OSSC dancing pixels Line 5x mode

[gabrielgamer99]

So I recently got an OSSC 1.6 locally used (I believe its from VGP), everything works fine except for line 5x mode which doesn’t work fully
4x mode works perfectly

Video of problem: https://photos.google.com/share/AF1QipOhCKXiajtwHn0JHwz_ub8YGpfKXGI-rtcBdKGUAl9LNMsFPk64V6N5vEwX2Z9Q2Q?key=NzU5aHlhRkVOelpOVF9GeFZiOGswOW9DbDl4MGp3

Reddit post of similar problem: https://www.reddit.com/r/OSSC/comments/lhip0n/artifacts_in_line5x_sparkling_flashing_pixels/

Things I have tried
– New high grade hdmi cables + many different ones I had around
– About 5 different displays
– different power supplies + Usb power bank
– Different systems, Saturn, Genesis, Snes JR, Pc engine (Genesis and Saturn with Hd retrovision)
– Different firmware versions (Including the beta versions)
– Can confirm 480p Line 2x 960p doesn’t have any issues.

I believe this is a problem with the HDMI side of things
Looking for any suggestions or possible solutions for this problem, would like to be able to use 5x mode properly if all possible not sure if maybe im missing a setting to help with the dancing pixels or something

Looking into replacing the IT6613 Hdmi transmitter chip first as maybe that’s a safe bet and its a cheap chip to buy.
(I do SMD Soldering for work)
Thanks.

• This topic was modified 2 years, 8 months ago by gabrielgamer99.

[marqs]

Have you tried the v1.xx series beta firmware? Those kind of errors can be result of FPGA timing violations (should not exist in later firmwares, especially v1.xx series) or damage in HDMI transmitter chip (e.g. one line of a differential pair broken ot disconnected, easy to check with a multimeter diode test).

[gabrielgamer99]

Hello Marqs, thanks for the reply. I did try the beta version. Noticed the version you just put out a few hours ago. Sadly 5x mode still does the same thing, although I noticed 6x mode doesn’t do it (nothing that I notice anyway) only issue I had was it made the left side of the saturn blurry when not in generic 4:3, might be a setting to adjust for that.

I also tried reflowing the solder on the hdmi transmitter chip the other day and that didn’t do anything. When I have more time I will poke around at it with a meter
Do you think replacing the transmitter is the next best step? Since they’re like $2 chips from aliexpress I ordered some to try another.
Thanks

• This reply was modified 2 years, 8 months ago by gabrielgamer99.

[marqs]

Due to TX pixel repetition 6x has lower pixel clock between FPGA and transmitter but higher clock on transmitter output than 5x. That indicates a potential timing bottleneck on FPGA (perhaps bad unit?) instead of the transmitter, but it’s certainly more expensive to acquire and swap. You can replace the transmitter but don’t hold up too high hopes on it solving the issue.

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