How to Overclock the SEGA Master System from 3.5 MHz to 4.434 MHz
How to improve the speed of the SEGA Master System by overclocking from 3.5 MHz to 4.4 MHz.
Eliminate flickering and see the games much more fluid.
We all know that one of the weaknesses of the Master System was that it was on the market for many years and shared the stage with the next generation consoles of the time. In fact it was easy in the 90s to find the same titles on Megadrive as well on the Master System, the second one logically with cuts due to the reduced power of the hardware.
One of the problems of the SEGA Megadrive "ports" was that for the Master System games some times where not finished, were working not correctly, had slowdowns, flickering and control failures. This happened not only with the ported games, but it also happened with some exclusive titles for the Master System console.
After years of trying to find a solution to all these problems I couldn't believe that no one anywhere found a solution and posted it on the internet. About 3 months ago I saw on YouTube a video from my colleague MinaseTakix showing a Master System at 4.434 MHz working correctly. I was able to talk to him and from there make the "mod" and publish it here so that we can all benefit.
Before starting:
- We are not responsible for how your console will look after the modification, it is an easy modification, but you can make it completely unusable if you do it incorrectly.
- This "Mod" is NOT 100% stable, there are some games that are not compatible and others in which gliches may appear but by putting a switch to be able to choose between the original frequency and the overclocked one we can solve it.
Items needed for modification:
- First of all a soldering iron, I recommend a "decent" one since we are going to do some welding with relative precision (the one we use in this "mod" is a "26w JBC 40S")
- Tin
- Flux (In this case it is optional, it is always recommended to use flux to make welds of this type, but I did not have it at the time of doing it)
- 1 Two-circuit switch (In this case it is to be able to choose between the 3.5 MHz serial frequency and the 4.434 MHz overclock)
- A couple of meters of very thin cable
- Logically a Maser System I or Master System II (Not compatible with III)
We open the console, it's a few screws. The next thing we need to do is identify the "chips" involved in the process:
The first and most important is the CPU, which in the case of the Master System is a Z80 from Zilog.
We will identify it because it is a large elongated chip on which it says "ZILOG Z80 CPU".
The second and no less important is the chip "SEGA 315-5237" in this case it is also an elongated chip in which it puts the name of the chip above "SEGA 315-5237" the chip is similar to this:
Technical data
What we need to know is that the Zilog's Z80 (that is the CPU) acquires the value of the frequency from the pin number 6.
The chip "SEGA-315-5237" through pin 42 outputs a frequency of 4.434 MHz referring to RGBCLK (OSC/12, 4.434 MHz).
What we will have to do is the following:
1 - Once we identify the ZILOG Z80 Processor we look for pin number 6. Once located we cut it in half. I used pliers, but you can try with scissors. This step is critical, and if we do not do it well the console is literally dead. It is VERY important that there is a piece of the pin on the console board and another piece on the Processor, since otherwise you will not be able to do the soldering correctly.
2 - Once cut we have to solder two cables, one to the part that remains of the pin on the plate and the other to the part that remains on the processor.
The result should be like in the following photo:
The red cable is the one that corresponds to the source frequency and the yellow cable is the one that has to receive a frequency.
3 - We locate the "SEGA 315-5237" chip and WITHOUT cutting anything on pin number 42 we solder a cable to it.
Result:
This other yellow cable is the one that will give us the speed at 4.434 MHz.
4 - The next and penultimate step we have to solder the other ends of the cable to the two-circuit switch.
Result:
In this case, at the ends are the cables that come from the motherboard of the console and the SEGA 315-5237 chip that give us the speed, either 3.5 MHz or 4.434 MHz
5 - Finally we have to find a good location for the switch, in this case the final result was as follows:
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