Hey guys, I'm back without another one of my Dreamcast mods. This time it is an overclock of the Dreamcast system and the VMU to match. VMU needs to be overclocked to match the Dreamcast new speed. Otherwise corrupt game saves will be encountered. Recommend you back up your game saves first before attempting this.
Note: I am not responsible, nor Acidmods, for any damages you do to your Dreamcast or yourself should you follow this guide I had set up.
Dissembling the Dreamcast is very easy so I won't upload any pictures of that. Basically, remove the screws on the bottom and remove the top half cover. Then unscrew power supply, GD-Rom lens, and controller port. Followed by the heatsink/metal shield. Voila! Easy peasy.
Dreamcast VA2 Motherboard:
Pin 1 = NC(no connection)
Pin 2 = GND
Pin 3 = Output to Dreamcast points A or B
Pin 4 = VCC
The area is just below the power supply pins. The oscillator frequency is 40MHz. Also, there is a jumper resistor labeled at R331 that connects the PLL chip to the Dreamcast SH4 chip. Remove this jumper resistor, otherwise, you can do it the hard way and try to lift the legs of the PLL chip. I find removing the jumper is easier and if I wanted to go back to stock, then I would just solder the 2 points together with a solder bridge or lead wire.
Once finished, the Dreamcast will now run at 240MHz vs the stock 200MHz. For me, I noticed a difference when playing 3 games. Tokyo Xtreme Racer 2, Skies of Arcadia and Grandia 2.
TXR 2 is known to lag/stutter when a race is about to start or when the replay is being viewed. This is especially the case with backups and rips. The original disc has some stuttering as well but not as much. I have both the original disc and a ripped copy and the ripped version plays flawlessly. I have no doubt that the original will also play without stuttering.
A few Grandia 2 rips also stutter consistently as well. I have Taiyo Yuden CD-Rs and I burn at various speeds and all rips stutter and skips at the same position. But with the overclock, all the rips runs very smooth! My original disc is being delivered today so I will be playing it this weekend.
And then there was Skies..... Well if you played this on the Dreamcast then you should know what happens, LMAO. I'll keep it short and say the above results will be the same here.
And now the VMU overclock:
Remove old crystal first
New Crystal
Remove the battery cover and batteries by removing the screw on the back of the VMU.
Then remove the 4 screws in the corners.
Carefully separate the back cover as the speaker is glued to it and the wires are soldered to the PCB.Remove the 6MHz crystal and replace with the new crystal.
I used an 8MHz crystal from Mouser. Will link to it if it is allowed. Minimum value needed is 7.2Mhz if you are overclocking the Dreamcast to 240MHz. But the VMU can be used if it is overclocked a bit higher than the Dreamcast.
That's it! Enjoy!
Edit:
These Dreamcast Revision are running stable @240mhz
Dreamcast VA0
Dreamcast VA1
Dreamcast VA2 (Before November 2000 manufacture date And some November 2000 dated VA2 board) (Mine is a October 2000 revision)
This one is not so stable
Dreamcast VA2 (After November 2000 date - Not stable try a lower frequency- Don't have one to try though so I can
t confirm)