No picture/sound with Mega Drive in 60 Hz modus at OSSC via RGB-SCART and HDMI
- This topic has 3 replies, 2 voices, and was last updated May 15, 2023 at 6:53 PM by
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Hello!
When i try to run games on my „Mega Drive 1“ (the european Genesis) (for example „Streets of Rage I“ or „The Simpsons: Bart vs. the Space Mutants“, both PAL) which has a custom build 50/60 Hz switch and is connected to an OSSC (board version 1.6, firmware version 0.90) via a professionally build retail RGB-SCART cable (which has an extra audio cable going to the audio-in of the MD), i’ll get neither an image nor a sound on my „Sharp Aquos LC-40LE630E“ when in the 60 Hz modus.
The TV says „video format not supported“. In the 50 Hz modus everything runs fine. The SCART socket of the TV is capable of RGB and CVBS.
The OSSC is connected to the TV via a HDMI cable. The TV has three HDMI slots and with none of them i’ll get a picture or sound.
The OSSC settings are all at the defaults, while i also tried „passthru“ instead of „line2x“ (etc.) in the output options.
The OSSC-LCD displays „AV1_RGBS 313-p / 15.55 kHz 49.69 Hz“ (ca.) in the 50 Hz modus and „AV1_RGBS 262-p / 15.53 kHz 59.29 Hz“ (ca.) in the 60 Hz modus.
Why do i not get a picture and sound with this setup in the 60 Hz modus, what is wrong?
Thank you very much in advance!
Hello,
as far as i know, i do not have other consoles wich output a 60 Hz signal that i could try, but i have now had the time to try two other cables on the same display (with the same result) and to try the whole setup on an other display (a LG 55NANO867NA flat screen TV) on which i get a picture and sound in the 60 Hz modus. Also, i get a picture and sound in the 60 Hz modus when the MD is directly connected to the Scart port of the Sharp TV, i forgot to mention that in my first post. On the other display, the OSSC-LCD displays „59.32 Hz“ or „59.36 Hz“ and sometimes it displays these values on the Sharp TV as well (what i also forgot to mention in my first post), so i don’t think that the signal is too far from the NTSC specification for my TV to handle, or can it really be that it is?
How is this technically to explain? The Scart port of the Sharp TV can handle 60 Hz but the HDMI ports of the same TV can not? But the HDMI ports of other TVs can handle 60 Hz? Does the OSSC-LCD display „60.00 Hz“ on true NTSC consoles? Do i need to change the settings of the OSSC or a special HDMI cable?
Thank you very much in advance.
The SCART port on your TV is probably applying some additional image processing, this has often been found to be the case. Even when dealing with consoles like PS2 for instance, that output 480i or 480p, connecting to the OSSC, and then to the TV and just passing the signal through often results in less input lag than connecting via the TVs SCART or component inputs because of additional signal processing that TVs do on these ports.
You will find that a true NTSC console does not run at exactly 60hz (or even 59.94hz as was the broadcast standard) but it is quite a bit closer than the 59.36hz that your system is outputting and, unfortunately, this is occasionally enough of a discrepancy to cause compatibility issues with modern TVs.
There is a high chance you can fix this issue by installing a DFO into your console – https://videogameperfection.com/products/dual-frequency-oscillator/
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