(Solved) Samsung ln52b630n1fxza no backlight but has sound and pic


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(Solved) Samsung ln52b630n1fxza no backlight but has sound and pic

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arcsum68
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Aug 19, 2015, 9:16 PM

Post #1 of 27 (5420 views)
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(Solved) Samsung ln52b630n1fxza no backlight but has sound and pic	Can't Post

Hey all, searched but was not able to find anything I felt relevant to the issue, feel free to shoot me a link if you know of something.

As stated I have Samsung ln52b630n1fxza thats not working.

I left the TV sit for probably 6 months after it stopped working, when I went to try to troubleshoot it I could not replicate the problem. I am sure that's relevant somehow. I literally let the thing run for 16 hours and it never once shut down, so I decided to move it into the bedroom. It sat there plugged in for about a month while I was running cables to the bedroom to support it. When I finally go to use it, it would only stay on for maybe 5 minutes (back to the original problem). I suspect that leaving it plugged in is part of the problem. Its now at a point where it almost immediately shuts off.

The TV has no backlight
The TV does have a picture if I shine a flashlight on it
If I remove the cable from the mainboard, the backlights do come on but not immediately and do not stay on.

I assume it's either the mainboard, PSU, or inverters but am not sure how to test further. I would like to just replace one of the components, but I am not sure which one and dont want to just throw money at it.

Can anyone help?
TY in advance.

(This post was edited by arcsum68 on Oct 7, 2015, 5:23 PM)

jts1957
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Aug 19, 2015, 10:19 PM

Post #2 of 27 (5414 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Or da bulbs.

-------------------------
Location: Far, Far Away

(This post was edited by jts1957 on Aug 19, 2015, 10:33 PM)

arcsum68
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Aug 20, 2015, 12:26 AM

Post #3 of 27 (5408 views)
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Re: [jts1957] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

both my Panny plasmas are still kicking, one is a few years older than the LCD. The ST50 is a fantastic set, but newer.

Are bulbs serviceable? Or even worth it?

(This post was edited by arcsum68 on Aug 20, 2015, 12:27 AM)

jts1957
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Aug 20, 2015, 1:00 AM

Post #4 of 27 (5404 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Quote

both my Panny plasmas are still kicking, one is a few years older than the LCD. The ST50 is a fantastic set, but newer.
If I remove the cable from the mainboard, the backlights do come on but not immediately and do not stay on.

What do panny plasmas have to do with this?
Is screen evenly lit top to bottom left to right?

If so ... Inverter board number?

-------------------------
Location: Far, Far Away

(This post was edited by jts1957 on Aug 20, 2015, 1:02 AM)

arcsum68
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Aug 20, 2015, 5:24 AM

Post #5 of 27 (5397 views)
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Re: [jts1957] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Just pointing out how lame it is that this TV has already gone out when I have an older plasma still going strong.

Screen lights evenly when its working, at this point thats only for about 2 seconds at a time.

PSU is Samsung BN44-00267A and has an integrated inverter, additionaly it has Samsung LJ97-02096A

jts1957
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Aug 20, 2015, 8:13 AM

Post #6 of 27 (5394 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Standby LED is lit? Does it play (and finish) its turn on melody? Can OSD/Menus be seen?

Lamps should STAY On with the main to I/P cable unplugged.

What test equipment do you have available to you? Scope?

-------------------------
Location: Far, Far Away

(This post was edited by jts1957 on Aug 21, 2015, 2:29 AM)

arcsum68
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Aug 21, 2015, 1:08 AM

Post #7 of 27 (5364 views)
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Re: [jts1957] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

No scope, but I measured the voltage at the cable going to the mainboard from the PSU.

If I am looking at the connector from the back, where is pin 1 and 2, not sure what the sequence is.

Does it go like this?

7 8
5 6
3 4
1 2

jts1957
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Aug 21, 2015, 2:14 AM

Post #8 of 27 (5360 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Second try:
Standby LED is lit? Does it play (and finish) its turn on melody? Can OSD/Menus be seen?

Lamps should STAY On with the main to I/P cable unplugged.
____________________________________________________________
http://assets.shopjimmy.com/...s/j/sjbn4400267a.jpg

"Even" pins on the inside - "Odd" pins on the outside (the outside being closest to the edge of the PC board). Back probe the harness connector that plugs into CN802.

