Samsung UN32EH5000FXZA, No Backlight

[johnboy1313]

Re: Samsung UN32EH5000FXZA, No Backlight

The old PSU was outputting way more than the new one. I Would guess that's why six of the 24 LEDs were blown. I didn't want to risk it.

[budm]

Re: Samsung UN32EH5000FXZA, No Backlight

That is great news, now for future reference, what is the output voltage you get with the new board?

[tom66]

Re: Samsung UN32EH5000FXZA, No Backlight

Could the higher voltage be due to the old PSU driving an open circuit LED array?

[ArcticMinibike]

Re: Samsung UN32EH5000FXZA, No Backlight

The old PSU was outputting way more than the new one. I Would guess that's why six of the 24 LEDs were blown. I didn't want to risk it.

I have this EXACT same problem. Did you resolve the problem? How? What voltage did you end up getting at each of the 4 pins, assuming you replaced the power supply board. What voltage did you get at each light strip.

The TV was never worked on, I am the original owner. There are only 2 light strips and no jumper between. That is the factory config. I noticed this was questioned earlier in this thread.

My old power supply was producing between 170-180V at D1+ and D2+. D1- and D2- were both 0V. Voltage input to the light strip connected to D1+ and D2+ was also 170V. Voltage to the second strip fed from D1- and D2- was 0.

I purchased a refurbed power supply board from ShopJimmy and I get 149V at D1+, the 3 other pins are all 0V when simply connecting power to the board with no connection to the main board. If I connect the main board and turn on the unit, everything stays the same but D2- changes to 1.3V. They say the board was tested and refusing to replace it. How can this be a good board with 0V being sent to one of the light strips?

[budm]

Re: Samsung UN32EH5000FXZA, No Backlight

It is the current through the LED you have to worry about, the output from the boost converter will be drop across the LED string AND the PWM controlled MOSFET AND the current sensing resistor to maintain constant current through the LED string, if too much current flowing it will trip the protection circuit (the LED driver IC monitor the Vdrops on the current sensing resistor), he is the one that controls how much current will flow through the LED stings, not all the Voltage at the output of the boost converter appear across the LED string.

[budm]

Re: Samsung UN32EH5000FXZA, No Backlight

I have this EXACT same problem. Did you resolve the problem? How? What voltage did you end up getting at each of the 4 pins, assuming you replaced the power supply board. What voltage did you get at each light strip.

The TV was never worked on, I am the original owner. There are only 2 light strips and no jumper between. That is the factory config. I noticed this was questioned earlier in this thread.

My old power supply was producing between 170-180V at D1+ and D2+. D1- and D2- were both 0V. Voltage input to the light strip connected to D1+ and D2+ was also 170V. Voltage to the second strip fed from D1- and D2- was 0.

I purchased a refurbed power supply board from ShopJimmy and I get 149V at D1+, the 3 other pins are all 0V when simply connecting power to the board with no connection to the main board. If I connect the main board and turn on the unit, everything stays the same but D2- changes to 1.3V. They say the board was tested and refusing to replace it. How can this be a good board with 0V being sent to one of the light strips?

Something does not make sense here, D1+ and D2+ are directly connected together (CNL802) as you can see here:
https://www.badcaps.net/forum/attach...4&d=1423004050

So I cannot see how you get this:'I get 149V at D1+, the 3 other pins are all 0V when simply connecting power to the board'

Is your board the same as OP?

[ArcticMinibike]

Re: Samsung UN32EH5000FXZA, No Backlight

My old power supply was producing between 170-180V at D1+ and D2+. D1- and D2- were both 0V.

CORRECTION: I mixed up the new and old PS. The NEW PS produced 170V - 180V on pins 1 and 2, just as the original author of this thread found on his PS.

Here is the interesting part. I have the exact same TV he had, but mine had a different power supply in it, and I know it has never been worked on. I question whether the TV he found ALREADY had the power supply board replaced with the wrong one before he got it.

I purchased my PS at ShopJimmy. My original board number was BN-4400665A and it has the 2 large caps arranged inline. They were out of stock but they said there was an alternate equivalent power supply, BN-4400493A. It has the large caps side by side.

