NES Overclocking Alteretive to Epic gameings OC guide

Jongamer · Post by **Jongamer** » Fri Feb 16, 2007 6:38 pm

Ok While salvageing parts out of a bad GG, I found a Crystal that is faster than the NES clock by a few Mhz, so could I take the 24 Mhz crystal off the NES board and get a faster Clock speed? or is this Crystal for something else on the NES's Mobo?

TheOnlyOneHeFears · Post by **TheOnlyOneHeFears** » Mon Feb 19, 2007 11:48 am

A difference of a few Mhz won't make much difference. To get the clock speed, the NES divides the crystal value by 12. It depends on how much more Mhz the crystal has.
My advice would be to follow the guide on Epic Gaming. I'm planning to do this too, if I can find crystals in the UK

Jongamer · Post by **Jongamer** » Mon Feb 19, 2007 11:57 am

TheOnlyOneHeFears wrote:A difference of a few Mhz won't make much difference. To get the clock speed, the NES divides the crystal value by 12. It depends on how much more Mhz the crystal has.
My advice would be to follow the guide on Epic Gaming. I'm planning to do this too, if I can find crystals in the UK

yeah I did their guide before, but Its pretty hard to find a good place to put the Crystal once its in there, and when I used the Reccommended Crystal mhz I got nothing but scrambled Graphics but it did work, and then when I put a Lower Mhz crystal oscilator, the NES died, all I got was a Fizzle on the TV screen.

TheOnlyOneHeFears · Post by **TheOnlyOneHeFears** » Mon Feb 19, 2007 12:42 pm

Ouch, sounds like you had a rough time there! It says it might not work on some NESs, but that still sucks. Does the NES still work if you use the original crystal?

Epicenter · Post by **Epicenter** » Wed Mar 21, 2007 1:40 am

The reason my guide mentions using a 4-pin Crystal Oscillator tied directly to the CPU clock input pin is that replacing the crystal on the board will change the system clock, which WILL change the CPU speed, but also the rate at which the entire machine operates. It will even change the reference frequency for the PPU's video hardware, resulting in a video signal that is useless to a standard TV, and if you did manage to coax a picture out of the machine, the games would run faster than they are supposed to.

Replacing the CPU's clock signal and nothing else means that the only unwanted effect is a rise in audio pitch and some occasional minor glitches involving memory mappers.

As far as placing the oscillator-- you can glue it to any plastic part of the case if you like, or use my preferred solution-- find a bare part of the PCB, and stick the oscillator there-- Text side down, Pin side up, with some double-stick mounting tape, the sort you use to attach heavier things to walls like coat hooks.

While the disclaimer is that the modification won't work on every NES-- you should be able to coax at least 0.3 MHz or so out of any system. Just don't count on terrific results everytime. I got my machine to 4.2 MHz, which is over 230% normal speed-- don't expect to get as lucky as I did!

Tips to maximize your overclock:
- Use a stable clock generator.
- Use short thin cables. I like to use shredded-up PC IDE cables, the sort used for hard drives and CD-ROMs and the like. Try to keep the path from the clock oscillator to the CPU shorter than a foot if you possibly can.
- Be sure to reinstall the RF shielding. It blocks unwanted EMI that can corrode your clock signal and promote instability.
- Use a power brick that supplies more current. Do not use a brick that supplies more voltage. And make sure it is the right polarity, or you may blow up the 7805 power regulator inside the unit. No one wants that.
- If your RP2A03 runs 'hot' you could put a small heatsink on it. This is extremely unlikely, however.