Need help to identify "7014x" SOIC-8 LED driver

[ngth82]

Good morning Badcaps!

I'm looking at a Samsung UN46H6201 smart TV from December 2014. 42 of the 44 backlight LEDs were shorted out. I replaced all of them, but the backlights don't turn on (each strip tested OK with my LED tester). I have a feeling it's the backlight driver on the SMPS that is bad.

The power supply board is BN44-00771A. The led driver package is an SOIC-8, but I cant find the datasheet for it. Would someone happen to know where the datasheet is?

The backlight driver (on the back) is labeled:

7014X
1438
K6D

Pin 1
Pin 2
Pin 3 - GND
Pin 4
Pin 5
Pin 6
Pin 7
Pin 8

On the top side, there is an N-FET (TK8A50D) and a diode (SF23G) that has darkened the PCB. I removed them out of circuit to test - the N-FET does not appear to be shorted, nor does the diode. These were correctly identified with my parts tester.

Thank you,
Thomas

[R_J]

Re: Need help to identify "7014x" SOIC-8 LED driver

I have found that the MAP3511 may be SIMILAR, It may not be a direct replacement. Check the voltage on CNL803 pin1 when you first turn on the tv.

[ngth82]

Re: Need help to identify "7014x" SOIC-8 LED driver

@R_J - thanks! I'll have to look at it some more to figure out the other 7 pins this evening. i'll trace it then update the backside image with annotations.

I'll get back to ya!

EDIT: This page seems to show the MAP3511 as a cross reference for the 7014X (though, i'll continue investigating) : http://teleservis.com.ua/shop/index....4&search=7014x

Looks like i can get 5 of them for ~$3.25 from AliExpress. https://www.aliexpress.com/item/4000317720450.html I'll have to add some probe wires and see what's going on.

Thank you,
Thomas

[budm]

Re: Need help to identify "7014x" SOIC-8 LED driver

I have found that the MAP3511 may be SIMILAR, It may not be a direct replacement. Check the voltage on CNL803 pin1 when you first turn on the tv.

+1 on checking Voltages on the LED connectors.

[ngth82]

Re: Need help to identify "7014x" SOIC-8 LED driver

Hi Budm and R_J:

This is what i get on CNL803. All measurements taken relative to the chassis ground.

Pin 1 - M1+ == 233V
Pin 2 - M1- == 206V
Pin 3 - NC
Pin 4 - M2+ == 206V
Pin 5 - M2- == 180V
Pin 6 - NC
Pin 7 - M3+ == 180V
Pin 8 - M3- == 155V
Pin 9 - NC
Pin 10 - M4+ == 155V
Pin 11 - M4- == 233V (?!?)

The backlights are wired with four strips in series.

I double checked the connection on Pin 11 - it is really sitting at 233V.

Diode D9801C (next to the N-channel FET) shows a voltage of 233V on both sides.
The same with the diode - it's 233 volts on both sides as well.

Assuming the MAP3511 is a representative circuit, then that diode could be bad possibly? I'll pull the diode and test it out of circuit.

[ngth82]

Re: Need help to identify "7014x" SOIC-8 LED driver

*Note, in post #1 - I'm re-reading post #1 - I incorrectly stated that I tested the diode out of circuit. It was only the N-FET at that time.

I pulled the diode and tested it. In diode mode, i get +0.6V with the positive lead on the marked (cathode) side, and +0.4v with the positive lead on the anode side. The resistance through the diode is approx 740kOhm with leads in both orientations.

The SF23G appears to be a 2A, 150V diode.

Looks like i have a SB5150 (5A 150V Schottky) in my parts bin.

[ngth82]

Re: Need help to identify "7014x" SOIC-8 LED driver

Yep, it was a bad diode. 10 cent part...

At least i can start reassembling the panel and get most of the stuff off of the floor!

As always, thanks guys!

@Budm - also, i bought more of those 1W LEDs you pointed me to a few weeks ago - $15 for 1K isn't bad. That should last me a good while.

[budm]

Re: Need help to identify "7014x" SOIC-8 LED driver

Samsung uses a lot of that topology for the backlights driver, AOZ1948 also the same topology. That diode seems to fail a lot with bad leakage resistance in that circuit.
Glad you got it fixed.

[ngth82]

Re: Need help to identify "7014x" SOIC-8 LED driver

Good to know for the next time. One more tool in the tool box.

Thanks again!

[ngth82]

Re: Need help to identify "7014x" SOIC-8 LED driver

Well, maybe i spoke too soon.

I turned on the TV for the second time and the backlights were off. I looked closer with the room lights off - the backlights are barely on - biased just enough to see a faint glow on the TV in a dark room. I'm able to barely make out the contents on the display as well. The backlight PWM signal is sitting at 2.5V - this should be plenty bright at that value, but what i see on the screen and through the chassis holes is almost nothing.

The input voltage to the LED connector is sitting at 200 something volts.

I'm able to get the display to come back to full brightness when i change the picture mode to something else (e.g. standard, movie, dynamic, etc).

When i turn the TV off, and back on, the same thing happens.

Interestingly enough, if i disconnect the power cable to the main board, the backlights come on at full brightness - every time. Maybe this is a timing problem with the PWM signal. I can likely just bias the PWM at 2.5V with a resistor divider and call it good.

I'll see about spending additional time on this over the next few days. Firmware update first, then followed by additional debug. At the very least, the LEDs are good now.

Samsungs have been a lot more troubles than what its worth.

[ngth82]

Re: Need help to identify "7014x" SOIC-8 LED driver

I just ended up disconnecting the PWM signal from the main board and biasing it at 2.5V. This appears to work over the last 10 hours that i had the TV on and with several manual power cycles during that time.

The side effect is that the backlights are on prior to the main board/T-Con driving a valid video signal. You see "garbage" on the screen for a brief period of time during the init, then the SmartTV logo appears.

The same is true for powering off - there is some static / "garbage" that you see on the screen when normally the backlight is already off. The SMPS powers off some seconds later.

The unit seems to be good to go. This will replace one of the sets in the house.

I picked this up for $20, and threw $5 of replacement SMT LEDs at it. Not bad.


OP Topic closed. Hopefully this helps someone else down the line.

[xeos]

Re: Need help to identify "7014x" SOIC-8 LED driver

Yep, it was a bad diode. 10 cent part...

I have the same board, with the same toasted looking part, but I haven't tested it. If it's working properly would I be able to tell using a multimeter? My TV's backlight doesn't even turn on, and I'm just assuming it's an issue with the power board.

[xeos]

Re: Need help to identify "7014x" SOIC-8 LED driver

*Note, in post #1 - I'm re-reading post #1 - I incorrectly stated that I tested the diode out of circuit. It was only the N-FET at that time.

I pulled the diode and tested it. In diode mode, i get +0.6V with the positive lead on the marked (cathode) side, and +0.4v with the positive lead on the anode side. The resistance through the diode is approx 740kOhm with leads in both orientations.

The SF23G appears to be a 2A, 150V diode.

Looks like i have a SB5150 (5A 150V Schottky) in my parts bin.

On mine it's a SF28G. I removed it and used an MTESTER circuit identifier to check it's values. The capacitance is 22pF, which is right. But the Uf=548mV, which I can't match to the spec sheet on digikey. What does that refer to, and is it correct?

[xeos]

Re: Need help to identify "7014x" SOIC-8 LED driver

ps using the diode tester on my multimeter it shows the forward voltage (drop) as around .5v, and the reverse as infinite. So it sounds like my diode is fine.