Samsung LN32A550 Backlight Issue

[stith]

Re: Samsung LN32A550 Backlight Issue

When looking inside the panel with the lights on, it seemed like two or so light halfway. I'll work on getting some more images of behind the lcd panel today. I was also thinking maybe a shortage of power. The 24 volts might be good but at what wattage or current draw. .not sure i have the instruments to measure that.

[stith]

Re: Samsung LN32A550 Backlight Issue

More information! In the form of pictures...

Also, no capacitors between lamps?

[cheebster]

Re: Samsung LN32A550 Backlight Issue

just wondering, did you try to connect 1 at a time the ccfls on the inverter, do the ccfls light up this way ? it might be 1 ccfl that is bad that the inverter is struggling with..

like, connect first, then try just the second one, then third.. check each of them

[stith]

Re: Samsung LN32A550 Backlight Issue

just wondering, did you try to connect 1 at a time the ccfls on the inverter, do the ccfls light up this way ? it might be 1 ccfl that is bad that the inverter is struggling with..

like, connect first, then try just the second one, then third.. check each of them

This is what I just tried. Only the top 4 lamps would light. I also tried it with no lamps and the inverter board still made a static noise from near the middle top of the board.

[tom66]

Re: Samsung LN32A550 Backlight Issue

You could have a loose connection near there then - try reseating all lamp connectors, make sure they are secure, etc.

[tibimakai]

Re: Samsung LN32A550 Backlight Issue

Did you measure all 8 FET Transistors?

[stith]

Re: Samsung LN32A550 Backlight Issue

You could have a loose connection near there then - try reseating all lamp connectors, make sure they are secure, etc.

With all lamps unpluged, the noise persists. I can reconnect them all and see what i dont think it will change.

[budm]

Re: Samsung LN32A550 Backlight Issue

So what resistance reading on each pair of the Pink and White wires are you getting, I am expecting it to be around 3K or more since U-shape lamp will need really high voltage to drive than the straight lamp. And by the way, the lamps stay half way lit like that without going into shutdown?

[stith]

Re: Samsung LN32A550 Backlight Issue

So what resistance reading on each pair of the Pink and White wires are you getting, I am expecting it to be around 3K or more since U-shape lamp will need really high voltage to drive than the straight lamp. And by the way, the lamps stay half way lit like that without going into shutdown?

I have a basic meter for testing resistance. I was getting about 2.5k ohms on the connectors. Also the tv stays on as is with half the lamps half way on. I did a sniff test for burnt components and it checks out fine.

[budm]

Re: Samsung LN32A550 Backlight Issue

It is really strange that it did not go into shutdown mode due to lamps not fully lit. Another thing that does not make sense either is that if you have just one lamp connector connected, I would expect you to see it fully lit for a second (before it goes into shutdown mode) since it will be the only one that draws the current.
I wonder what will happen if you change those 6 caps on the inverter board.

[stith]

Re: Samsung LN32A550 Backlight Issue

Is there a factory reset button mash i can do for this lcd? Maybe a setting is bugged out.

[tom66]

Re: Samsung LN32A550 Backlight Issue

Service Mode (1):
TV in standby.
On remote: INFO - MENU - MUTE - POWER.

Service Mode (2):
TV in standby.
On remote: MUTE - 1 - 8 - 2 - POWER

Try either - see which works. Second one I think is US only, first one works on most Samsung TVs.

When in service mode look for factory reset option.

[drpj23]

Re: Samsung LN32A550 Backlight Issue

If that doesn't work ..... how do all those HV transformers check out?
And two, I second also checking the FETs (as tibimakai said) and possibly changing those caps (as budm said)

Would the ballast caps be under the inverter board?

[freakaftr8]

Re: Samsung LN32A550 Backlight Issue

I'm on the inverter transformer failure. Just repaired a Westinghouse 32" LCD that Both transformers Khmer good but one was burned on the inside. Not visable on the board. Similar instance. Is one transformer getting warmer than the others?

[stith]

Re: Samsung LN32A550 Backlight Issue

Sorry for the short hiatus. I tried the factory reset (the MUTE - 1 - 8 - 2 - PWR worked) but came back the same way it was already.

I can try measuring the FETs...

I don't have replacement capacitors to replace the 6 that are on top of the board so I don't think I'll do that just yet.

I just noticed these marks on my board. I circled them with red on the picture. Could this mean some of those components failed and damaged the board? Or is it just bad manufacturing...I'm really suspecting the inverter board to be the culprit here and I think I might just need to replace the whole thing.

[budm]

Re: Samsung LN32A550 Backlight Issue

It looks like someone had replaced the transformer and the caps, they are solder flux.

[stith]

Re: Samsung LN32A550 Backlight Issue

It looks like someone had replaced the transformer and the caps, they are solder flux.

I had gotten this TV from newegg.com a few years ago. It wasn't a refurbished TV.

[tom66]

Re: Samsung LN32A550 Backlight Issue

More than likely, those caps and transformers are hand-retouched as they are not designed to be surface mounted by machine. But it makes me wonder how much additional cost that brings to say using SMD caps and transformers.

[kc8adu]

Re: Samsung LN32A550 Backlight Issue

darfon inverter.
bad transformers.
at least most are cheap and availible.

[stith]

Re: Samsung LN32A550 Backlight Issue

I order a new board of the exact same manufacturer and number for $15.99. Should be here mid next week. See you all then.