Samsung ue32f4570ss with power supply BN44-00604F

[cesarius]

Hello there,

I hope I get some help repairing the tv for my Neighbour.

The symptoms: sound working, no image. My Neighbour told me that he left the TV on for more then 3 hours like this and suddenly the Image came back (So I guess LED strips are ok). After shutting the tv down and restarting the Image was gone again with remaining sound.

What I've checked: On the Power supply board the Connector CM865(the left one on the first Image) both volatages 13 and 5,3V are available. Same on the caps. In addition I checked all solder joints on the board and they seem to be all ok. I resoldered most of them anyway without luck. Visually all Caps are ok and nothing is blown.
I've tried to heat up a little bit the Power board with hair dryer but nothing changed.

I found the similar board on this thread with blown resistors here but in my case both resistors are ok (2 Ohm)

Is it possible that the caps are bad? Any other advice to check?
Thanks in advance.

[dick_barton]

Re: Samsung ue32f4570ss with power supply BN44-00604F

Have you checked with a bright light shone on the screen at an angle to see if you have a picture. It could be the backlights are off.

Can you give the voltages on the connector shown in the red box. The pin names are shown in the second red box.

[cesarius]

Re: Samsung ue32f4570ss with power supply BN44-00604F

You're right, the picture is completly there but the Backlight is off.

Here are all Voltages:
Connector Description Measured Voltage
1...............B13V...............13V
2...............PWM DIM.........1V
3...............B13V...............13V
4...............Eco ONOFF.......0V
5...............Vamp...............13V
6...............BLU ONOFF.......4,8V
7...............Vamp...............13V
8...............GND
9...............GND
10...............GND
11...............B5V...............5,3V
12...............A5V...............5,2V
13...............B5V...............5,3V
14...............PSONOFF........3,3V

[dick_barton]

Re: Samsung ue32f4570ss with power supply BN44-00604F

I'm not sure what Eco OnOff is but all the other voltages appear to be good.
What is the number written on top of the IC in the red box?

[cesarius]

Re: Samsung ue32f4570ss with power supply BN44-00604F

In addition I've checked the voltages on the other connector that should be 146V but there is no voltage at all there.
I am a little bit confused though about the pinout of that connector. On the Board it says Pin 1 and 2 Not connected, 3 and 4 are 4- and 4+ but as one can see on pin 4 there is no cable. Pin 4 and 6 are not soldered together.

[cesarius]

Re: Samsung ue32f4570ss with power supply BN44-00604F

The upper Number is Z1948A the second is Bc13h6 or may be B013h6 but I guess that is a date code.

Found this schematics on a polish website but no data sheet.

[dick_barton]

Re: Samsung ue32f4570ss with power supply BN44-00604F

The set appears to have an Eco Solution setting which can dim your picture or switch the picture off. I think the 0V you are reading at Eco ONOFF pin may be switching the picture off.

[cesarius]

Re: Samsung ue32f4570ss with power supply BN44-00604F

So do you think there is no faulty hardware?

[dick_barton]

Re: Samsung ue32f4570ss with power supply BN44-00604F

Looks like the IC is an AOZ1948A led driver. Can you carefully measure the DC voltages on the pins.
https://www.scribd.com/document/359977160/AOZ1948AI

[dick_barton]

Re: Samsung ue32f4570ss with power supply BN44-00604F

So do you think there is no faulty hardware?

There is a fault somewhere so it's a matter of pinning it down.

[cesarius]

Re: Samsung ue32f4570ss with power supply BN44-00604F

Thank you for the data sheet. I will try to measure, it's quite hard cause it's horribly tiny.

BTW. I rechecked the connector. ECO ON/OFF pin is not connected.

