Turbo Grafx 16 RGB mod woes

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bighead1
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Turbo Grafx 16 RGB mod woes

Post by bighead1 »

I recently got Voultar's RGB mod for my Turbo Grafx 16. I have installed it and am having trouble getting a picture. I believe the issue relates to sync. I get a picture but the screen is constantly rolling, like a old picture on broadcast TV. The picture is also heavily skewed. I am using a Genesis 2 multi-out. I have tried 2 Genesis cables, one with the resistors/capacitors and one without any additional hardware. I have also tried it with and without the low-pass filter, and with and without the LPF filter switch on my gScart switch flipped. Nothing seems to change the picture. Picture of my board attached. My soldering is not the best. Any help/tips would be appreciated. https://imgur.com/a/G2gOOz3
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Guspaz
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Re: Turbo Grafx 16 RGB mod woes

Post by Guspaz »

The mod outputs c-sync, it sounds like your genesis cables are wired for composite sync. The Genesis 2 pinouts has two different pins for composite sync and c-sync.
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Josh128
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Re: Turbo Grafx 16 RGB mod woes

Post by Josh128 »

Composite sync is c-sync. Which is entirely different from sync on composite video, which is what you mean. No need to confuse the poor guy, lol.
bighead1
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Re: Turbo Grafx 16 RGB mod woes

Post by bighead1 »

Composite Sync and C-Sync are the same thing, correct. Blame the SCART people for having C-Sync and Sync on composite be two separate things :)
bighead1
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Re: Turbo Grafx 16 RGB mod woes

Post by bighead1 »

Another question, does +5V need to be wired to the port for for this to function correctly? I did not see anything about doing this. I pulled +5V from the 7805 and wired it to the multi-out just in case, but it did not make a difference
fernan1234
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Re: Turbo Grafx 16 RGB mod woes

Post by fernan1234 »

Do you have an OSSC around to test? My experience with one of these specific RGB boards was that they seem to work perfectly when connected to an OSSC, but with otherwise the same cabling they can't output a sync that works with some RGB monitors when connected directly.
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Guspaz
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Re: Turbo Grafx 16 RGB mod woes

Post by Guspaz »

Right, but my basic point stands, the Genesis 2 pinout has two different pins for cvbs and csync, and it sounds like you wired sync to the wrong pin for your cable. Remember that SCART does not have a separate sync pin, nor would any 4-connector BNC cable.
ldeveraux
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Re: Turbo Grafx 16 RGB mod woes

Post by ldeveraux »

What's your cable termination? I don't know what a Genesis 2 multi-out is. Is it SCART? If so and you're going through a gscartsw, the TG16 RGB mods are very finicky with that switch.
bighead1
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Re: Turbo Grafx 16 RGB mod woes

Post by bighead1 »

Do you have an OSSC around to test?
I am using an XRGB framemeister. I have plugged it in directly, and through my gSCART switch. I have also toggled the sync regeneration switch on my gSCART. No change
What's your cable termination? I don't know what a Genesis 2 multi-out is.
I am connecting this RGB mod to a Sega Genesis 2 (Mega Drive 2) 8 pin multi-out DIN. From there it is going to a SCART cable.
Genesis 2 pinout has two different pins for cvbs and csync, and it sounds like you wired sync to the wrong pin for your cable.
I did check on this. Pin 4 on the multi-out is Csync, and Pin 5 is CVBS. I have a wire between Pin 44 of the HU6260 to the RGB mod, and from there it goes to Pin 4 of the multi-out
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Guspaz
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Re: Turbo Grafx 16 RGB mod woes

Post by Guspaz »

Did you check that you have continuity between pin 4 on the din connector (on the TG16 side, not the cable side) and pin 20 on the SCART connector?
bighead1
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Re: Turbo Grafx 16 RGB mod woes

Post by bighead1 »

I believe I did, but I will check again when I get home.
bighead1
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Re: Turbo Grafx 16 RGB mod woes

Post by bighead1 »

Pin 4 to pin 44 is good. Just for a test I wired it to pin 5 (CVBS) and got no video output at all. After reflowing pretty much everything I have success...Sort of. If I connect this to my CRT (through a Shinybow YPrPb-SCART converter) it works fine. If I patch this through my gScart to works fine going to my CRT. However, my Framemeister does not seem to like it at all. I get no video, not a blip. Audio works great :)
bighead1
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Re: Turbo Grafx 16 RGB mod woes

Post by bighead1 »

Turns out flipping the Sync regeneration switch on my gScart switch did it. Now I have crisp RGB out of my TG16! Thanks all!
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