I figured all was fine because ShopJimmy should know what they're talking about and are reputable. HOWEVER, when I compared the 2 boards, I noticed a big difference. The CNL 802 connector that leads to the 2 light strips seems to be arranged differently. From what I can tell, the way the leads are arranged in the connector, this replacement board can't be used with the existing light wiring harness without rearranging the order of the wires in the connector.

My TV came with a BN44-00665A power supply. The 802 connector on that has the following arrangement from pin 1 to 5, left to right: D+, S-, N, S+, D-. I'm no genius but this appears to me that pins 1 and 4 are hot (or should be if the PS was working).

On the NEW "equivalent" power supply they sent me (BN44-00493A), the CNL 802 pin arrangement is from pin 1-5, left to right: D1+, D1+, N, D1-, D1-. Pins 1 and 2 are hot when I measure them against ground.

Interesting that in the pictures submitted by the originator of this thread, he too has the 493 board with the +,+,N,-,- pin config, but you can see his wiring is 2 side by side pairs of gray and black, just like mine. Each pair of gray and black wires leads to a light strip. Pin 1 (gray wire) goes to + on light strip #1, Pin 2 (black wire with white stripe) goes to - on light strip #1. Likewise, the gray wire on pin 4 goes to + on light strip #2 and the black wire on pin 5 goes to - on light strip #2.

If you look at the fast track guide attached previously in this thread, you'll see a picture of the wiring connected to this BN44-00493 board. Pins 1 and 2 are blue wire, Pins 4 and 5 are black wire. That seems to suggest the blues are both positive and blacks are both negative (+ + N - -), unlike the alternating gray and black on my wiring harness (+ - N + -) and the one shown earlier in this thread on his TV.

Pictures of the 2 boards and my wiring harness are attached.

BTW, ShopJimmy sent me a second BN44-00493A board when I questioned if the one they originally sent me was faulty. It reads exactly the same as the first one they sent me. Those readings to come in a follow up response. I'm sure the board is good, maybe the wrong one, but it is good.

[ArcticMinibike]

Re: Samsung UN32EH5000FXZA, No Backlight

[QUOTE=budm;619352]Something does not make sense here, D1+ and D2+ are directly connected together (CNL802) QUOTE]

Refer to my previous post that notes the differences between the 2 different but supposedly interchangeable power supplies. Perhaps what ShopJimmy means by "Substitute Part" is that it will function as soon as you chop up and rewire your 802 wiring harness.

See how different the traces are on the 493 board from the 665 board. As you pointed out, D1+ and D2+ share a common pad, as do both D- pins on pins 4 and 5.

On the original PS board (665), it's hard to tell what they connect to, but it seems clear pins 1 and 2 are not tied together, nor are pins 4 and 5, as they are on the 493 board.

I can certainly post full pics of the boards if that helps with the comparison. Test voltage readings to follow.

[ArcticMinibike]

Re: Samsung UN32EH5000FXZA, No Backlight

I installed the supposedly compatible board and connected power to it. When I check the voltage, I get 170-180V on pins 1 and 2, 0V on pins 4 and 5 when measuring to ground on each pin individually. That's with the PS disconnected from the main board. When I connect it to the main board and the TV is in standby, the voltage on pins 1 and 2 drops to 95V. When I turn on the TV, The voltage on pins 1 and 2 returns to between 170V and 180V (it cycles up and down between those 2 values). This is a known good power supply, but again, not identical to my original. They (ShopJimmy.com) just claim it to be a compatible replacement, or "substitute part" as they call it.

It seems clear that their claim that the BN44-00493A being compatible is at least partially false. It seems at a minimum that I would have to rearrange the pins on my connector to get the correct voltage and polarities to each pair. To experiment, I did just that. I cut and reconfigured my light wires so that pair 1, leading to the top light strip connects to pins 1 and 4 (+ and - respectively). The second pair, leading to the bottom light strip, now goes to pins 2 and 5 on the new board.

When the TV is on with the screen connected, I now get about 21 volts at each light strip. Some of the lights light up, which is further than I've gotten before, but the voltage seems too low to me.
The top strip has only 6 or 7 lights on (out of 12), and they are very dim. The bottom strip has only 1 light out and the other 11 are much brighter, but nothing close to operating brightness.

