Strange picture issues with Micomsoft SC-512 capture card

[Morpheus_79]

Hi there,

A couple of months ago i’ve built an OSSC for a fellow forum member. At first it worked pretty well on his Micomsoft SC-512, while feeding the component output of his PSP or his PS2 into the OSSC. But then some strange behaviour started: the OSSC still worked on his TV, but the SC-512 refused to recognize the HDMI output of the OSSC. Some forum members assumed a faulty SC-512 – but the SC-512 still worked flawlessly with another (borrowed) OSSC.

So he sent me the faulty OSSC and i did some testing on my TV (without the capture card involved). I recognized some crawling pink dots in the black area of the test pattern:

… which were all over the screen in pass-through mode with my PAL SNES (while only occasional visible in 2x and higher output modes) and a flickering output in 4x mode.

So i resoldered all the pins of the FPGA, the IT6613 and the HDMI connector -> without any changes. Then i replaced the IT6613… and that did the trick. The pink dots were gone and the 4x output was stable. The IT6613 was obviously broken.

I sent the OSSC back to him, hoping his capturing issues with the SC-512 are gone too. But sadly they got only stranger. He did some testing and wrote the following about the results:

1. OSSC directly to the monitor -> with the PSP via YPbPr connected, NO PROBLEMS

2. OSSC directly to the monitor -> PS1 games with the PS2 via YPbPr, NO PROBLEMS

3. unplugged everything and inserted capture card into the signal chain

4. OSSC with the PSP connected via YPbPr (test pattern):

5. switched to YPbPr input (to the picture the PSP is outputting):

6. turned everything off and connected the PS2 (instead the PSP) to the component input of the OSSC and turn everything on (test pattern):

7. switched to YPbPr input -> NO PROBLEM

One day later he tried again – now the picture from the PSP seems fine too:

… for now!

So he is confused… and me too. How can any connected analogue video device influence the test pattern? What could be broken too? Is it possible the SC-512 or the component output of the PSP (in some way) have done some harm to the OSSC?

[Author]

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