Samsung - LE32A457C1D - screen artifacts

[ocf]

Hello Badcapers,

This LCD TV turns on without fail but shows coloured lines on screen, see images below.

I have tested voltages from PSU to mainboard and PSU to Inverter, all seem ok.

No bulging caps or other obvious damage.

Reseated all cables and ensured PCB's were secure.

Do Samsung LCD's have a test pattern generator like Plamsmas do? I read that most don't.

If the TV is left alone for a while it settles down and majority of the lines disappear other than a rectangle in center of screen. As soon as I hit menu or source the screen lights up multicoloured like its christams. Actually quite relaxing to look at.

I haven't looked at the control board yet as it's fairly difficult to get at.

Any suggestions?

[LITEZONER]

Re: Samsung - LE32A457C1D - screen artifacts

I would try the freezer spray just an air spray can upside down, when the line appear spray components one at a time to which one is causing the problem, I have not heard of any test pattern on these, but i am not positive. when you say left alone, do you mean off?

[ocf]

Re: Samsung - LE32A457C1D - screen artifacts

I would try the freezer spray just an air spray can upside down, when the line appear spray components one at a time to which one is causing the problem, I have not heard of any test pattern on these, but i am not positive. when you say left alone, do you mean off?

When I say left alone I mean switched on but not pressing buttons or attaching inputs

[ocf]

Re: Samsung - LE32A457C1D - screen artifacts

I done the opposite and gave the boards a gentle heating with a heatgun. No difference to image after mainboard PCB and Tcon were heated

TCon and Mainboards for this TV are cheap as chips, any way to definitively tell if the panel is bad?

[ocf]

Re: Samsung - LE32A457C1D - screen artifacts

Tried freezing some areas of PCB, no difference. The largest IC is under a EM shield so I will have to remove that to ensure it gets cold properly.

[vinceroger69]

Re: Samsung - LE32A457C1D - screen artifacts

tab bond issue maybe?

[CapLeaker]

Re: Samsung - LE32A457C1D - screen artifacts

unplug one side of the tcon, while the other is connected, then vise versa. See what happens to the screen.

[ocf]

Re: Samsung - LE32A457C1D - screen artifacts

I could try applying some pressure to the bonds to see if the relieves the image a bit.

Where are the tabs located? I am assuming along the top or bottom of panel, will they be on the same side of the panel where the TCon board is located

[ocf]

Re: Samsung - LE32A457C1D - screen artifacts

unplug one side of the tcon, while the other is connected, then vise versa. See what happens to the screen.

Both ways the panel lights but black screen.

[ocf]

Re: Samsung - LE32A457C1D - screen artifacts

This tv has been worked on before, there are two pieces of electrical tape at base of mainboard, looks the last person put them there to prevent the edges of the boards shorting.

Also the mainboard looks like it has been swapped out possibly an official samsung repair. The mainboard has a label on it. "M.Andi B-Team", I want the A team dealing with my issues thank you very much!

[ocf]

Re: Samsung - LE32A457C1D - screen artifacts

Took of the frame to get access to the tabs, they all look fine and no change to image on screen when I apply pressure.

[CapLeaker]

Re: Samsung - LE32A457C1D - screen artifacts

Can we see a high res, straight shot picture of your tcon board?

[ocf]

Re: Samsung - LE32A457C1D - screen artifacts

http://www.placilcd.ro/images/produc...1362028164.jpg

[CapLeaker]

Re: Samsung - LE32A457C1D - screen artifacts

aah! That's why the panel went black. It doesn't have 2 ribbon cables that go to the LCD, it only has one.

Check Q1 if it is shorted or not.

[ocf]

Re: Samsung - LE32A457C1D - screen artifacts

Packed it in for the night. I will let you know what the results are tomorrow.

If Q1 has been shorted would it be an indicator of a bad panel? I watched a video recently where if a specific TCon transistor was blown it was 75% chance the panel was bad and a new board would go the same way as the old one.

[CapLeaker]

Re: Samsung - LE32A457C1D - screen artifacts

you got it. Personally I'd risk a $20 tcon board.

[ReeceyBurger123]

Re: Samsung - LE32A457C1D - screen artifacts

Looks like Tcon to me, if I remember Budm had the same chassis which the Tcon had a shorted diode package.

[ocf]

Re: Samsung - LE32A457C1D - screen artifacts

I've checked the transistor, on my board its marked QT1, I am seeing resistance measurements in the mega ohms between most leads. A couple of readings were in 100's of K

If Q1 was shorted I would see no resistance or very low resistance between two of the leads?

When testing it was exhibiting some strange characteristics, resistance readings not staying steady (possibly due to self ranging DMM) and also same two legs tested twice gave a wildly different reading.

How do these differ from IGBT's, are they just used for switching in lower power circuits? What is the purpose of this transistor on the Tcon board please excuse the newb questions

[antas]

Re: Samsung - LE32A457C1D - screen artifacts

Could someone help me to find the schematic for this t-con board, please? I changed two t-con boards, but the panel still on backlights only ... Any ideas, guys?

[dskall]

Re: Samsung - LE32A457C1D - screen artifacts

Are you getting power to your t-con?