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NES graphics issues

NES graphics issues
by on (#232529)
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
Re: NES graphics issues
by on (#232538)
Yep. It's a PPU hardware error in every NES. More info here:

https://forums.nesdev.com/viewtopic.php?f=2&t=10104&start=30

EDIT: Nevermind. This glitch is not that glitch. Carry on.
Re: NES graphics issues
by on (#232540)
This glitch is not that glitch.
Re: NES graphics issues
by on (#232559)
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. :-(
Re: NES graphics issues
by on (#232562)
I didn't see any vertical lines, the glitches looked pretty horizontal to me.
Re: NES graphics issues
by on (#232566)
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?
Re: NES graphics issues
by on (#232568)
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 : viewtopic.php?p=196312#p196312
Re: NES graphics issues
by on (#232570)
I wonder if it would go away if you cleaned the motherboard with alcohol and a toothbrush?
Re: NES graphics issues
by on (#232578)
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.
Re: NES graphics issues
by on (#232594)
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.
Re: NES graphics issues
by on (#232595)
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?
Re: NES graphics issues
by on (#232742)
I seem to get the same error on both original carts and the Everdrive, so im not sure if its the same one.
Re: NES graphics issues
by on (#233310)
Is there any way to reproduce this error? I want to check out what happens.
Re: NES graphics issues
by on (#233361)
what do you mean by reproduce? It never goes away. Its there the whole time for every game..
Re: NES graphics issues
by on (#233393)
Could you please post some pictures of your console's motherboard?
This problem is very weird!
Re: NES graphics issues
by on (#234007)
What part did you want to see specifically?

https://imgur.com/a/CTmBKdl
Re: NES graphics issues
by on (#234041)
Oh, you've got a oldschool modded NES! We don't actually know what's going on inside the older versions of the PPU, which includes the 2C03. Other than "some bugs"...
Re: NES graphics issues
by on (#234080)
I sure hope it isn't the PPU, they aren't exactly easy to come by.
Re: NES graphics issues
by on (#234085)
Do you recall if they've always been there, or if it's a recent change?
Re: NES graphics issues
by on (#234149)
Not sure, i dont use it much. I dont remember seeing it before though.
Re: NES graphics issues
by on (#234152)
If you're up for trying something random, you could try the cheap option of replacing the 74'373 that the PPU uses. But I have no idea if it's related; it's just one thing that could possibly maybe cause the symptom you're seeing.
Re: NES graphics issues
by on (#234726)
May be completely unrelated. I was getting a glitch similar to this when using my Everdrive. I deleted the rom on which the glitch was happening and re-copied it onto the SD card. it seems fine now. I don't know whether that's helpful information or not.