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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
Samsung LN52A860S2F backlight immediate shutoff

 
 


thanatos2k
New User

Nov 8, 2015, 8:23 PM

Post #1 of 6 (1381 views)
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Samsung LN52A860S2F backlight immediate shutoff Can't Post
I've got a Samsung LN52A860S2F, which is the blue version of the LN52A850S1F. Service manuals are out there but behind paywalls but don't mind picking it up if it'll help.

I've had the TV since 2008, problem started when I moved the TV from a wall downstairs to my bedroom wall last weekend. Basically, the TV turns on and the backlight turns on correctly, then after about 1 second there's an electronic click from the backlight inverter board region and the backlight shuts off. The rest of the TV remains functional though, including sound, picture (with flashlight aid), input selects, etc.

The power baord (BN44-00240A) measures 26.1v at the 24v supply to the backlight boards if that helps. The board has a bunch of test points written on it so I can test all those voltages fairly easily if that would help.



jts1957
Veteran


Nov 8, 2015, 9:29 PM

Post #2 of 6 (1378 views)
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Re: [thanatos2k] Samsung LN52A860S2F backlight immediate shutoff [In reply to] Can't Post
Same connector(s) Pins 1, 2, 3 & 4 readings would also apply. Error out, Enable, Dim.

Since problem occurred/started during / after a move, obvious possibilities would have to include: Physical damage - unit fell, was hit, set was 'racked' - any of which could, for example, break a CCFL bulb.


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Location: Far, Far Away


thanatos2k
New User

Nov 9, 2015, 1:39 AM

Post #3 of 6 (1372 views)
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Re: [jts1957] Samsung LN52A860S2F backlight immediate shutoff [In reply to] Can't Post
Both connectors read the same on pins 1-4:

1: 2.45v - E-PWM
2. 3.58v - I-PWM
3. 5.15v - Backlight On/Off
4. 0.00v - Inverter

I didn't drop it but I did carry it alone and it's thin, flexes, etc, so very well could have cracked a backlight.


jts1957
Veteran


Nov 9, 2015, 1:58 AM

Post #4 of 6 (1371 views)
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Re: [thanatos2k] Samsung LN52A860S2F backlight immediate shutoff [In reply to] Can't Post
And are those voltages in Standby (with the set plugged in but NOT turned ON)? or in 'Run' (set plugged in and power has been pressed)?


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Location: Far, Far Away


thanatos2k
New User

Nov 9, 2015, 4:00 AM

Post #5 of 6 (1367 views)
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Re: [jts1957] Samsung LN52A860S2F backlight immediate shutoff [In reply to] Can't Post
That one was with power on after the backlight has turned off. Just measured all 4 at 0 in standby.

Did another set right after I hit power (before the backlight would turn on) and 2-4 are the same, 1 starts at 3.15v and then drops to 2.6 a couple seconds before the backlight turns on.


jts1957
Veteran


Nov 9, 2015, 10:04 AM

Post #6 of 6 (1364 views)
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Re: [thanatos2k] Samsung LN52A860S2F backlight immediate shutoff [In reply to] Can't Post
Why pay for free? NO schematics though.
http://documents.tips/...-service-manual.html


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Location: Far, Far Away

 
 
 


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