Samsung LN37A450C1DXZA LCD TV with Saturated Image

[XRacerX]

I'm trying to repair a Samsung 37 inch LCD TV that has a saturated white/blue image. Please see the attachments... The original fault was the screen would gradually go red until it was completely saturated. At power-up it had a normal image but as the TV heated-up it would go red. When I received the TV I found it had a constantly white/blue saturated image.

I removed the rear cover and checked the power supply for any signs of bad caps but didn't find anything unusual. I checked all the connections between the Main, T-Con, Power Supply and Inverter boards but didn't find anything wrong. Powered up the TV again and same problem.

I then went into the service menu and did a reset. When the TV powered back on again the image was flipped 180. I went back into the service menu and changed the mirror setting to flip the image back the right way. I didn't take too much notice of the other default settings but I could have sworn they were set at "37" and now they are set at "40". It appears after the reset the main board is now set for a 40 inch. That seems really odd!

Now it appears I cannot access the service menu. With reference to the attachments my original question was is this a main board issue or a T-Con board problem? But now I'm a bit stumped why I got values changing in the service menu following the reset, the image flipping upside down, and I appear to be locked out of the service menu.

Any help would be greatly appreciated.

[tom66]

Re: Samsung LN37A450C1DXZA LCD TV with Saturated Image

I'll bet gamma chip fault. Post a picture of your T-con board. Fourth this week with similar fault.

[XRacerX]

Re: Samsung LN37A450C1DXZA LCD TV with Saturated Image

Thank you Tom.
See pics of the T-Con board. It is part number T370XW02. I'd say the Gamma IC (U202) is an AS15-F if I'm reading the text on the chip correctly. So where do I make the Gamma voltage measurements? I'm guessing the 16 circular pads very close to the ribbon connector? Note there is a VGMA_REF pad near the crystal. Is this my -ve connection point for the DVM?
I figured out why I couldn't access the service menu. I wasn't pushing the buttons on the remote fast enough. You have to be fairly quick pushing Mute-1-8-2. When it didn't work the first time I went slower thinking I wasn't hitting the buttons right. That just made it worse.
Thanks again.

[martino]

Re: Samsung LN37A450C1DXZA LCD TV with Saturated Image

Don't mind me,made a nice circle around the chip,then saw you had it already figured out,lol....Couldn't delete this post

[tom66]

Re: Samsung LN37A450C1DXZA LCD TV with Saturated Image

Check the voltages on the test points labelled VGAMA1 through VGAMA22, whichever are available.

[XRacerX]

Re: Samsung LN37A450C1DXZA LCD TV with Saturated Image

Thank you Tom.
Here are the Gamma voltages:
V1 = 15.6
V2 = 15.6
V6 = 15.8
V7 = 15.6
V8 = 15.6
V10 = 15.8
V11 = 15.8
V12 = 8.1
V13 = 6.3
V15 = 8.7
V16 = 5.2
V17 = 5.0
V21 = 0.5
V22 = 0.4
I entered the voltages into your spreadsheet and the result is fail. I've purchased a new Gamma IC off Ebay. I know a Technician with SMD soldering expertise and will ask him to replace the IC. I'll get back to you with the results...
Thanks again.

Also, I found a Russian website with a load of manuals. Elektro Tanya. I found the manual for the TV plus another manual for the T-Con board. Have you used this site?

[drgears]

Re: Samsung LN37A450C1DXZA LCD TV with Saturated Image

Just received a nice Samsung LN37A550P3F ,,,fired right up,,,good sound ,,pic is washed out,,,was looking for which component to start with,,,this post answered where to start....thanks guys....gbaum

[tom66]

Re: Samsung LN37A450C1DXZA LCD TV with Saturated Image

[ATTACH]85301[/ATTACH]Just received a nice Samsung LN37A550P3F ,,,fired right up,,,good sound ,,pic is washed out,,,was looking for which component to start with,,,this post answered where to start....thanks guys....gbaum

Check T-con fuse and gamma chip voltages.

[drgears]

Re: Samsung LN37A450C1DXZA LCD TV with Saturated Image

Hi tom this one will probably just replace the board,,one site must have bought a truckload of damaged sets ,,has 10 boards available ,,price wasn't too bad 50.00 ,did a surface chip replacement on a vizio set ,,,not so good,,,fat fingers, old eyes,, well,,, need to get larger magnifying setup...
2 caps 1000mf /35 volt are bad,,,new ones coming from this site..replacing a total of 5......

[drgears]

Re: Samsung LN37A450C1DXZA LCD TV with Saturated Image

To update ,,,,new t-conn board installed,,,4 caps replaced,,,,,plays perfect!!!! total investment $63.00....really love "dumpster" brand TV's ,, best value for the $$$$.....