phillips lcd keeps blowing fuse

[TimT]

Re: phillips lcd keeps blowing fuse

the tv does not turn off. I can barely see the menu. ajusted brightness up..no change.

[MisterD]

Re: phillips lcd keeps blowing fuse

I assume you have the back off the TV and can't you see the backlight lit up? usually seen through the holes or slots in the metal chassis.

[TimT]

Re: phillips lcd keeps blowing fuse

No backlight! The " phillips " is on screen for about 3 seconds. but for the first half second its bright. i can still see it and the menu using a flash light at a angle... that's how hard it is to see it!

[MisterD]

Re: phillips lcd keeps blowing fuse

I just fixed a 47" Philips that was doing something similar, It would not shut off, the remote control did nothing, the backlights would come on for an instant then right back off, my problem was the Mainboard was not sending the signal to the Power Supply, replacing the Main Board also known as the Small Signal Board fixed my problem, there may be a way for you to make the backlights come on with an external 3v source, do you see a marking on the power supply board next to the white connector labeled BL_ON ?

[MisterD]

Re: phillips lcd keeps blowing fuse

I found a picture of a power supply board that is used for your Model TV, on the white connector I see a pin labeled BL-3V, the best way I found is to take a safety pin and shove it into that part of the connector to make contact with the 3V connection, then you need to take a reading with your meter set to DC Volts, hook the black prob to the chassis for ground and then touch the red prob to the safety pin connection to the BL_3V Pin and see what voltage reading you get, it should be near 3 Volts.

[TimT]

Re: phillips lcd keeps blowing fuse

I wii test this tomorrow. thank you

[TimT]

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
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.

[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
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.

Default 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
bl adj is not used
bl 5w gets 3w ? Is this possibly bl SW getting 3V ?
error 0
gnd
gnd
gnd
gnd
gnd
24v
24v
24v
24v
24v

[TimT]

Re: phillips lcd keeps blowing fuse

Sorry, you are correct bl sw 3v

[MisterD]

Re: phillips lcd keeps blowing fuse

I think that bl sw could be the same as bl_on which is at 3v and it seems like that would cause the inverter to fire up the backlights..can you hook your volt meter to this pin again and monitor the voltage? see what the voltage is when you first power on the TV, then leave the meter probe in place and see if this voltage stays constant, report your readings back here.

Hopefully budm and tom66 can help with this one. See Post#77, he has replaced the Power Supply Board.

[budm]

Re: phillips lcd keeps blowing fuse

OK, this TV uses:
PWM-SEL pin for lamp brightness control, it is being used by this TV.
BL-ADJ is the analog signal control for the lamp brightness, and it is not being used.
BL-SW is the same as BL_ON. You need to monitor this test point when the TV is plugged in but the power switch is not activated. Then hit the power switch and see if the voltage at this point changes state.
I believe you are getting the correct signal (3V as you had indicated).
I need to see good close up of the inverter board/s.

[TimT]

Re: phillips lcd keeps blowing fuse

When I plug this TV in it automatically starts up..no stand by. not shure if thats normal for this TV. I can turn it off with the power button I think that may put it in stand by?

when plugged in I hear the " click " from power board. bl SW is 0 then in about 3 seconds it jumps to 2.99 to 3.00v " this is when the backlight kicks in for a split second " it stays at 3v untill I turn the TV off with power button then bl SW is back to 0. I can turn it pack on with power button with the same results.

here are 3 pictures of inverter board. I will post another picture of the other board. and a picture of the way I tested this. Thanks for your help! on the picture labeled connect the connector 4p is getting 1.6v if i remember correctly.

[MisterD]

Re: phillips lcd keeps blowing fuse

I noticed in your pictures of the inverter board that some of the mounting screws are missing, all of the screws must be in place and tightened to ensure a good ground connection from the board to the chassis, this can cause this type of problem. you should make sure all circuit boards have all the mounting screws in place and are snugged down tight. Also it appears that there is something hanging off where the SMF (F1) is mounted to the board, has this fuse been replaced? make sure that is not something shorting to another connection on the board, I believe I saw a previous post about the voltage readings being the same on both sides of this fuse, maybe you should do a continuity check by measuring resistance on this fuse with the meter in both directions. set your meter to ohms on 200 scale. just 200 Not 200k or 200m, just 200 ohms.

[TimT]

Re: phillips lcd keeps blowing fuse

sorry, this does go into standby mode.. plugged in there is a " tick " but does not power up untill power button is pressed. more pictures

[budm]

Re: phillips lcd keeps blowing fuse

OK, the 3v is = Backlights on, and that signal is correct. So now we need to find out why the lamps turn off even though you do have the necessary voltage (24vdc) and the BL_ON signals.
The problem can be bad caps (black electrolytics caps), transformers, lamps, bad connection on the board fingers that make contact with lamps.
I would carefully remove the board and clean the contacts pads real well on the inverter board fingers, also look real close at all the sockets where the board fingers are plugged into, see if there is any sign of heat (plastic housing has brownish color).
Can I also see the whole pictures of the inverter board?

[selldoor]

Re: phillips lcd keeps blowing fuse

I am off to bed he has posted pics of the inverter board but has had to split into 4 in post92

There is one white fuse that I can see in pic 1 That should be tested.

The inverters are HS482 TM10BS I cant see any but the tm series seem to have the secondaries along one side - see pic.
Meter on ohms 2000 test S1>S2 and S3>S4 for each transformer and post results.
There are quite a lot of Mosfets (Might be 50N04 s )on the board - Q designation and they should be tested also.

[budm]

Re: phillips lcd keeps blowing fuse

I saw those pictures in post 92, but I can figure it out a little better if i get to see the whole board also, I can see on small current sensing transformer on the board.

[MisterD]

Re: phillips lcd keeps blowing fuse

As I posted in Post # 93, The Inverter Board has some mounting screws missing as I can see in the picture, these circuit boards need all the screws in place and tightened down to make a ground connection, please answer my question, did you install all of these screws and tighten them down? did you make sure every circuit board has all the screws and that they are all tightened down? please reply back to let us know. Thanks.

[TimT]

Re: phillips lcd keeps blowing fuse

MisterD When testing all boards are bolted back down. selldoor the SMF near connector is a 10A fuse I tested it right at 10v. but ill need to recheck the rating. I cant remember the correct voltage but 10v is close.
pulled and cleaned inverter but no luck. as far as i know nothing has been replace on this board. power board is " new " from Encompass parts. budm no brownish color at inverter contacts looked clean.

[budm]

Re: phillips lcd keeps blowing fuse

That white fuse is fed by the 24V power supply, and you are reading 10V, that does not sound right to me. You can see that the fuse is connected to those red wires for the 24v feeding.