Samsung UN46D6400UFXZA Version H302 tv has sound but no picture. Screen lights up initially with some horizontal lines then it just lights up (backlights on) but no picture.

Thanks Larry. I replaced the tcon and the main board but that did not correct the problem. Could the problem be with the LED drivers that are on the Pwr Sup board (BN44-00427B)? This PS board is out of stock at ShopJimmy.com so I need a reliable source to purchase if you know of one. Appreciate your help. Thanks Larry. I replaced the tcon and the main board but that did not correct the problem. Could the problem be with the LED drivers that are on the Pwr Sup board (BN44-00427B)? This PS board is out of stock at ShopJimmy.com so I need a reliable source to purchase if you know of one. Appreciate your help.

Sorry about missing the first part of the question of you changing the Tcon. As long as the LED's are lit up you should have the correct voltage to the LED's, you can test it if you want, I believe they run around 100 VDC on that set, I don't have a service manual in front of me to verify that though. If you have changed the main and Tcon there really isn't anything left but the power board or the panel. I would check the power supply voltages and see if they are all correct instead of ordering another board that doesn't fix it, if they are all correct then unfortunately you have a bad panel or cables and those seldom give issues Sorry about missing the first part of the question of you changing the Tcon. As long as the LED's are lit up you should have the correct voltage to the LED's, you can test it if you want, I believe they run around 100 VDC on that set, I don't have a service manual in front of me to verify that though. If you have changed the main and Tcon there really isn't anything left but the power board or the panel. I would check the power supply voltages and see if they are all correct instead of ordering another board that doesn't fix it, if they are all correct then unfortunately you have a bad panel or cables and those seldom give issues

Measured voltage at output caps C9817, C9831, C9818 and C9832 as 138.5 vdc, 137.7, 138.0 and 137.3 respectively.
Also measured dc voltage at the two connectors to the Panel CNL801 and CNL801A as follows:
CNL801A
Pin 12 130.1 and Pin 1 136.8 (White wires)
Pin 15 74,2 and Pin 4 74.6 (White wires)
Pin 17 136.7 and Pin 6 135.9 (White wires)
Pin 20 12.8 and Pin 9 12.9 (Black wires)
Pin 22 2.2 and Pin 11 2.2 (Blue wires)


CNL801
Pin 10 135.6 and Pin 1 136.3 (Blue wires)
Pin 13 74.0 and Pin 4 74.4 (White wires)
Pin 15 136,7 and Pin 6 135.6 (White wires)
Pin 18 74.4 and Pin 9 74.0 (White wires)

Based on this do you think it is the power supply or is it the panel? Is it safe to assume if it is the panel that it would be cost prohibitive to replace? Thanks. Measured voltage at output caps C9817, C9831, C9818 and C9832 as 138.5 vdc, 137.7, 138.0 and 137.3 respectively. Also measured dc voltage at the two connectors to the Panel CNL801 and CNL801A as follows: CNL801A Pin 12 130.1 and Pin 1 136.8 (White wires) Pin 15 74,2 and Pin 4 74.6 (White wires) Pin 17 136.7 and Pin 6 135.9 (White wires) Pin 20 12.8 and Pin 9 12.9 (Black wires) Pin 22 2.2 and Pin 11 2.2 (Blue wires) CNL801 Pin 10 135.6 and Pin 1 136.3 (Blue wires) Pin 13 74.0 and Pin 4 74.4 (White wires) Pin 15 136,7 and Pin 6 135.6 (White wires) Pin 18 74.4 and Pin 9 74.0 (White wires) Based on this do you think it is the power supply or is it the panel? Is it safe to assume if it is the panel that it would be cost prohibitive to replace? Thanks.

Something isn't right here but I don't have a schematic for this set so not sure what it is...did you use the metal frame as the ground when measuring the various voltages at connector CNL801 and 801A?...you should have a 5 and a 12 volt line that feeds the main board along with possibly a 3.6 volt supply and I know they are working as you have sound, also you shouldn't see 135 volts anywhere, with the LED's on it should be around 100...makes me think you wern't at frame ground or a floating ground when you took the readings Something isn't right here but I don't have a schematic for this set so not sure what it is...did you use the metal frame as the ground when measuring the various voltages at connector CNL801 and 801A?...you should have a 5 and a 12 volt line that feeds the main board along with possibly a 3.6 volt supply and I know they are working as you have sound, also you shouldn't see 135 volts anywhere, with the LED's on it should be around 100...makes me think you wern't at frame ground or a floating ground when you took the readings

Larry, You are correct that on the connector to the main board, which is CNM802, I do have 5.3, 12.77 and 3.75 vdc. I then rechecked the other voltages on the other 2 connectors that go to the LED panel making sure I was on either the chassis or the ground lug on the Pwr Sup board. They are as I previously identified and remain solid at ~138 vdc and as per my prior comments. Can you check a schematic on this Pwr Sup Board, PN# BN44-00427B Rev 11 and let me know if this is correct and if not has the portion of pwr Sup board that pwrs the LEDs failed? Do you think the LED panel has failed and if so are costs prohibitive or not worth replacing. Thanks again for your help on this. The set is not that old (coming up on 4 yrs) so that why I am asking. Larry, You are correct that on the connector to the main board, which is CNM802, I do have 5.3, 12.77 and 3.75 vdc. I then rechecked the other voltages on the other 2 connectors that go to the LED panel making sure I was on either the chassis or the ground lug on the Pwr Sup board. They are as I previously identified and remain solid at ~138 vdc and as per my prior comments. Can you check a schematic on this Pwr Sup Board, PN# BN44-00427B Rev 11 and let me know if this is correct and if not has the portion of pwr Sup board that pwrs the LEDs failed? Do you think the LED panel has failed and if so are costs prohibitive or not worth replacing. Thanks again for your help on this. The set is not that old (coming up on 4 yrs) so that why I am asking.

