phillips lcd keeps blowing fuse

[budm]

Re: phillips lcd keeps blowing fuse

OK, I found the micro controller that generate the Dimming signal, it is IC3301 on the main board. I wonder if you can do some kind of factory reset to make this pin working again or not. Found it after looking at page 47 and trace out the signals to page 53.
philips_40pfl3505df7_chassis_pl10_5.pdf

[Mark369]

Re: phillips lcd keeps blowing fuse

My board keep blowing fuses becasue D1208 was shoted. It's a 200V 1w Zener near
IC1201

[budm]

Re: phillips lcd keeps blowing fuse

OK, I could not download the spec of the panel without sign up at the Chinese web site, but I was able to print out the info on the inverter. The PWM pin 14 is the external dimming control with the typical AC frequency of 150Hz, and no shutdown or flicker at 10% @150Hz. I does not indicate if there is no signal (0V) what will happen.
So at this point, it seems that the main board is not sending to controlling pulses for dimming control of the inverter. We need to look for the correct diagram to troubleshoot the PWM DIMMING circuit on the main board. The panel does not use pin 13 for the Analog lamps brightness adjust.

[budm]

Re: phillips lcd keeps blowing fuse

Let me look up the spec of this panel first. I look at the diagram of this TV (supposedly to be the same as Emerson_LC401EM2F per MisterD that I was helping him on), that PWM_SEL is labeled as NU (not used) but it is used on your TV.
Can you tell me if the CN1801 on the power supply board is connected to the other board at CN2106?

[TimT]

Re: phillips lcd keeps blowing fuse

panel is LTA400HM01. So Budm this means the screen will be " full bright " with no way to ajust the brightness

[budm]

Re: phillips lcd keeps blowing fuse

It just mean that you lamps will be fully on.
Can you get the sticker on the LCD panel so I can look up the spec to find out how this inverter board is setup? It seems to be using active LOW logic. Most TV use analog for controlling lamp brightness.
I also still want to know how MisterD TV reacts at the PWM pin when he makes the backlights adjustment.

[TimT]

Re: phillips lcd keeps blowing fuse

I removed PWM_SEL and it works is it safe to use the Tv like this? did not feed 3v to BL_ADJ.. just removed PWM_SEL from connector

[budm]

Re: phillips lcd keeps blowing fuse

It is looking for pulse not steady DC on that PWM pin, so you are pulsing it when attach and remove the voltage.
OK, what you can do is to cut the wire for the PWM_SEL LINE and feed the 3V to the BL_ADJ instead and see if the lamp will stay on.
Most PWM signal will have min 10% pulse width to max of 90% pulse width.

[budm]

Re: phillips lcd keeps blowing fuse

The PWM_SEL is used in this TV, it is a Pulse Width Moduation type signal instead of using analog DC voltage 0-5vdc for controlling the lamp brightness on BL_ADJT pin. Since it is pulse type signal, depend on the kind of meter you have, it may not show anything.
What we can verify is to have MisterD make the brightness adjustment on the TV between minimum and maximum to see if his meter will change from XXX to XXX V.
Brightness control signals either analog or PWM should not turn the lamps off completely. MisterD can also disconnect this the PWM_SEL to see if the lamps will turn off.
We can also look up the LCD panel spec to see what the voltage should be for the inverter board.

[TimT]

Re: phillips lcd keeps blowing fuse

ok, I got it all setup and tested 2.9v but was having a hard time making a connection with the pins. burned the wire a little " wire is ok " but noticed voltage drop...so I was thinking BL-SW has 3v so I wired that to PWM-SEL. when I first make contact using BL-SW with PWM-SEL nothing. but as soon as I release the wire I get the flash of light. in other words as soon as I remove 3v from PWN-SEL I get the flash from lamps. don't know if this means anything?

[MisterD]

Re: phillips lcd keeps blowing fuse

If you want some other input from budm or tom66 before trying this I can private message them to get their opinion, I copy and paste the link to this page so they can click on it and come here to see.

Update! I did send a message to them both asking for their input.

[MisterD]

Re: phillips lcd keeps blowing fuse

It's like putting 2 batteries in a flashlight, the positive post from one battery touches the negative post of the other battery, the nipple end being positive and the negative end being flat, here's a picture diagram of two 6 volt batteries wired in series, just look at this as two 1.5 volt batteries wired like the picture and it will produce 3 volts, the nipples of the two AA Batteries would be facing to the left in the picture.

Black in picture is Negative to ground, the red would go to the PWM-SEL

Do you have flux for soldering? applying flux to the battery ends where you solder wires will make the solder stick better, if not apply solder to the wires prior to soldering them to the batteries.