[dick_barton]

Re: Samsung ue32f4570ss with power supply BN44-00604F

Then it is starting to look like a probable led fault. Possibly open circuit. Can you measure the voltages on the led connector and note the voltage on each pin as you power up. The voltage may peak and then drop. Repeat for each pin and list in table format like you did in post #3

[cesarius]

Re: Samsung ue32f4570ss with power supply BN44-00604F

There is no voltage peak at all when starting, it all remains at 0V. As I've written in Post #5, I am also a little bit confused about the pinout, the cables do not match the pintout printed on the board. The board tells me there should be 10 cables (+1,-1,+2,-2,+3,-3,+4,-4,IF1,IF2), but there is only 6 cables (3 pairs). So I measured the voltages on the cable pairs (diagonally blue and black, see image on post #5).

I don't know if this is important. But near the LED Driver IC there is component(see picture) that looks like a transistor but it is labeled on the board with D9152 (I guess a diode?) it only shows 47 Ohm on all ends and the diode test shows 082 in both ways.

[dick_barton]

Re: Samsung ue32f4570ss with power supply BN44-00604F

It may be a double diode in a single package but I'm not 100% certain however the data sheet I found was for the BAV70.


https://www.ebay.com/itm/50pcs-BAV70...-/302077530354

[budm]

Re: Samsung ue32f4570ss with power supply BN44-00604F

Can I see straight shot pictures of the whole top and bottom side of the board without so much glare so I can clearly see the driver section?
BTW, inspect and re-solder all the Transformer legs and any device that has through hole rivet.
The Voltage on the +1 pin of the LED connector is where the boosted Voltage if ed to the Anode of the first LED string, the LED strings inside the panel are connected in series to form one large string.
You need to leave the black probe of the meter on the chassis and also leave the red probe on +1 pi and keep them there then turn on the TV to see how high the Voltage jumps up to.

[cesarius]

Re: Samsung ue32f4570ss with power supply BN44-00604F

I will try to exchange the double diode and all caps later and see if it helps.

The Voltage on the +1 pin of the LED connector is where the boosted Voltage if ed to the Anode of the first LED string, the LED strings inside the panel are connected in series to form one large string.
You need to leave the black probe of the meter on the chassis and also leave the red probe on +1 pi and keep them there then turn on the TV to see how high the Voltage jumps up to.

Ok, I thought +1 and -1 is DC-Voltage source 1 aso.
I hope the pictures are better:

EDIT: measured +1 (Pin 12 on connector) against chassis gnd: while in stdby 209v, when starting it raises til 219v and keeps constant.
If the led stripes are bad why did the backlight turned on after a while like I mentioned in my first post? 219V are way to high though as it should be 146V as printed on the board.

[dick_barton]

Re: Samsung ue32f4570ss with power supply BN44-00604F

219V is way too high and means that the leds are not drawing current. Once they draw current the voltage supplying them falls to what is printed on the circuit board which you say is 146V.
The backlights may have switched on as in your first post because one or more of the led's had started to fail but not completely or you may have an intermittent fault on the wiring harness connecting the led strips which is not that uncommon.

[cesarius]

Re: Samsung ue32f4570ss with power supply BN44-00604F

Thanks for the explanation. I will test the backlight LED Stripes. Damn the TV set is only 3~4years old. My own LG TV is hitting the 7th year without any problems. Any suggestion for my Neighbour for a new TV set that have a longer life span then 4 years? Thanks again for the very nice support! Great Forum!

[cesarius]

Re: Samsung ue32f4570ss with power supply BN44-00604F

I disassembled the screen and tested all individual leds. Only one did not light up. I guess that is the fault. Have found a local(!) dealer for a replacement Stripe.

[dick_barton]

Re: Samsung ue32f4570ss with power supply BN44-00604F

Unfortunately many sets are now made to a low price and subsequently appear to have a lower life span.

Turning down the backlights (not brightness) can help to reduce led failures. I also tend to switch my set off at the mains when not in use.

A Panasonic plasma set which I bought about 8 years ago at roughly 3 times the current price of leds sets is still running like new.