Floaty Image on modded 60 hz SMD SONY BVM-14G5

[Kaspar84]

Hey!
I am a fresh buyer of the Sony BVM-14G5 TV. I hooked up my modified Sega Mega Drive console and, as long as 50 hz is beautifully rendered after switching to 60 h, the image starts to float slightly. The old CRT TV was all ok. I do not know if it's a hardware problem, or just switch something on a complicated menu. Thanks for the help!

[werk91]

Haha! This is the exact reason I switched my Pal MD2 with 60hz mod for a Sega Genesis that's natively NTSC 60hz. I don't want to give you a definite 'there's no solution' but I certainly gave up trying after weeks of switching cables and settings on Extrons, bought a new Sega and all was fine. BVM's just don't play well with out of spec signals (50hz clock modded to run at 60hz).

[theclaw]

A hardware limitation. Correct operation of the Mega Drive requires a separate crystal oscillator for 50hz or 60hz.

[Kaspar84]

The claw / can You help me find tnąc oscillator??
This is ok?
https://pl.aliexpress.com/store/product ... 90283.html

Werk91 / thanks for answer

[mikejmoffitt]

A hardware limitation. Correct operation of the Mega Drive requires a separate crystal oscillator for 50hz or 60hz.

[Citation Needed]

[theclaw]

A hardware limitation. Correct operation of the Mega Drive requires a separate crystal oscillator for 50hz or 60hz.

[Citation Needed]

Nothing to be confused about. When you switch the console between 50hz/60hz, you're literally running it using an incorrect hardware component.
Many RGB TVs don't mind and will be playable that way. But composite/RF are problematic. Sega didn't design PAL systems to support PAL60 (or NTSC), or NTSC systems to support PAL50.

[Kaspar84]

Ok but i put DC on ant on 60hz it's still floaty. So it's not consoles fault.

[werk91]

My Sega Saturn is NTSC natively and has a switch for 50hz too. No problems with it running in 50hz on my PVM. I imagine it's easier for the oscillator to generate lower as opposed to higher signals than what it was made for.

[theclaw]

Ok but i put DC on ant on 60hz it's still floaty. So it's not consoles fault.

Check your RGB cable.
Consumer SCART usually has CVBS (composite video) sync, where professional monitors may expect a plain sync signal.

My Sega Saturn is NTSC natively and has a switch for 50hz too. No problems with it running in 50hz on my PVM. I imagine it's easier for the oscillator to generate lower as opposed to higher signals than what it was made for.

I'm not sure. This seems to be less of an issue for Sega Saturn though.

[Kaspar84]

I will check the cables. However, I am wondering why for 50 hz is all ok and the problems start at 60 hz.

[theclaw]

I will check the cables. However, I am wondering why for 50 hz is all ok and the problems start at 60 hz.

Baffles me. A rather complicated monitor, tons of options and several expansion modules to add video formats.

[Kaspar84]

I will check the cables. However, I am wondering why for 50 hz is all ok and the problems start at 60 hz.

Baffles me. A rather complicated monitor, tons of options and several expansion modules to add video formats.

If the cables are not a problem then I will return the monitor to a professional.

[mikejmoffitt]

A hardware limitation. Correct operation of the Mega Drive requires a separate crystal oscillator for 50hz or 60hz.

[Citation Needed]

Nothing to be confused about. When you switch the console between 50hz/60hz, you're literally running it using an incorrect hardware component.
Many RGB TVs don't mind and will be playable that way. But composite/RF are problematic. Sega didn't design PAL systems to support PAL60 (or NTSC), or NTSC systems to support PAL50.

This is only a problem for NTSC/PAL. RGB TVs have nothing to be concerned about because for them there is no difference. Correct operation of the Mega Drive composite video output requires a separate oscillator.

[theclaw]

This is only a problem for NTSC/PAL. RGB TVs have nothing to be concerned about because for them there is no difference. Correct operation of the Mega Drive composite video output requires a separate oscillator.

Maybe I'm wrong. I thought with RGB on a 60hz modded PAL Mega Drive, you're still using the system clock oscillator made for 50hz, and the sync timing will be slightly off-spec.

[mikejmoffitt]

This is only a problem for NTSC/PAL. RGB TVs have nothing to be concerned about because for them there is no difference. Correct operation of the Mega Drive composite video output requires a separate oscillator.

Maybe I'm wrong. I thought with RGB on a 60hz modded PAL Mega Drive, you're still using the system clock oscillator made for 50hz, and the sync timing will be slightly off-spec.

Actually, digging a little deeper, the PAL megadrive even has the same crystal configuration with one master clock. I suppose the PAL clock is derived from another division of that same clock.

Megadrive's pretty cool in that way!