NES de-jitter un-mod

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triskalguilo
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Joined: Fri Aug 31, 2018 9:08 am

NES de-jitter un-mod

Post by triskalguilo » Tue Aug 13, 2019 10:47 am

So I tried to do the NES de-jitter mod, and because I have sausage fingers and don't know when to quit poking things with a soldering iron, I ended up ruining some of the solder pads and traces on the de-jitter board :roll: I've resolved that the de-jitter board is beyond my repair capabilities, so now I just want to un-do the whole thing.

The mod involved removing C44, C45, and X1, so now I need to re-attach those. Unfortunately C44 and C45 crumbled to dust as I was removing them; I have no idea how they were labeled, so now I don't know what to replace them with. Googling gets me conflicting info. The consensus seems to be that C44 is 51pf; some say that C45 is 68pf, while others say 220pf.

Can anyone help a sausage-fingered guy out and tell me the specs for C44, C45, and X1? Bonus if you've got some Mouser or DigiKey part numbers! :D

lidnariq
Posts: 9141
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: NES de-jitter un-mod

Post by lidnariq » Tue Aug 13, 2019 11:22 am

See my fixed and annotated copy of Electronix Corp's reverse-engineered schematic: https://forums.nesdev.com/viewtopic.php ... 83#p203383

You could also look for the service manual for the 19SV111, which contains an NES inside it, and includes the only currently-known official NES schematic.

Assuming you have an NTSC NES (because the PAL NES doesn't need de-jittering), that crystal is 21.477MHz. They're a little bit harder to get.

triskalguilo
Posts: 3
Joined: Fri Aug 31, 2018 9:08 am

Re: NES de-jitter un-mod

Post by triskalguilo » Tue Aug 20, 2019 9:04 am

lidnariq wrote:See my fixed and annotated copy of Electronix Corp's reverse-engineered schematic: https://forums.nesdev.com/viewtopic.php ... 83#p203383

You could also look for the service manual for the 19SV111, which contains an NES inside it, and includes the only currently-known official NES schematic.

Assuming you have an NTSC NES (because the PAL NES doesn't need de-jittering), that crystal is 21.477MHz. They're a little bit harder to get.
Thanks for your help! :) I couldn't find one of the two capacitors labeled on your schematic (it's probably there, I just didn't see it), but -- as it turns out -- the board itself is labeled for C44 and C45 :oops: :D So, for the Googlers that end up here, C44 is indeed 51pF, and C45 is 220pF.

Interestingly, I took apart another NES for reference, and found that it had a 221pF cap in C45. I guess that extra 1pF doesn't matter to the NES :)

lidnariq
Posts: 9141
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: NES de-jitter un-mod

Post by lidnariq » Tue Aug 20, 2019 9:59 am

"221" on a capacitor does not literally mean 221! it means 22 x 10¹ pF, or 220pF.

triskalguilo
Posts: 3
Joined: Fri Aug 31, 2018 9:08 am

Re: NES de-jitter un-mod

Post by triskalguilo » Wed Aug 21, 2019 7:57 am

lidnariq wrote:"221" on a capacitor does not literally mean 221! it means 22 x 10¹ pF, or 220pF.
D'oh, you're totally right. Disregard! :)

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