This may be off topic, but does anybody have experience with recapping VA2 HDG Model 1 systems? If so, how effective is it at reducing or eliminating the rainbow banding?
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This may be off topic, but does anybody have experience with recapping VA2 HDG Model 1 systems? If so, how effective is it at reducing or eliminating the rainbow banding?
To be honest, it's not really going to reduce rainbow banding.. They did this when new. It's just how it is.
Now go RGB and you won't have to deal with it. ;)
Well recapping my VA3 did help with the rainbow banding.
Huh, didn't for me.. That's one of the few times I could safely say it didn't..
And I have a VA3 also.
I think the rainbow banding dissapears if you replace it's internal clock to the video decoder with a crystal oscillator, I've done the 60Hz mod on my PAL Megadrive and used a 3.58 MHz crystal and I can't see any banding on composite NTSC mode or jailbars when using RGB.
PAL MDs uses a bit different video curcuitry also... DL lines and such... Just because PAL is a more strictly standart, and requres a more complex curcuitry ( yes, in reference variants ).
That's explains why PAL units ( especially MD2s ), often have a noticeably better video quality in standard NTSC 3/58 than native - NTSC variants...
And a little advice, or "how i get rid of rainbow banding on a CXA1645 NTSC MD2s"
Connect a 28pf ceramic capacitor and a 68uH unductor in series between leg 17 and a GND point.
Personally i used a 22pf cap, as i haven't found a 28pf variant.
Or you can use a 8-30pf or any other variable capacitor.
After this, rainbow banding on a VA4 NTSC MD2 was ~3x time less than before ( yes it's still there but not as harsh a it was )
Also, Ace mentioned that external 3.58 mhz crystal do reduces awful edge pixellation on most ( if not any ) NTSC MD2's.
Bring up this topic again, I have an issue with a wavy lines on after the Svideo mod, I removed my RF and the Serial ports, I took the 5v from the pin that the RF left and used the side for grounding, would on of them cause the issue I am seeing? http://i.imgur.com/WY1DvaA.jpg and
I have had exactly this happen under the same circumstances. Removed RF modulator, drew +5v from where the Modulator was and this happened. Moving the wire to a different +5v source fixed it. I'm not sure why; I never investigated further. I had no problem drawing +5v from the same spot when the modulator was still in.Quote:
Originally Posted by douglie007
I usually take +5V from the 7805 voltage regulator itself (rightmost leg). You can also try using a NTE85 instead of a 2N3904 as your luma transistor.
If it helps, I recently did a successful S-Video mod to my Genesis model 1 with a CXA1145 chip. Here is what I did:
I took pin 15 from the CXA1145 chip into the base of a Radio Shack 2N4401 transistor, the collector to pin 19 to gather +5v and the emitter into an NTE 75 ohm resistor then into the S-Video jack.
I took pin 16 from the CXA1145 chip into the positive side of a Radio Shack radial 220uF electrolytic capacitor, then the negative side to an NTE 27 ohm resistor then into the S-Video jack.
I pulled ground from the edge of the motherboard.
I got the nice S-Video jack from Console 5.
Beautiful sharp clear image.
Ill try moving the power first, and if it still doesn't ill try a different transistor
http://i.imgur.com/WOeiqb6.jpg so the power was the issue, I moved it and the pic is awesome, I checked with my meter and I was getting 4.85v from the RF port, and 4.92v off the 7805, but that wouldnt make the wavy look. I wonder if the voltage is carrying some signal on that line that would make for a poor pic.
Glad that worked for you. Perhaps putting a capacitor on that line would solve the problem. It did work fine from the exact same spot while the RF modulator was still there for me.
A few years later, I'm trying to get the svideo off the va7 board. And I'm getting nothing. Is the video chip different on the va7?