138 volts on the LED is to high, basically what is happening is the signal that turns on the LED's isn't there, that voltage drops to about 100 when the lights are on, with no load it will be in the 130s..Unfortunately I don't have a manual for this set and its not one that can be found online (or I didn't find it) it can be downloaded from manuals online I'm sure as they have about every manual there is but its somewhat costly around 20 bucks for most of them. Try one other thing, if you unplug the power going to the main board but leave the connector hooked to the LED's if the lamps are good you should see the lamps light up. That will tell if the lamps are ok. 138 volts on the LED is to high, basically what is happening is the signal that turns on the LED's isn't there, that voltage drops to about 100 when the lights are on, with no load it will be in the 130s..Unfortunately I don't have a manual for this set and its not one that can be found online (or I didn't find it) it can be downloaded from manuals online I'm sure as they have about every manual there is but its somewhat costly around 20 bucks for most of them. Try one other thing, if you unplug the power going to the main board but leave the connector hooked to the LED's if the lamps are good you should see the lamps light up. That will tell if the lamps are ok.

OK Larry, I disconnected the power to the main board and then powered up the TV. There are no backlights on so I checked the voltages on the the Pwr Sup board (BN44-00427B) connectors CNL801A and CNL801B and now see the following.

There are no LED (backlight) illuminated.
So I measured the voltage at output caps C9817, C9831, C9818 and C9832 which dropped from 138 vdc when the power to the main board was connected to 84 vdc after the power connection to the main board was removed.

I also re-measured the dc voltage at the two connectors CNL801A and CNL801s on the power supply board (BN44-00427B) that run to the Panel as follows:

CNL801A
Pin 12 dropped from 130.1 to 32.3 and Pin 1 dropped from 136.8 to 32.3 (White wires)
Pin 15 dropped from 74.2 to 0 and Pin 4 dropped from 74.6 to 0 (White wires)
Pin 17 dropped from 136.7 to 32.3 and Pin 6 dropped from 135.9 to 32.3 (White wires)
Pin 20 dropped from 12.8 to 0 and Pin 9 dropped from 12.9 to 0 (Black wires)
Pin 22 remained at 2.2 and Pin 11 remained at 2.2 (Blue wires) (No change)


CNL801B
Pin 10 dropped from 135.6 to 84 and Pin 1 dropped from 136.3 to 84 (Blue wires)
Pin 13 dropped from 74.0 to 32.6 and Pin 4 dropped from 74.4 to 32.6 (White wires)
Pin 15 dropped from 136.7 to 84 and Pin 6 dropped from 135.6 to 84 (White wires)
Pin 18 dropped from 74.4 to 32.3 and Pin 9 dropped from 74.0 to 32.3 (White wires)

I assume when you say "see if the lamps are good" you are talking about the LEDs? Is this different than the back lighting LEDs which do come on when all cables are installed?

Based on the above information do you think it is the power supply or is it the panel? If is the panel would it be cost prohibitive to purchase a replacement? Thanks for your help on this. OK Larry, I disconnected the power to the main board and then powered up the TV. There are no backlights on so I checked the voltages on the the Pwr Sup board (BN44-00427B) connectors CNL801A and CNL801B and now see the following. There are no LED (backlight) illuminated. So I measured the voltage at output caps C9817, C9831, C9818 and C9832 which dropped from 138 vdc when the power to the main board was connected to 84 vdc after the power connection to the main board was removed. I also re-measured the dc voltage at the two connectors CNL801A and CNL801s on the power supply board (BN44-00427B) that run to the Panel as follows: CNL801A Pin 12 dropped from 130.1 to 32.3 and Pin 1 dropped from 136.8 to 32.3 (White wires) Pin 15 dropped from 74.2 to 0 and Pin 4 dropped from 74.6 to 0 (White wires) Pin 17 dropped from 136.7 to 32.3 and Pin 6 dropped from 135.9 to 32.3 (White wires) Pin 20 dropped from 12.8 to 0 and Pin 9 dropped from 12.9 to 0 (Black wires) Pin 22 remained at 2.2 and Pin 11 remained at 2.2 (Blue wires) (No change) CNL801B Pin 10 dropped from 135.6 to 84 and Pin 1 dropped from 136.3 to 84 (Blue wires) Pin 13 dropped from 74.0 to 32.6 and Pin 4 dropped from 74.4 to 32.6 (White wires) Pin 15 dropped from 136.7 to 84 and Pin 6 dropped from 135.6 to 84 (White wires) Pin 18 dropped from 74.4 to 32.3 and Pin 9 dropped from 74.0 to 32.3 (White wires) I assume when you say "see if the lamps are good" you are talking about the LEDs? Is this different than the back lighting LEDs which do come on when all cables are installed? Based on the above information do you think it is the power supply or is it the panel? If is the panel would it be cost prohibitive to purchase a replacement? Thanks for your help on this.

Its looking like you have a bad panel and yes those cost more than the set did new, Ive never replaced one my self but Ive heard they can run up to a grand way more than the set cost new Its looking like you have a bad panel and yes those cost more than the set did new, Ive never replaced one my self but Ive heard they can run up to a grand way more than the set cost new