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Louie
Louie, Technician
Category: TV
Satisfied Customers: 11433
Experience:  25+ yrs. experience in the field and 5+ yrs. online, down to component level.
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I have a model ELEFT406 Element 40" TV purchased from Target

Customer Question

I have a model ELEFT406 Element 40" TV purchased from Target about 3 years ago. The backlight appears to be dead. Already removed the plastic backcover. I am unable to identify the backlight driver board. Other cards now visible include AC/DC Power supply, main tuner card, FCR board (whatever that is), and what looks like a digital board that feeds the LED panel. There is a metal panel between these cards and the panel. I suspect the backlight driver board is inside the metal panel. Am I correct?
Submitted: 7 months ago.
Category: TV
Expert:  Pete replied 7 months ago.
Hi Dale
Customer: replied 7 months ago.
Where is the answer?
Customer: replied 7 months ago.
I have a model ELEFT406 Element 40" TV purchased from Target about 3 years ago. The back light appears to be dead. Already removed the plastic back cover. Steel baclk cover is visible with ~4 cards. I am unable to identify the back light driver board. Suspect it is inside the steel cover for EMI filtering. Other cards visible include AC/DC Power supply, main tuner card, FCR board, and what looks like a digital board that feeds the LED panel. I suspect the back light driver board is inside the metal panel. Am I correct? Where is the back light board located and how can I debug it?
Customer: replied 7 months ago.
I just added a picture of the TV with the cover off.
Expert:  Louie replied 6 months ago.
Hi Dale and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, the "...backlight driver board...." is the LED Driver and is an integral part of the power supply board; where the AC power cord comes in. The LED backlight strips are powered through the 4 connectors of red and black wires.This combo power supply/LED Driver would have a Part Number of something like CVB42001 depending on version/revision.Based on operation, brightness level and other settings, the output voltage from these connectors would be between 56 and 80 Volts powering each of the 4 LED strips.In some instances, a failed single LED strip can cause the LED Driver circuit to kick in auto-protect mode.
Customer: replied 6 months ago.
See TV drawing I just attached.12V to main RF card is good at CON6.Power on/off LEDS seem to work okPower card has 4 sets of wires in top right corner.
Thee wires plug into sockets mounted to a small daughter board CVB32001-3.
I assume these wires are for the LED back Lights.
Wire are connected by 2 pin plugs to 4 sets of sockets.3 Big caps are next to connectors. I measure 31V across each cap.
But connectors for wire pairs seem to have a problem.Voltage to from each red wire pin to ground are not the same.
Two sets of plugs on right side have 80V (at red wire pin) to ground.
Two sets of plugs on left side have zero volts (at red wire pin) to ground.With power off checked ohms from each black wire to ground.Right side 2 pairs: Black wire pcb pins to ground = open (high ohms)
Left side 2 pairs: Black wire pcb pins to ground = short (low ohms) to ground.Power supply card says CVB42001
Expert:  Louie replied 6 months ago.
Please repeat the voltage measurements of the 4 connectors with the red & black wires to the LED strips removed.
Customer: replied 6 months ago.
Put the boards back together. Took voltage readings again. Ground of DMM to chassis ground.
See picture I am about to upload.
85V
85V
dead (zero)
dead (zero)Sockets that read zero also have dead short from associated Black pin to ground.Socket with 85V do NOT have dead short from black pin to ground.3 pins per socket
1 = Red
2 = empty
3= BlackI think power board is dead. You agree?
Expert:  Louie replied 6 months ago.
Based on the absence of voltages and the shorted readings, then yes; the LED driver/power supply board would be faulty thus needing replacement.
Customer: replied 6 months ago.
Received replacement board today. Same voltages measured as my original suspected bad board. I suspect this is a common problem. Can you send/sell me a schematic for the power board?
Customer: replied 6 months ago.
Where can I buy a known good new board?
Expert:  Louie replied 6 months ago.
Have you tried inquiring from ShopJimmy?