NES graphics issues

Discuss technical or other issues relating to programming the Nintendo Entertainment System, Famicom, or compatible systems.

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capsulej
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NES graphics issues

Post by capsulej » Sat Jan 19, 2019 12:06 am

I seem to be having a issue with flashing horizontal lines on my NES. Switching the game has no effect. Anyone encounter this before?

https://imgur.com/a/O8f1SFi
Last edited by capsulej on Sun Jan 20, 2019 4:04 pm, edited 1 time in total.

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Controllerhead
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Re: NES graphics issues

Post by Controllerhead » Sat Jan 19, 2019 3:59 pm

Yep. It's a PPU hardware error in every NES. More info here:

https://forums.nesdev.com/viewtopic.php ... 4&start=30

EDIT: Nevermind. This glitch is not that glitch. Carry on.
Last edited by Controllerhead on Sun Jan 20, 2019 4:33 pm, edited 1 time in total.
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lidnariq
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Re: NES graphics issues

Post by lidnariq » Sat Jan 19, 2019 5:10 pm

This glitch is not that glitch.

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Fisher
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Re: NES graphics issues

Post by Fisher » Sun Jan 20, 2019 9:04 am

Aren't vertical lines caused by bad contacts on the PPU data bus?
Unfortunately I couldn't see the picture (or video) you posted as reference. :-(

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tokumaru
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Re: NES graphics issues

Post by tokumaru » Sun Jan 20, 2019 9:32 am

I didn't see any vertical lines, the glitches looked pretty horizontal to me.

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Fisher
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Re: NES graphics issues

Post by Fisher » Sun Jan 20, 2019 11:39 am

I remember to have read a topic about a guy with some small horizontal lines problem.
I can't find the topic right now and my cell phone just can't open the example that was posted...
But if I remember correctly, it was a problem with the 74'373.
Could this be the same case?

lidnariq
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Re: NES graphics issues

Post by lidnariq » Sun Jan 20, 2019 11:48 am

Describing the video: the glitches are random single incorrect fetches of the wrong tile data. Attribute data seems to be always be correct.

Errors appear to always be in columns 2 or 4, mostly in the middle of the screen and sometimes near the bottom, always near tile edges (Y = multiple of 8), but random in exact timing. On average one frame in 6 has a visible glitch.

I swear I remember someone complaining about something very similar to this glitch vaguely recently.
edit: this thread : https://forums.nesdev.com/viewtopic.php ... 12#p196312

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Dwedit
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Re: NES graphics issues

Post by Dwedit » Sun Jan 20, 2019 12:26 pm

I wonder if it would go away if you cleaned the motherboard with alcohol and a toothbrush?
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Fiskbit
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Re: NES graphics issues

Post by Fiskbit » Sun Jan 20, 2019 4:53 pm

When BMF54123 was testing OAM decay stuff for me recently, he was having this sort of artifact in the right half of the screen with his Everdrive, and only in the menu. If I recall correctly, a Zelda 2 runner I watch on occasion also had this sort of thing toward the top of the screen when using a specific cart, but I unfortunately can't find a video of that.

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Re: NES graphics issues

Post by Fiskbit » Mon Jan 21, 2019 4:36 am

Here's a picture of what BMF54123 was encountering on his Famicom Everdrive menu on two frontloaders. Note that he needed to use an an adapter with these, didn't have the problem on his AV Famicom, and doesn't have the problem with other Famicom carts over the same adapter.
Attachments
Everdrive short glitchy lines.jpg

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Fisher
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Re: NES graphics issues

Post by Fisher » Mon Jan 21, 2019 4:41 am

I think they're similar to this post.
The solution for that problem was to change the latch for an AHCT part.

I've heard of people changing the latch for an HC part for better compatibility, take a look on the other posts of the thread.
l_oliveira wrote: That happens with the powerpak too. People replace the PPU latch IC to attain better powerpak compatibility. It boils down to the timing, different reasons for the same problem.
Maybe this could solve your problem too?

capsulej
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Re: NES graphics issues

Post by capsulej » Wed Jan 23, 2019 7:37 pm

I seem to get the same error on both original carts and the Everdrive, so im not sure if its the same one.

Roussen
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Re: NES graphics issues

Post by Roussen » Thu Jan 31, 2019 8:00 am

Is there any way to reproduce this error? I want to check out what happens.

capsulej
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Re: NES graphics issues

Post by capsulej » Thu Jan 31, 2019 6:51 pm

what do you mean by reproduce? It never goes away. Its there the whole time for every game..

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Fisher
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Re: NES graphics issues

Post by Fisher » Fri Feb 01, 2019 7:16 am

Could you please post some pictures of your console's motherboard?
This problem is very weird!

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