SNES 1CHIP-03 Color Issues when using RGB

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drybones99
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Joined: Sat May 20, 2023 6:23 pm

SNES 1CHIP-03 Color Issues when using RGB

Post by drybones99 »

My SNES 1CHIP-03 console appears to have color issues; the image has an overall purple tint, though green is not entirely absent from the image. This only happens with RGB; the colors are completely normal over composite. Instead of white, I get a purplish off-white; this is especially noticeable with any grays as seen in the second image, where the darker half of the white brightness scale is totally purple and the blue scale has almost no variation within it. I also installed Voultar’s RGB bypass mod, along with the ghosting fix capacitor, but that didn’t change anything regarding this problem. I should also note that this is a North American SNES console with a North American copy of Super Mario World (the color bars come from the 240p test suite running on an FXPAK-Pro).

I have tried using both CSYNC (which only worked after installing the mod since 1CHIP-03 consoles don’t have CSYNC by default) and sync-on-luma cables, and that didn’t change anything either. This happens both when using my PVM and when using my RetroTINK-5X Pro on my 4K TV.

What could be wrong with my Super Nintendo?

Here are the images:

https://preview.redd.it/9nd32efnpq0b1.j ... a0a04ebfbb
https://preview.redd.it/qysuicfnpq0b1.j ... 6cbbc1425f
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Rock Man
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Location: Southtown

Re: SNES 1CHIP-03 Color Issues when using RGB

Post by Rock Man »

Did you try different cables?

What input method are you using for RGB? DSUB15, SCART, or BNC?
drybones99
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Joined: Sat May 20, 2023 6:23 pm

Re: SNES 1CHIP-03 Color Issues when using RGB

Post by drybones99 »

I have tried multiple cables to no avail; I am using an SNES multi-out to SCART cable from Insurrection Industries and then a SCART to BNC adapter to connect to my PVM. However the pictures I linked to come from my RetroTINK-5X Pro on my 4K TV with the SCART cable hooked directly to it. In both cases this strong blue tint is present.
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Link83
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Re: SNES 1CHIP-03 Color Issues when using RGB

Post by Link83 »

Hmm, based on your posts I guess we can rule out the following as being potential causes:-

-The 1CHIP ASIC itself - because the Composite video output looks fine
-The original S-RGB encoder - because Voultar's bypass didn't fix the issue
-The cables/TV - because you state you have tested multiple

That only leaves the remaining motherboard components on the Blue signal line as potential suspects.

I would guess we can rule out any components between the 1CHIP ASIC and the S-RGB encoder because if these were at fault the same issue should be visible over Composite video as well.

That really only leaves the components between the S-RGB encoder and the MULTI OUT port. I would look into DA13, DA14 and C47 as being possible causes (I believe these are the correct motherboard part numbers connected to the blue signal, but double check with a multimeter since its been some years since I last looked at this) All of them should be removable without causing any issues (IIRC DA13 and DA14 are diode arrays for ESD protection for the Green and Blue signals, and I forget what C47 was for exactly but I know that it isn't a strictly necessary component) Thats assuming you are comfortable with removing/replacing surface mount parts for testing.

Unfortunately I think Voultar's board may fit directly over some of the components making them difficult to remove for testing.

It may also be worth checking the MULTI OUT port for any corrosion, although I can't really see how that would cause this particular issue.
Last edited by Link83 on Tue May 23, 2023 9:25 am, edited 3 times in total.
drybones99
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Re: SNES 1CHIP-03 Color Issues when using RGB

Post by drybones99 »

I should also briefly add that now the composite output seems to be messed up too. There’s no blue in the image over composite now! Only green and red are present, whereas over RGB there’s too much blue; and adding a resistor to the blue line reduces the blue but makes white look yellow since the blueness isn’t uniform across the grays and whites. When I get home I’ll look at some of these other things, but what does the composite missing blue mean for this situation?
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Link83
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Re: SNES 1CHIP-03 Color Issues when using RGB

Post by Link83 »

drybones99 wrote:I should also briefly add that now the composite output seems to be messed up too. There’s no blue in the image over composite now! Only green and red are present, whereas over RGB there’s too much blue; and adding a resistor to the blue line reduces the blue but makes white look yellow since the blueness isn’t uniform across the grays and whites. When I get home I’ll look at some of these other things, but what does the composite missing blue mean for this situation?
That completely changes things, because now the fault could be with the 1CHIP ASIC itself, or with any of the other components between the 1CHIP ASIC and the S-RGB encoder.
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