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PostPosted: Tue Apr 11, 2017 12:48 pm 
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I just got a used NES but when I boot it up I noticed that there were green outlines everywhere and a green bar across the middle of the screen. Has anyone ever seen this?


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PostPosted: Tue Apr 11, 2017 12:55 pm 
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Pictures please.


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PostPosted: Tue Apr 11, 2017 1:52 pm 
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Sorry for the late reply, here are the pictures


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File comment: It's also on Battle of Olympus, This is a picture of the green stripe (it's more obvious on this game)
IMG_20170411_165106_1.jpg
IMG_20170411_165106_1.jpg [ 57.77 KiB | Viewed 1306 times ]
File comment: There is a green outline on Mario (This is SMB Duck Hunt if that makes a difference)
IMG_20170411_164713_1.jpg
IMG_20170411_164713_1.jpg [ 64.12 KiB | Viewed 1306 times ]
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PostPosted: Tue Apr 11, 2017 2:15 pm 
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That green bar has been seen before, some kind of shadow image of horizontal blanking. I can't remember if there was a solution for this, but there was definitely a thread about it before (but I can't find it at the moment).

As for outlines on Mario I'm not sure what that's a picture of but it's normal/standard for the NES to have colour errors at the edges of shapes due to how it generates its NTSC signal (example).


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PostPosted: Tue Apr 11, 2017 2:18 pm 
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I noticed that when I do anything it gets mirrored on the other side of the screen in that same green


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PostPosted: Tue Apr 11, 2017 2:22 pm 
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Would the horizontal blanking interval be due to the up scaling? Could it be due to the TV itself? I am using an adapter to convert it to HDMI but it works perfectly on the ATARI.


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PostPosted: Tue Apr 11, 2017 2:26 pm 
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As you can see the blocks are being mirrored to the left, thi bugs me the most


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PostPosted: Tue Apr 11, 2017 2:37 pm 
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Interesting. It looks like those are off by 128 pixels. Maybe some counter in the PPU's 8th bit is broken, and something funny inside there is actually affecting tile fetching. That is going out on a limb considerably, though.

Do you have another TV to try?


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PostPosted: Tue Apr 11, 2017 2:39 pm 
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Jackknife18846 wrote:
As you can see the blocks are being mirrored to the left, thi bugs me the most

Oh wow, maybe that's not the problem I'm thinking off.

mikejmoffitt wrote:
Interesting. It looks like those are off by 128 pixels. Maybe some counter in the PPU's 8th bit is broken, and something funny inside there is actually affecting tile fetching. That is going out on a limb considerably, though.

I would guess this is some sort of analog signal delay, not any kind of logical failure in the PPU. I think a logic problem would have much stronger consequences than an afterimage kinda thing like this.


Last edited by rainwarrior on Tue Apr 11, 2017 2:41 pm, edited 1 time in total.

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PostPosted: Tue Apr 11, 2017 2:41 pm 
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Jackknife18846 wrote:
I am using an adapter to convert it to HDMI but it works perfectly on the ATARI.


Does it do anything like this without the upscaler? If not, whatever adapter you're using should be the prime suspect.

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If you're gonna play the Game Boy, you gotta learn to play it right. -Kenny Rogers


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PostPosted: Tue Apr 11, 2017 2:43 pm 
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I have a portable sreen to try acually but not a CRT or anything


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PostPosted: Tue Apr 11, 2017 2:46 pm 
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I just replaced the TV with AV support before I got the NES, I can only try it with the adapter


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PostPosted: Tue Apr 11, 2017 2:46 pm 
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You appear to have a "reflection" in the video output. The easiest things to try first depend on how you're connecting to the TV right now: if you're using the RF output, try another RF switch; If the RCA output, try another (different length) RCA cable.

The green vertical bar is how the TV signal specifies the hue of the color information on screen, repeated somewhere around 1/3 to 1/2 of a scanline (≈20 to 30µs) later. This can be caused by the TV lacking the correct input impedance, the NES having the wrong output impedance, or the cable being damaged.

(I wouldn't be the least bit surprised if a cheap composite-to-HDMI converter had the wrong input impedance)


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PostPosted: Tue Apr 11, 2017 2:50 pm 
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I'm pretty sure the adapter is the problem. It does work on my ATARI though.


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PostPosted: Tue Apr 11, 2017 2:52 pm 
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The adapter needs to be plugged in but I haven't tried it unplugged. I'll see if that fixes it.


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