Breadbin C64 with bad ghosting in video output

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fuzzybad
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Breadbin C64 with bad ghosting in video output

Post by fuzzybad »

I've got a 'breadbin' C64 which exhibits pretty bad ghosting in the video output. Can anyone offer advice? I'm thinking it might be caused by a bad capacitor, probably in the video section.

Image


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Re: Breadbin C64 with bad ghosting in video output

Post by dlfrsilver »

The c64 was from 1983 if you have the breadbin model, so if your question is must i change the capacitors, the answer is yes of course. They're dead since quite a bit of time now.

Note also that some VIC-II chip have this problem, and you need the lumafix64 addon, which allows to reduce the jail bars effect :)

That's what i have on mine + brand new capacitors everywhere possible :)
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Re: Breadbin C64 with bad ghosting in video output

Post by fuzzybad »

Thanks for the reply. This is a Rev A board, Assy # 250407.

I'm aware of the lumafix solution, but it's rather expensive and I'm not sure that it will solve this issue. I'm not just talking about the vertical bars, which many VIC-II chips exhibit. If you look closely at the left side, the 'READY' text is smeared all up and down the screen, and about 5 characters to the right.

The main system caps have already been replaced; I'm not about to replace the numerous tiny caps unless they have some impact on the video circuit.

I'm thinking of attempting the mod to remove RF modulator, from my understanding this will improve picture quality.
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Re: Breadbin C64 with bad ghosting in video output

Post by dlfrsilver »

if it works, can you post back on this matter ?

PS : i have changed ALL the capacitors including the small ones. And it clearly make a change. I was amazed to see that after replacing the capacitors, the display were really better (i had even GFX artifact on the letter on screen in games), and a sort of blurry effect.

After replacing the caps, the video quality changed for the best. And then i tweaked again the lumafix, and now i have something really good.
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Re: Breadbin C64 with bad ghosting in video output

Post by fuzzybad »

I will post back in this thread my results. It will probably be next week before I get around to working on it some more..
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Re: Breadbin C64 with bad ghosting in video output

Post by eslapion »

The ghosting you mention is not so obvious on the picture you posted. You should zoom-in and increase the contrast.

Exactly what type of connection do you use between the 64 and the display?
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Re: Breadbin C64 with bad ghosting in video output

Post by fuzzybad »

Here's a close-up & enhanced portion of the image I posted earlier. I'm connecting via S-Video, and have several other C64's which look great using the same cable and same display.

Image

I've started to mod this 64 to remove the RF modulator, so unfortunately I can't take any new screenshots until that's done..
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Re: Breadbin C64 with bad ghosting in video output

Post by fuzzybad »

Last night I removed the RF modulator box from this 64, and I have a strong feeling this may be to blame for the poor signal. Here are a couple pics of the modulator; it appears something leaked (perhaps a capacitor) and this may have caused damage on the underside of the board.

Image

Image
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Re: Breadbin C64 with bad ghosting in video output

Post by dlfrsilver »

Indeed there is goo all over, the big blue capacitor has leaked big time, and ate the tracks on the underside :(
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Re: Breadbin C64 with bad ghosting in video output

Post by fuzzybad »

Update on this.. I have attempted the S-Video mod, following this schematic:
Image

Here is my breadboard:
Image

And here is resulting video output:
Image

Obviously, something is not quite right here. It's looks like I'm only getting Chroma+Sync, no Color info. And what's with all the vertical striping?

Any ideas?
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