Obviously it would be best if ShopJimmy had not claimed this board to be a direct replacement and if possible, I hope to get the right one from them. At a minimum, they need to confirm that reconfiguring the pinouts on the 802 light connector will allow this board to work.

Assuming that this is a compatible board and my adjustments to the pinouts were correct, my questions at this point are...

1. Why the seemingly low voltage at each light strip?

2. Why are the lights on the strip with more burned out lights dimmer, even though it's receiving the same input voltage as the brighter strip. Although I've done cap replacements and built guitar pedal kits, my knowledge ends at following directions and very basic electronics knowledge.

3. What are the chances that I need to replace the main board to resolve my issues, since they are interconnected. Would a faulty main board be causing the output to the lights to be too low?

4. Are these 2 boards really interchangeable and I just don't know what I'm looking at? Highly likely, lol!

[ArcticMinibike]

Re: Samsung UN32EH5000FXZA, No Backlight

Original BN44-00665A PS

[ArcticMinibike]

Re: Samsung UN32EH5000FXZA, No Backlight

"Substitute Part" PS from ShopJimmy BN44-00493A

[ArcticMinibike]

Re: Samsung UN32EH5000FXZA, No Backlight

The sad part is that this "Free" TV from my father-in-law has so far cost me $38 and about 8 hours of head scratching and stress. I could just go buy the new equivalent Samsung 32" for $180...but it's hard to let go of a challenge when I'm this far in.

[budm]

Re: Samsung UN32EH5000FXZA, No Backlight

'BN44-00665A' Do pin 1 and pin 2 connected together, same for pin 4 and pin are also connected together on that LED connector CNL802?

Did you open up the panel to check for bad LEDs like OP did and see how many LED strips are in your panel?
Per the fast track when the Loads are present, you should have 110VDC constant but if the load is not present, then it can go very high Voltage but I do not expect 170VDC with no load. For you to have 170V, it means you have open LED/LEDs on the LED strips.

[ArcticMinibike]

Re: Samsung UN32EH5000FXZA, No Backlight

'BN44-00665A' Do pin 1 and pin 2 connected together, same for pin 4 and pin are also connected together on that LED connector CNL802?

Did you open up the panel to check for bad LEDs like OP did and see how many LED strips are in your panel?
Per the fast track when the Loads are present, you should have 110VDC constant but if the load is not present, then it can go very high Voltage but I do not expect 170VDC with no load. For you to have 170V, it means you have open LED/LEDs on the LED strips.

On the 665 board, pins 2 and 4 connect. I can't easily see it on the trace like on the 493 board but a continuity check with the meter says they do. Pins 1 and 5 are independent of each other and any of the other pins. In other words, pin 1 is unique, pins 2 and 4 are tied, and pin 5 is unique. That's very different from the 493 where 1 and 2 are tied together and 4 and 5 are tied together.

I have opened the panel. There are 2 light strips. on the original 665 board, pins 1 and 2 went to the first light strip (+ and - respectively). Pins 4 and 5 went to the second light strip, (+ and - respectively). As Johnboy described, there are open connectors at the end of each light strip but there is no jumper between the 2 strips. Each is an independent 12 light strip. That is guaranteed to be the way it came from the factory. My father in law used it for years and it was working fine, then one day the lights went out. He then handed it to me.

When I send 20 volts to the first strip, about half of the lights glow very dimly. The ones that glow do so with equal intensity. The rest just don't come on. When the lights are powered off, there is no visual difference between the working lights and those that are out (no black or brown spots).

When I send 20 volts to the second strip, 11 of the 12 lights glow. One is completely out. The ones that glow do so in a much brighter way than the working ones on the first strip.

At a minimum, it's clear that the light strips need to be replaced. Finding them is tough. SJ does not have them in stock and I haven't been able to locate an exact match anywhere else.

It also seems that there is no possible way this 493 PS board can be an acceptable substitute for the 665 board without modifying the wiring harness. Even then, I question if it's possible.

I really wish Johnboy would reply and let us know the outcome. He said he got strips and a PS board from a TV with a broken screen. What I'd like to know is if that fixed his problem, and which PS did he end up with, a 665 or 493.

