Samsung le32r32 vertical lines on screen

[Dannyx]

Good day folks. Have a look at this TV to see if you can provide any feedback. When I got it, it had no picture at all. I took the cover off the T-con and measuring around I got no 2.5v on the respective test point - the regulator was dead. Temporarily, I replaced it with an adjustable "off-board" buck converter to see if it would solve at least part of the issue and it did: I now got a picture, but it's got stripes across it like in the picture...I doubt it's a panel issue because the stripes are too even and go across the entire screen, so it would mean BOTH the buffers are faulty - again, highly unlikely. VGH and VGL appear to be correct and all voltages are correct. Am I missing something or is the main IC on that T-con done for ?

[tom66]

Re: Samsung le32r32 vertical lines on screen

Your dodgy buck converter is probably too noisy, try with an LDO.

[Dannyx]

Re: Samsung le32r32 vertical lines on screen

Yes I thought so too.

[R_J]

Re: Samsung le32r32 vertical lines on screen

This is where that scope would come in handy, I bet that buck converter is very noisy and with the scope you could see it.

[Dannyx]

Re: Samsung le32r32 vertical lines on screen

Sorted: replaced the regulator and it's now working, so if you're having the same issue, it could be the regulator U14 Cheers.

[tom66]

Re: Samsung le32r32 vertical lines on screen

Good fix!
Goes to show how noisy those one-hung-lo buck converter modules are.
Perhaps not as noisy as the first buck converter I built, mind. That one was able to kill the camera it was attached to, on accounts of the 3.3V output having a ripple of approximately 2Vp-p

[Dannyx]

Re: Samsung le32r32 vertical lines on screen

I think the actual problem comes down to feeding that noisy power straight into the "VCC" pins of an IC, whereas if you were to use it to power something like an Arudino or other development boards they're normally intended to be used for it's fine, since those have a regulator of their own, so it's essentially regulated AGAIN, before going to the chip/IC whatever, since it made me wonder how those can operate on buck converters like those (my buddy uses those A LOT!)

[tom66]

Re: Samsung le32r32 vertical lines on screen

Arduinos are a hell of a lot less sensitive than a T-con processor anyway, those could probably run off 3.3V from one of these ok.
The 2.5V will be used directly for the processor so that's the biggest issue.

[kgavionics]

Re: Samsung le32r32 vertical lines on screen

The buck converters are switching mode devices, so they generate a lot of noise ( switching noise), that's why they are not used for some applications like High fidelity audio devices and linear regulators are used instead.