Dreamcast Video Flickering Issue

[NateN34]

Hey,

Well I purchased bundle three supposedly broken Dreamcasts off eBay for $20, free shipping. One was a condition model 0, with a blown f1 resistor on the controller port, another was a model 2, that had a fan with a bad bearing and finally there was a model 1, with video issues. I fixed every one of these and now they are working great, but I am stuck on this last model 1 Dreamcast.

Anyway, what happens it will boot up, the controller port works great and it will play games, but it has a HORRIBLE flickering issue. It is really hard to explain, but it will boot almost all the way through the Dreamcast logo, without flickering, but after that, everything in the menu and every game will have horrible flickering. I have replaced the power supply, with 3 others and this issue still occurs and I have also swapped various other parts, but of course the issue resides somewhere on the motherboard.

I am using brand new standard AV/out cables that work on all other Dreamcasts fine. The AV out port on the Dreamcast looks fine, with all pins intact.

Here is a video of this Dreamcast flickering that I have made:



Now, I do have a spare working motherboard to fix this Dreamcast, but I would like to see if it is repairable first.

So, my question is, what do you think is the issue? Could it be some capacitors on the motherboard that are going wonky or do you think it would maybe be the video chip that is bad?

Thanks in advance,
Nate

[APE]

What connection are you using for video?

[NateN34]

Just standard AV cables. These AV cables are brand new and work with all of my Dreamcasts just fine, so not sure if these could be an issue?

lrgscaledcavcable.jpg

[NateN34]

Eh, I am going to just junk this motherboard and use one of my spare working motherboards for it.

The connections look a bit sketchy, almost like the person before me tampered with it and attempted to mod it. So I cleaned up and resoldered those connections. I also tried that stupid heat trick on the video chip, but it still flickers like heck.

Who knows, what the issue could be, but all I know is it is not worth diagnosing.

[APE]

Heatgun=bad idea.

Probably just needs some touch up work on a few solder joints. The A/V connector isn't likely to cause this sort of thing.

[NateN34]

Heatgun=bad idea.

Probably just needs some touch up work on a few solder joints. The A/V connector isn't likely to cause this sort of thing.

Yeah, I knew that heatgun would be a bad idea and could potentially damage it, but decided to give it a shot anyway.

Still works though, after all that heat on the chip.

I guess I will attempt to fix it some other day. I want to get my modded bios installed, before messing with this motherboard again.

[l_oliveira]

Either HOLLY chip (GPU) is damaged or one of the video memory chips are faulty... Don't waste you time with it.