-------------------------
Location: Far, Far Away

(This post was edited by jts1957 on Aug 21, 2015, 2:29 AM)

arcsum68
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Aug 21, 2015, 2:15 AM

Post #9 of 27 (5359 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Actually it must be like this based on readings and the legend

8 7
5 6
4 3
1 2

Please confirm

arcsum68
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Aug 21, 2015, 3:52 AM

Post #10 of 27 (5350 views)
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Re: [jts1957] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Standby LED is lit? yes
Does it play (and finish) its turn on melody? yes
Can OSD/Menus be seen? not without a flashlight

ty btw, really appreciate the help

(This post was edited by arcsum68 on Aug 21, 2015, 3:53 AM)

arcsum68
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Aug 30, 2015, 10:52 PM

Post #11 of 27 (5261 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

I was just messing with the TV and realized that 1 of the heatsinks (the black one) on the power supply is energized. Is that an indication of a problem with the PSU? It shocks you if you touch it and ground and measures 50v DC.

jts1957
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Aug 30, 2015, 11:37 PM

Post #12 of 27 (5260 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Many heat sinks are NOT connected to chassis ground.

Isolation transformers are rarely used nowadays in TV's, so don't grab a water pipe while also holding onto TV chassis.

Are any voltage readings on the pins of that power supply connector forthcoming?

-------------------------
Location: Far, Far Away

(This post was edited by jts1957 on Aug 30, 2015, 11:42 PM)

arcsum68
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Aug 31, 2015, 4:58 PM

Post #13 of 27 (5240 views)
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Re: [jts1957] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Here are the pin readings with power on, ground is just a - if it really was ground.

TV ON
Pin Legend Reading
1 Power ON/OFF - 1.75
2 H_Sync 0.8
3 STB 5.3V - 5.14
4 GND -
5 GND -
6 GND -
7 13VS 12.46
8 13VS 12.47
9 GND -
10 GND -
11 GND -
12 GND -
13 5.3V 5.14
14 5.3V 5.12
15 5.3V 5.14
16 5.3V 5.12
17 GND -
18 GND -
19 13Vm 12.46
20 GND -
21 13Vm 12.46
22 13Vm 12.46
23 INV ON/OFF - 5.07
24 NC 1.7
25 E-PWM 1.03
26 GND -
27 DET_5 -21.9
28 GND -
29 GND -
30 GND -

This is with the TV OFF - is ground or no reading
Pin Legend Reading
1 Power ON/OFF - 21.3
2 H_Sync -
3 STB 5.3V - 5.17
4 GND -
5 GND -
6 GND -
7 13VS -
8 13VS -
9 GND -
10 GND -
11 GND -
12 GND -
13 5.3V 6.5
14 5.3V 6.6
15 5.3V 6.5
16 5.3V 6.6
17 GND -
18 GND -
19 13Vm -
20 GND -
21 13Vm -
22 13Vm -
23 INV ON/OFF - 5.6
24 NC -
25 E-PWM 6.5
26 GND -
27 DET_5 6.5
28 GND -
29 GND -
30 GND -

(This post was edited by arcsum68 on Aug 31, 2015, 5:01 PM)

jts1957
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Aug 31, 2015, 7:53 PM

Post #14 of 27 (5233 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

What reference were you using for readings?

INV ON/OFF at the PS pin with CN802 unplugged?
Careful that you don't slip and accidentally short to an adjacent pin(s). If you examine the foil side of the PC board, you may be able to find a point that is safer (or you could 'tack' a short wire to pin and measure to that.

-------------------------
Location: Far, Far Away

arcsum68
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Aug 31, 2015, 8:42 PM

Post #15 of 27 (5230 views)
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Re: [jts1957] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Everything plugged in and measure at the back of the plug. I took the measurements several times and got the same results each time.

jts1957
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Aug 31, 2015, 9:09 PM

Post #16 of 27 (5228 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Quote

ground is just a - if it really was ground.

Measuring from the correct ground point to another ground will give NO reading,
'What reference were you using for readings?' = What was the ground point that your black meter lead remained on for ALL your measurements?

Presuming it was a valid point, next measurement would be:
INV ON/OFF at the PS pin with CN802 unplugged?
Careful that you don't slip and accidentally short to an adjacent pin(s). If you examine the foil side of the PC board, you may be able to find a point that is safer (or you could 'tack' a short wire to pin and measure to that.

-------------------------
Location: Far, Far Away

(This post was edited by jts1957 on Aug 31, 2015, 9:10 PM)

arcsum68
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Sep 14, 2015, 2:22 AM

Post #17 of 27 (5165 views)
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Re: [jts1957] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Ground was a screw holding one of the brackets on the rear of the case. I tested multiple locations and all gave the same readings.

