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Post by dshadoff on Oct 25, 2024 21:10:37 GMT
The quesiton of how colors appear is actually quite complex because there are lot of layers involved. It's true that a CRT has a different colorspace, different phosphor colors, and a different gamma profile than an HDTV... But fundamentally, the HuC6260 produces different colors from RGB than from composite: inside the HuC6260, there is a lookup table which converts RGB to YUV colorspace, and it fundamentally produces slightly different colors/shades than RGB output. A description of the color table is here: furrtek.free.fr/?a=pceyuvThe RGB turns out more saturated, but even the stepwise changes are different... a picture is worth a thousand words: Here is a visual reference of the difference (I could only find a reference on Twitter/X, so I snapshotted since many people don't have access): (click to expand)  As for the ghosting you are seeing, it sounds like it could be a cable issue - either the quality of the cables isn't as good as you might want, or perhaps they aren't properly terminated at the set (usually this is internal, but sometimes requires external - and there are 50-ohm or 75-ohm versions). I don't have those ghosting issues on composite... |
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Post by theoldgodfx on Oct 26, 2024 5:24:15 GMT
Basically on the composite on the AV out port of the CG II with the stock NEC av cable, and on the Krizz EDFX on either the CG II or white PCE, ghosting is barely noticeable, but present. You can spot it lingering off the text on like the menu in Splash Lake, or in the Shinobi title screen as the symbol moves around the screen and settles in with the logo flashing. Again, you have to go out of your way to notice it and be under certain circumstances, but its there on every CRT I have tried so far out of the batch that I currently have (two Toshiba sets, and my Samsung). Ghosting is more noticeable on said instances, and in others when using the EDFX with the RGC MD2 RGB to Component cable (Internal RGB to YPbPr circuit designed by RetroTink for this cable).
On a white PCE I have here, with a 2n3904 s-video mod, the ghosting that happens in the above instances is much more pronounced to where you wont have issues spotting it at all. If I add a s-video mod to the CG II I have on hand, same deal with the ghosting (added it to the CG II temporarily at one point to see if the same thing would happen that was happening on the white PCE). The s-video modification used is the older one that has been around for years now. Removing the resistor from the trace leading to pin 40 to disable composite does not affect the ghosting. Tapping ground from either the expansion port ground locations, or AV port area does not matter. I do not recall this happening years ago when I did s-video modes on Duo and Duo-R systems, so I am curious if this is isolated to the CG and white PCE, and possibly the TG16, concerning that mod.
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Post by dshadoff on Oct 26, 2024 14:25:39 GMT
These days, I would not use that SVideo mod; I would advise zaxour’s TurboNanza.
I’m not familiar with the cables you mentioned, but have you tried any other, high quality shielded (and short) cables for composite or RGB ? Long cables can also introduce this, and it seems that you’ve tried many variations, but the cables sound like they are common between each test.
One last item to check up on is capacitors… these decay over time, and I know people who have not just had their capacitors replaced, but need it done again. This can be for various reasons… either they were replaced a long time ago, and those new ones are now at the of their lives, or the replacement job used cheap capacitors with a short life, or in some cases the job has been done poorly. Probably something to check into. Mouser and Digikey have a wide selection of high quality capacitors, and you can even select lifetime (very few are rated for over 1000 hours). Those places are good and have trustworthy supply chains, so you can trust that they won’t send counterfeits.
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Post by theoldgodfx on Oct 26, 2024 16:05:49 GMT
Caps were replaced on both systems last month with fresh Nichicon caps, and both systems have the jail bar fix applied. The EDFX is made by Krizz, maker of the Everdrive. RGC is Retro Gaming Cables, basically manufacturing scart cables for game systems, and other cable types using circuits designed by RetroTink. www.retrogamingcables.co.ukTapping directly off the AV out port on the Coregrafx II and installing gold plated RCA jacks for AV right by the AV port, and using short Monster RCA cables (older LD era cables) produces the very faint ghosting off some objects/text that is present with the AV port+stock NEC AV cable, or EDFX with Genesis 2 AV cable also. I suspect its there for everyone on the stock AV out, and just possibly eliminated on the end display in most cases. Possibly most people just do not notice it because its not at all as pronounced compared to what it is on the RGB to Component or old Svideo mod to begin with. I mean, you really have to get right on the CRT display to notice it when using the stock AV out and go out of your way to look for it as it requires certain situations to show up. Attachments:
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