Re: 40" RCA L40FHD41 No Picture + No Audio
no power for testing continuity.
dc for testing the connector.
no power for testing continuity.
dc for testing the connector.
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WHY CAN'T PHILIPS USE PHILLIPS HEAD SCREWS? -
Re: 40" RCA L40FHD41 No Picture + No Audio
Would backlights cause half of the screen to be red/black?
weird that the screen used to be blueComment
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Re: 40" RCA L40FHD41 No Picture + No Audio
The connector has very tiny entrance holes for each individual wire on the connector, so small i can't get my meter probes in to test it...
If i disconnect that connector i can test each pin from the connector but the TV won't be on, which i assume is incorrect for this testing?Comment
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Re: 40" RCA L40FHD41 No Picture + No Audio
nvm that last comment, it is possibleComment
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Re: 40" RCA L40FHD41 No Picture + No Audio
I've tested the connector going from power board to main board, in standby and with power on...
Here are the results attached
looks like an issue with DIM BL_ON pins
low voltage on one of the pins
STANDBY READINGS
pcb mark pin# voltage
________________________
DIM BL_ON 1 0.02v 2 0.0v
GND PW 3 0.0v 4 0.05
+5VSB 5 4.96v 6 4.96v
GND 7 0.00v 8 0.00v
GND+12V 9 0.00v 10 0.09v
+12V 11 0.09v 12 0.09v
GND 13 0.00v 14 0.00v
+12V 15 0.09v 16 0.09v
POWER-ON READINGS
pcb mark pin# voltage
________________________
DIM BL_ON 1 1.66v 2 3.99v
GND PW 3 0.00v 4 2.36v
+5VSB 5 4.97v 6 4.97v
GND 7 0.00v 8 0.00v
GND+12V 9 0.00v 10 11.77v
+12V 11 11.77v 12 11.77v
GND 13 0.00v 14 0.00v
+12V 15 11.77v 16 11.77vLast edited by ajsterr4; 05-26-2017, 10:12 PM.Comment
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Re: 40" RCA L40FHD41 No Picture + No Audio
is the bl_on pin staying at 3.99v when the backlights go out?
the dimming pin is good.
if you have a couple of 1k resistors, you could jump the ps on to see if the backlights stay on.WHY CAN'T PHILIPS USE PHILLIPS HEAD SCREWS?Comment
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Re: 40" RCA L40FHD41 No Picture + No Audio
oh i thought DIM BL_0N was all one thing
i understand... yes it stays at 3.99
I don't have the resistorsComment
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Re: 40" RCA L40FHD41 No Picture + No Audio
so the backlights should stay on then.
if you remove the inverter cover, there will be a couple of caps under the shield. take a look at them for signs of failure.WHY CAN'T PHILIPS USE PHILLIPS HEAD SCREWS?Comment
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Re: 40" RCA L40FHD41 No Picture + No Audio
The backlights come on only on the right side of the tv, where it shows red, then they turn off
but the backlights aren't coming on at all on the left side of the TV
i removed the cover and theres 4 capacitors 350microfarads 35v
all 4 look fine, no bulgeLast edited by ajsterr4; 05-26-2017, 10:42 PM.Comment
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Re: 40" RCA L40FHD41 No Picture + No Audio
So you do have BL-ON and Dimming that means the control signals are fine, but do you have 24VDC at the inverter board and is it staying at 24VDC? If it does then you have problem with either the lamps or the inverter board itself if the backlights do not stay on. Look at the back of the screen in the dark room to see if the backligts are on and staying on or not.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: 40" RCA L40FHD41 No Picture + No Audio
Budm, how do i check for 24VDC at the inverter board?
I did a meter readings on the main connector going from ps board to inverter and the pins that are hot are all at 2.43v
the other pins say VIN, GND, Error out, etc...
The backlights aren't staying on, only one side comes on then for a sec then they shut offLast edited by ajsterr4; 05-26-2017, 10:52 PM.Comment
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Re: 40" RCA L40FHD41 No Picture + No Audio
as for continuity tests
a few of the 8 caps i changed are 1000uF 35v caps:
i got a continuity of 1100 and it kept rising
there are a few 16v caps too, some get ~830, some get ~730 continuityComment
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Re: 40" RCA L40FHD41 No Picture + No Audio
Vin is the 24Vin for the inverter.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: 40" RCA L40FHD41 No Picture + No Audio
pins 1-5 are Vin and they're reading 2.43v precisely when tv is powered onComment
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Re: 40" RCA L40FHD41 No Picture + No Audio
it would need to rise to the 24v or close to, to start lighting the lamps. try measuring it again either from the connector on the ps or the connector on the inverter.WHY CAN'T PHILIPS USE PHILLIPS HEAD SCREWS?Comment
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Re: 40" RCA L40FHD41 No Picture + No Audio
Ok, that was my error; the pins are reading 24.3v when the TV is powered on - no fluctuation in voltageComment
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Re: 40" RCA L40FHD41 No Picture + No Audio
in that case, your ps is good.
now we need to look at your inverter and backlights.
can you get a high res pic of your inverter board.WHY CAN'T PHILIPS USE PHILLIPS HEAD SCREWS?Comment
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Re: 40" RCA L40FHD41 No Picture + No Audio
Ok, i took a series i pics of the board, its long so the pictures are numbered 1-4
if you need better ones i can do so
i know you can't see the tops of the caps on the inverter board, they aren't bulged - i guess that doesn't neccessarily mean they're still good. I can check them out of circuit or in?Attached Filesif you find these attachements useful please consider making a small donation to the site
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Re: 40" RCA L40FHD41 No Picture + No Audio
on the transformers, resistance test the output pins that i have marked out.
no power applied during testing.
these are the output pins that drive each backlight ccfl. you would not put your meter anywhere near these with power applied. very high voltage.
check all of the transformers, top to bottom. the top one will have a different resistance to the others, but we still need to know how it reads. you are looking foe one output that is noticeably different to the others.
p.s. i'm guessing these pics are off of a phone, as they are tiny when i extract them to my desktop.Attached Filesif you find these attachements useful please consider making a small donation to the site
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