V regulator, then check U2, U3 next to it to see if it has 5v feeding them, and then the U31, U4 also. You can look up the spec to see which pin is the VCC pin.[/QUOTe

Remember im a newbie here lol,And this tiny stuff has me a bit worried i will short something out with my test probe,But i'll give it a go.

So u1 should be the first one i check?
should i look up the part number first to see what pin to test?

u1 i feel a little more comfortable with as its pins are decent size,but the other Ic's! man how do you only touch one pin at a time? microscope!!lol

If you can help me test u1 here first,then we can go from there to the IC's

I really appreciate your time!!! And expertise!!! thank you!!!

[budm]

Re: philips 42pfl5432d got sound no backlight

We can start with that regulator U1 first since it is big. It has 3 connection, with black probe to ground, then use Red probe to read each pins, label the pin as 1, 2, 3 and report the reading.

[allsmith]

Re: philips 42pfl5432d got sound no backlight

We can start with that regulator U1 first since it is big. It has 3 connection, with black probe to ground, then use Red probe to read each pins, label the pin as 1, 2, 3 and report the reading.

pin 1= 24.4v
pin2=4.9v
pin3=00.0v

I,ll start looking up part#'s for the IC data sheets

[retiredcaps]

Re: philips 42pfl5432d got sound no backlight

pin 1= 24.4v
pin2=4.9v
pin3=00.0v

I,ll start looking up part#'s for the IC data sheets

U1 is working fine. It is 78M05.



Max input is 35V and obviously output is 5.0V. At 4.9V, it is 2% off spec, but the datasheet it can be between 4.8 and 5.2V.

Are there more digits after 4.9? Resolution (the number of digits) matters.

Move onto the next set of ICs.

[allsmith]

Re: philips 42pfl5432d got sound no backlight

U3 IC pinout
I was hoping just the candle in the back blew out and it just needed relit!!LOL

[allsmith]

Re: philips 42pfl5432d got sound no backlight

u1 is working fine. It is 78m05.



max input is 35v and obviously output is 5.0v. At 4.9v, it is 2% off spec, but the datasheet it can be between 4.8 and 5.2v.

Are there more digits after 4.9? Resolution (the number of digits) matters.

Move onto the next set of ics.

pin 2=4.98

[allsmith]

Re: philips 42pfl5432d got sound no backlight

Also i can here a tiny click around the IC's when i hit the power button

[budm]

Re: philips 42pfl5432d got sound no backlight

Clicking sound?