I will test the rear of the board with the CN802 unplugged next and report back.

arcsum68
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Sep 21, 2015, 8:08 PM

Post #18 of 27 (5127 views)
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Re: [jts1957] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Pulled the board and with it unplugged the INV ON/OFF pin is reading 13.07

Whats next? Looks like thats more than my initial measurement.

jts1957
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Sep 22, 2015, 1:39 AM

Post #19 of 27 (5122 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

ANY convenient point on the metal LCD panel will be your GROUND. I'd suggest using a wire with an alligator clip at either end (aka: an alligator clip jumper) connected between the LCD panel and Black meter probe.
Fully secure boards. Hook up / plug in all connectors back to pre-set back removal condition. Be sure you have an ACTIVE input connected AND selected.
I need to know the voltage on the following pins, FIRST while CN802 is plugged in (from pictures in the service manual, if your test probe is thin enough, you should be able to probe the metal crimp where the wires enter the connector) & SECOND the SAME points while CN802 is unplugged. Another way to visualize this is I want the voltage readings on the line while CN802 is connected, and then I want you to make the SAME voltage readings ONLY from the Power supply board ... NO Main board lines possibly loading down the circuit.

Pin 1 = ?
Pin 23 = ?
Pin 24 = ?
Pin 25 = ?
Pin 27 = ?

-------------------------
Location: Far, Far Away

(This post was edited by jts1957 on Sep 25, 2015, 1:25 AM)

arcsum68
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Sep 25, 2015, 1:09 AM

Post #20 of 27 (5100 views)
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Re: [jts1957] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

I can definitely clip the ground and measure from the back of the CN802.

Both readings are going to be from the power supply board?

I am just making sure, you noted "main board" in your previous comment which to me would equate to the "motherboard/input board"not the PSU. Not sure I would get any readings from the input board without the PSU connected, hence my assumption.

jts1957
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Sep 25, 2015, 1:28 AM

Post #21 of 27 (5095 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

You're right. Edited last line of my last (post) to correct.

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Location: Far, Far Away

arcsum68
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Sep 26, 2015, 1:45 AM

Post #22 of 27 (5077 views)
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Re: [jts1957] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

OK

PSU Plugged in with active source

1 =.87v
23 =2.2mv (starts off around 14 and slowly drops down)
24 =5v
25 =2.5v
27 = -18.6v

PSU Unplugged from mainboard but other connections complete

1 =.787v
23 =1.3mv (starts off around 14 and slowly drops down)
24 =5.08v
25 =5.25v
27 = -.2v

jts1957
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Sep 26, 2015, 4:37 AM

Post #23 of 27 (5071 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Your back lights coming on but not staying on would tend to indicate a bad Inverter/Power Supply board or defective lamp(s). http://imgur.com/6Aaz5uJ

I'm assuming Inverter On/Off goes higher than 'millivolts' with the PS plugged in AND TV 'off.' (unless you mean 14 volts & slowly drops).
Since set has sound during all of this, Power ON appears to be active low. I'm also assuming INV On/Off is also active low.

http://imgur.com/XsvV6RA
There is a lot of information that I'm giving a wide interpretation and there appears to be an error regarding the OSD (Arrow down should say 'No'). Many lead to possible Main board failure

I'm leaning towards I/P or bulb(s).

-------------------------
Location: Far, Far Away

arcsum68
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Sep 26, 2015, 4:35 PM

Post #24 of 27 (5058 views)
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Re: [jts1957] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

Thanks JTS, it was definitely mv, I checked that one a few times because it didnt seem right.

Sounds like it's a gamble on mainboard vs PSU. This TV has never been a primary TV, it was used in a den as a secondary TV until it stopped working so I do not suspect that the bulbs are end of life.

Repair or replace would be an easier decision if the parts were not so hard to find.

jts1957
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Sep 26, 2015, 6:46 PM

Post #25 of 27 (5057 views)
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Re: [arcsum68] Samsung ln52b630n1fxza no backlight but has sound and pic [In reply to]	Can't Post

mv? http://www.computerhope.com/unix/umv.htm

I've worked on many computer monitors were bulbs were bad with only a little over 10,000 hours of use (40,000 - 60,000 hours was spec'd).

Unless you want to try troubleshooting the I/P board, obtain through a reputable source (ie. SJ making sure that they have more than just the one in stock, if possible), replace it and hope for the best.

My thoughts are:
1) panel has one or more defective bulbs, they try to light, I/P senses a lamp error and shuts down inverter.
2) Inverter portion of I/P board has a bad component (Open transformer winding, bad output device that drives the transformers, or even a defective part in the feedback to detect bulb error).

What's hard to find?
http://www.samsungparts.com/...px?model=LN52B550K1H don't hold your breath on this one.
https://www.encompassparts.com/...N44-00267B/Ac_Vss(i) Atlanta, GA - In Stock

To paraphrase Ron.M: It's your TV / money / call

-------------------------
Location: Far, Far Away

(This post was edited by jts1957 on Sep 26, 2015, 6:47 PM)

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