Legacy AV In for OSSC Pro

[marqs]

The extra section can be cut off as long as nothing gets shorted due to sawing. GND connection via terminals should not be mandatory for the legacy AV card which still runs at relatively low frequency (2 pins from the IDC are reserved for ground). Retrospectively a PCIe connector (like this) would have been a better choice due to more pins available for GND, but screw terminals would have been needed anyway for fastening cards.

[Hojo_Norem]

Finally got all the bits together to make the extender…

But it doesn’t seem to be very effective.  Tested with a NTSC NES (To be more accurate, a PAL NES with NTSC PPU, CPU and crystal).  Colours initially were correct but degraded after a few seconds.  All the while with flickering green lines and generally unstable.

I’ve verified that all 50 pins are connected with no shorts.  This was not my first attempt, the previous one had a slightly longer cable and the result was there was practicality only green lines.

Works fine when plugged in normally, so I think I can rule out accidental damage but it’s not a deal breaker that it doesn’t work.  More a experiment than much else.  I may consider the possibility of mounting and connecting the AV in PCB internally in exchange for removing the expansion socket… but I think I’ll wait out my warranty before I think about doing that. ^_^

• This reply was modified 5 months, 1 week ago by Hojo_Norem.

[marqs]

While testing RF-equipped Legacy AV board I noticed similar issues with IDC50 extension cable, even short one. It appears grounding / signal integrity degrades enough to cause visible problems.

[Zacabeb]

Now that I’ve gotten a capture card and can measure the levels in screenshots, I’ve found that Y/C, CVBS, and RF all peak at 239 (with HDMI outputting full range.) It seems the conversion from limited range to full range after CSC subtracts 16 from the values correctly, but then doesn’t multiply them by 255/219.

[marqs]

ADV7280 is set to full-range output so it should utilize values between 1-254 (0 and 255 reserved for SAV/EAV codes). CSC coefficients are same as with YPbPr->RGB path so I’d assume the range issue would be visible there too if the coeffs were wrong. I’ll need to debug ADV7280 output in case there is yet another bug in the chip.

[Zacabeb]

Testing further, if the brightness value in the ADV7280 is raised from -32 to 0, nominal values appear to be within limited range, suggesting that with v0.80-t5 the ADV7280 doesn’t expand to full range.

[Hojo_Norem]

I took a look inside the OSSC Pro’s enclosure.  Sure, there’s more than enough room to install the Legacy AV in board internally but no real way to tidily add the sockets.

So, I went vertical.

As you can see here, it works fine.

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