[budm]

Re: Samsung UN32EH5000FXZA, No Backlight

'I have opened the panel. There are 2 light strips. on the original 665 board, pins 1 and 2 went to the first light strip (+ and - respectively). Pins 4 and 5 went to the second light strip, (+ and - respectively).' That is not the same as the OP board *-493.
Your strips are connected in series.
So it is a matter of getting the new LED strip. You 665 power supply/LED driver board is OK.

[ArcticMinibike]

Re: Samsung UN32EH5000FXZA, No Backlight

Per the fast track when the Loads are present, you should have 110VDC constant but if the load is not present, then it can go very high Voltage but I do not expect 170VDC with no load. For you to have 170V, it means you have open LED/LEDs on the LED strips.

I was seeing the 170 VDC on the 493 board when checking the pins on the PS with no LED's attached. that was on pin 1 to ground and 2 to ground (chassis). That value cycles up and down from around 170 to 180 VDC, just as Johnboy reported on his PS.

I put the original (potentially bad) 665 power supply back in to take some readings. In standby, I get 146VDC on pin 1, 0 on pins 2 and 4, and 128VDC on pin 5. The lights are not connected. If I turn on the TV, those voltages change. Pin 1 becomes 157VDC, pin 2 and 4 remain 0, and pin 5 becomes 1.4VDC.

The lights remain completely out with my original old power supply, however, about 2 or 3 seconds after I power it on, the lights give a quick blink. I was never able to see that before since the strips were enclosed in the panel. Seems like I read of this behavior somewhere, whether it was normal, I don't recall. I was taking some voltage readings and found that If I put one probe on one of the terminals on light strip 1, and the other probe on one of the terminals on light strip 2, they would come on and stay on until I removed the meter probe. They glowed dimly, exactly like I was able to force by sending 20 volts to each with the other power supply.

[budm]

Re: Samsung UN32EH5000FXZA, No Backlight

'I was taking some voltage readings and found that If I put one probe on one of the terminals on light strip 1, and the other probe on one of the terminals on light strip 2, they would come on and stay on until I removed the meter probe. They glowed dimly, exactly like I was able to force by sending 20 volts to each with the other power supply.' That sounds like you have bad connections. 12 LED x 3V = 36VDC per strip, so 20V is not really enough, but always use resistor to limit current or use constant current power supply, if you have LEDS that are shorted out then you can damage the good LED if you test the strip without current limiting.

[ArcticMinibike]

Re: Samsung UN32EH5000FXZA, No Backlight

'I have opened the panel. There are 2 light strips. on the original 665 board, pins 1 and 2 went to the first light strip (+ and - respectively). Pins 4 and 5 went to the second light strip, (+ and - respectively).' That is not the same as the OP board *-493.
Your strips are connected in series.
So it is a matter of getting the new LED strip. You 665 power supply/LED driver board is OK.

How do I know for sure my original 665 PS/driver board is OK? I always assumed something had to go wrong on the board to damage the light strips. Is that wrong to assume? Do lights just go bad on their own? I thought LED's should last much longer than whatever hours are on this TV.

I know I need new lights for sure. The tough part is finding them. SJ doesn't have them in stock and I haven't found them anywhere else.

My biggest concern is that I find them, plug them into my original 665 board, and it damages them. Is it safer to replace the 665 board as well?


BTW, you have been a BIG help.


The more this all starts to fit, the more I think I know what was wrong with the TV that Johnboy got that started this thread. I bet the lights went out in that TV. The previous owner ordered the "substitute" PS, It didn't work because it was not compatible with the light harness. Then it ended up in Johnboy's hands. His photos clearly show the same "665 style" light wiring harness but also that 493 PS substitute.

[budm]

Re: Samsung UN32EH5000FXZA, No Backlight

At this point I have no way to tell what the no load Voltage for feeding the LED strips should be, is has to drive 24 LEDs x 3V = 72V + may be 35~50V for the Vdrops on the PWM Controlled MOSFET.
You are getting 145~155V so it does look high.
But what reaaly damage the LED is the over current, so as long as the drive circuit can maintain and not allwo the current to go over the limit of the LED then it will be OK. To find out you will need to measure the current through the LED strings.

[ArcticMinibike]

Re: Samsung UN32EH5000FXZA, No Backlight

Would you agree that the 493 power supply is NOT a valid substitute? I think I have justification to go back to ShopJimmy and ask for my money back. What do you think?