Overclock NES?

[Talasonic]

I thought it would be cool to overclock it to make TMNT Arcade work a lot better and other games.  Like, maybe it would fix slowdown.  So has anybody tried this?  

[Richter X]

The only way you can overclock the NES is to swap out the crystal.

[Guest]

Sounds good.  Do you know of directions somewhere?  I looked a little bit.  If you know where it is, that would help me.  Thanks!

[dum dum]

i havent looked into a nes for a while, but assuming its just got the one main clock that gets devided for all other timings, then changing that would change all timings..

for example if you doubled the speed of the main crystal, then your nes would try to double the speeds of the video (120Hz vertical refresh, 30KHz horizontal, broken ntsc subcarrier etc) and the audio would be twice as fast and an octive higher - the ram might not be fast enough for the system and the gameplay would run twice as fast assuimg the cpu doesnt blow up. so expect general dodgyness and possible system lobotimization.

maybe if you changed the speed of the cpu but provided normal clock signals for the video/audio systems etc it might work but i dont know if anyones tried, it might just all be a theoretical pipe dream?

[phreak97]

this sounds interesting.. i have a pal nes, it runs 16.6% slower than an ntsc system in all gameplay, this i dont like.. are you saying if i got a crystal 16.6% faster than the current one, it would output 60hz video and speed up the whole thing to the propper speed?

the H-sync changing sounds bad tho.. could that make the whole thing impossible to do?

[Talasonic]

Phreak--I think that would probably work, if you have a multi-system TV.  

But, I don't know.  I was hoping it had more than one clock chip.  I am not after faster gameplay, just smoother gameplay.  Basically I'm looking for a speed increase like that of a computer.  It makes the game play better, not faster.  

However, if the PAL NES is slower than the NTSC NES, like Phreak says, that would tend to corroborate what dum dum says.  After all, it's hard to believe that Nintendo would have slowed down the PAL release unless they had to.  And having only one clock chip seems like the only reason they would have had to.  And 30-16.6666%=25, too (NTSC standard is  about 30fps, PAL 25fps).  

So I guess my hopes of overclocking the NES are dashed.  But at least Phreak might now be able to fix his NES.  

Anyway, next time I open my NES, I'll look for the clock chip(s) and see if there is just one.  

[phreak97]

i have tried researching online with very few results on crystals.

the crystal (X1) in my nes has the following printed on it:

26.601712
 KDS 9L

it has a pot connected to it with a small cap accross the pot.
i have never had to read the values of a crystal before. (sorry lawrence if i am asking too many questions, i probably am)

is the 26.60... mhz or hz or just a part number?
and is it a bad idea to adjust the pot?

this question could solve everything and make the others useless: anyone know if the ntsc crystal has a diff value and if so what is it?

(sorry again lawrence:P i did learn my lesson and researched over an hour with no result that would tell me anything of use to me)

[Talasonic]

21.47727
KDS 7G

That's what is in my NTSC North American NES.  

That's SLOWER than yours!  

Perhaps there is another clock chip in the RF box.  I may remove that soon to see what's in there.  

In the mean time, Phreak, you might consider changing your crystal to be 6% faster.  

PAL: 25.00fps
NTSC: 29.97fps

25.00 = 29.97
26.601712 = x

x=29.97*26.601712/25
x=31.8901323456

So you could try a crystal close to 31.8901323456.  

Or, you could try opening the RF box to see if there is another crystal in there, although I'm not sure how that would help you.  

[dum dum]

pal composite video subcarrier frequency is about 4.43361875 MHz, NTSC is about 3.579545 MHz - thats 1/6th of those main crystals you guys have mentioned.  so then that means if you were to change that crystal your colours would break, but maybe if you solved that problem (get a 2nd 4.43/3.57Mhz crystal just for the video out parts) you might keep colours but this is pure speculation on my part

[phreak97]

by "break" do you mean it just wont work while the new crystal is in or will it do permanant damage to the nes's video? and why is it you can replace a chip in a nes to change it to an ntsc console from a pal one without changing the crystal? wouldnt the pal crystal be incompatable with the ntsc chip if your theory is correct?

basically, ill try it all if im not going to break my nes with the 6% and 16.6666% faster crystals, im desperate.. im sick of the slow nes. also buying an ntsc nes is not an option for me atm.

[Talasonic]

I have an extra NTSC NES.  Would you like to trade, phreak?  I'd be kind of interested in comparing your PAL to my NTSC.  I don't know what shipping would be.  I'm in Virginia, USA.  Looking on ebay, it looks like a PAL NES is worth more than an NTSC NES, which is weird.  I can throw a US Mario 1 or something in with mine if you want.  Actually, I'd also like a PAL game to do testing with, if you can spare one.  

I assume it's easy to defeat the region protection?  I haven't done anything to the NES in question.  Or, I can give you my other one that I put stereo output on.