OSSC self built. Weird color issue.

[oneleaftree]

Hi there,

I recently finished building an OSSC 1.6 and have a rather odd issue where there is a weird gradient pattern at the top of the screen. It gets worse depending on how bright the overall image is.

I’ve tried multiple PSUs, HDMI Cables, Sources and Displays and the problem is consistent with all of them.

The issue does not occur when using the VGA input.

If anyone could shed some light, that would be most appreciated.

Cheers.

[DevLatron]

Hey.

that might be a solder bridge, or one of the resistors for the inputs isn’t soldered on correctly if all your sources were on the same input.

Check another input if you haven’t already, and maybe post pictures (closeups) of the board in the DIY forums.

Edit: Didn’t read that VGA input thing… try the following:

Check the resistors R4 to R9.

Also check all pins of the THS7353 at U17 for solder bridges.

After that check the TVP7002 for solder bridges on the inputs.

[oneleaftree]

Thank you for the suggestions!

I’ve had a good look over the board under a microscope and can’t see anything that looks out of place.
No bridges, missing components and solder bridges etc.

Not sure where to go from here. The fact that it doesn’t occur when using the VGA input does narrow it down somewhat but I just don’t know where to go from here.

[DevLatron]

Make some pictures and post them in the DIY aubforums, and I’ll have a look at things.

[oneleaftree]

Will try and get some photos up soon. Thanks again!

[marqs]

Are you sure THS7353 input coupling caps (C3-C7, C12) are correct value? You could also try with higher that default value, e.g. 4.7uF.

[oneleaftree]

You were bang on!

I measured the Caps you mentioned and I accidentally used 1nf instead of 1uf.

Not sure if the other Caps needed changing but I swapped all 26 just in case.

Thank you!

[Author]

Posts