Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

[tom66]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

OK, do you see a point marked "Ve" or "Vb"? Can you test it? Compare it with the panel sticker.

[HamSa1ad]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

Ve is at 69.9

Originally I had measured VR-VE, at 91.2

Sticker shows 85 for Ve & 73 for 2Ve

[HamSa1ad]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

Took a few liberties is the time between responses.

I returned the original X-Main back to the unit & tested its Ve: 72

I scoured the Fast Track Troubleshooting Manual for my model (many thanks for having such items neatly hosted!) and found out what the VR-VE I noted above was for.
I adjusted the Ve back to the sticker. I turned on the unit for a test and saw the attached.
Didn't notice much of a difference in terms of darkness. Although it appears that more of the display shows "sparkles." (Not really too sure if I'm referring to what I've seen appropriately.)

[tom66]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

A small difference like that I don't think would cause your fault.

On the X-main you also have a bank of three red capacitors, poly film type. Top left. Can you probe the voltage across any one? (they are all in parallel)

[HamSa1ad]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

Excuse my lack of knowledge,

But what setting should I be using to test the voltage accross the capacitors, the same DC Volt setting as prior? Also, does the unit need to be powered off & discharged or is this something I could test on the spare xmain I have?

Thank you for your time answering my simple questions

[tom66]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

The same setting should be used, and the TV should be powered on, showing a picture with the board fully connected.

[HamSa1ad]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

Okay,
With black on chassis & red on a single probe on each cap, I got a reading of 104.6 on each cap, working my way down through all 4 of them

Testing the other probe on the same capacitors, in the same fashion, I got a reading of 14.39

[tom66]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

Sorry if it wasn't clear, but what I meant was black probe one end of the capacitor, red end on the other.

[HamSa1ad]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

From the three that I could fully reach I got a reading of 96.1 from each

[tom66]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

Hmm. Not sure about this fault then. Could you try the same test on the Y-main? Also try and locate the Vsc and check this too.
Do you or can you borrow an oscilloscope?

[HamSa1ad]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

Measured Vsc at - 189.6, sticker at -190

Unfortunately I do not have an oscilloscope, perhaps there is one at our office, I'll have to check later

I did not see round red capacitors on my y main that were similar to the ones I tested on the xmain. Instead I tested one's that were red, but flatter, and more rectangular in shape. They read 209.7 on two and 150.3 on another.

Below is the image of the items tested on, first is what I tested on the y-main, followed by what I believed to be the correct poly film type capacitors on the x-main

[tom66]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

If you can borrow a scope, it would be very useful. You would also need a 10X probe. Ideally get a digital scope over an analog one.
Right now, my suspect is control board or Y-main. I'm not certain about the X-main though.

[HamSa1ad]

Re: Samsung PN50C550G1FXZA - Dark Display with ''Sparkles''

Thank you for the advice. I will work towards having one in my possession.

I'll update the thread when I have done so.

Thank you very much for your time, the help has been greatly appreciated & a good learning experience so far!