"Heat the part not the solder"

[MisterD]

Re: phillips lcd keeps blowing fuse

It's like putting 2 batteries in a flashlight, the positive post from one battery touches the negative post of the other battery, the nipple end being positive and the negative end being flat, here's a picture diagram of two 6 volt batteries wired in series, just look at this as two 1.5 volt batteries wired like the picture and it will produce 3 volts, the nipples of the two AA Batteries would be facing to the left in the picture.

Black in picture is Negative to ground, the red would go to the PWM-SEL

[TimT]

Re: phillips lcd keeps blowing fuse

confirmed PWM-SEL is 0. are you sure about connecting -+ together? so just solder -+ at top and bottom " one battery will be upside down " then run two leads from each. any lead could be the ground?

[MisterD]

Re: phillips lcd keeps blowing fuse

Here are the readings from the mainboard connector and inverter connector.

main

tuner 35v is getting 39v
lcd 12
lcd 12
p+on 3.36v
+6.5vf or 1v gets 11v
p-on 3.5v or reg gets 6.70
p+ on 5v
24v for amp gets 27.8

inverter

power sel 0 "THIS SHOULD BE ABOUT 2.69 VOLTS" posted by MisterD 1/8/2013
bl adj is not used
bl 5w gets 3w
error 0
gnd
gnd
gnd
gnd
gnd
24v
24v
24v
24v
24v

not sure how to inturpet these results?
there is a 10amp SMF on inverter and it's getting 9.6 on both ends. inverter lights up for a split second thats when i see the " phillips " when inverter goes out the phillips is still there. then I see the no signal. this is extremely hard to see! I can ajust the sound/channels ect it works fine. menu works fine. powers off and on correctly. seems everything works fine just no backlight.

Look at this voltage again on the white connector on the power supply board.

PWM-SEL you say 0 volts, budm says that controls lamp brightness, I checked that voltage on my 40" Emerson that has the same power supply board as your old board, I have 2.69 volts here on pin PWM-SEL you have 0 volts, maybe that's why you don't have any backlight, please check this voltage again, if it is still 0 volts and it was my tv set I would take two 1.5volt AA batteries and solder a short wire from + of one battery to - of the other battery, then take a clip lead wire and cut it into, solder one of these to the - of the one battery and then the other to the + of the other battery, so you end up with two AA batteries wired in series with leads on each end to give you a 3 volt power source, hook the - (negative end) to chassis ground and hook the + (positive end) to the PWM-SEL pin on the power supply white connector using a safety pin to contact bare part of wire and then power on the TV set and see if you have backlights.

[TimT]

Re: phillips lcd keeps blowing fuse

it should work then... but I don't know what else to try anybody got any suggestions?

[MisterD]

Re: phillips lcd keeps blowing fuse

it says the part i got works with Philips LC407SS1 I have Philips 40PFL3505D/F7. The board look the same. same voltages printed on the boards are the same. the only difference that i can see are the diodes on the new board are larger " physically " around the bridge. im thinking about swapping them out. cant do no harm I can always use one as a core. MisterD I just dont know what to test on the power board. seems output is correct

I'm not sure where you got your Power Supply replacement board from but check this out, it says the replacement works with both Philips LC407SS1 and Philips 40PFL3505D/F7 depending on serial number.

http://www.shopjimmy.com/pandf-a01pempw-001-mpw-cba.htm

[TimT]

Re: phillips lcd keeps blowing fuse

tested plugged in and not either way 3v at BL-SW. and I agree with you more the one way to get the correct volatges. but this power board was not listed as a alternative to the orginal board. so i dont know....

[MisterD]

Re: phillips lcd keeps blowing fuse

looking closer at the board installed it has a large cap then the old board did not! boards seem the same.the hole for that cap is on my old board but never installed! assuming this board can work for other models. a guess a " generic board " that can be setup for different tv's. also another cap is installed on the new board. i think i can setup the new board just like the old one. strange it seems this board as is has the correct output.

painel# LTA400HM01

old board A01PNMPW 05810P00557
New board has no sticker ...... BA01POF01035

I had a replacement power supply board for a 47" Philips LCD that I was working on and it had a capacitor and one other component missing in comparing it to the old board but it still worked fine. since all the correct voltages are present I don't think that trying to set up new board to match the old one will remedy anything.

[MisterD]

Re: phillips lcd keeps blowing fuse

I see in post 92 that you are showing a picture of the way you tested the voltages from the power supply and the connector is Not plugged in, Please Make sure all connectors Are plugged in on all the circuit boards, leave them plugged in and test the BL-SW Voltage, if your probe won't make contact with the bare part of the wire you can use a safety pin by pushing it into the connector, check the voltage on both ends of the wire that goes from the power supply to the inverter board. with the TV powered on what voltage do you have at BL-SW connection?