Help dual crystal oscillators PAL/NTSC PU-8 (colour fix)
Posted: August 30th, 2024, 11:28 pm
Hello everyone.
Some time ago I modified a sega megadrive to run at 60Hz with proper NTSC timings by replacing the crystal, and I now want to do the same thing with my playstation.
I still have a spare 53.69Hz crystal, because I got two when I wanted one for my megadrive.
It is a lot bigger than the one found in a playstation, but I don't think that matters.
I found two threads that kind of show how to do what I want, but not exactly.
Here someone shows how to move parts from an NTSC PU-7 to a PAL PU-8:
https://www.psxdev.net/forum/viewtopic.php?f=47&t=628
And here someone shows how to "replace" the crystal on a PU-23 with a bigger one:
https://www.psxdev.net/forum/viewtopic.php?t=3554
My PU-8 has pads for a 2nd crystal.
From what I understand, I need to remove a 0 ohm resistor on the back of the board. Get a 220 ohm resistor to put between the trace going to the GPU and one of the legs to the crystal. But I also need a capacitor of which I don't know the amount of uF, and what are the specifications for the RF choke?
I don't have tweezers, so I can't solder very small components.
So my question is, what are the values for the capacitor and RF choke?
Also, it looks like the pin on the opposite side of ground on the crystal needs to lead to a 220 ohm resistor and a capacitor on the other side of the board. The capacitor on the other side of the board would be connected to ground.
Does it matter where it connects to ground? It seems easier just to bridge the pads for the resistor and solder a capacitor to the pad for the crystal opposite of ground and solder the other end of the capacitor to ground, then solder the 220 ohm resistor to the same pad with the other end soldered to the pin on the crystal. Would that work? I'm not very familiar with electronics yet.
I've made some pictures to illustrate my idea, no idea if it would work. (and it of course lacks some components, because I don't know what I need to add)
The pictures are not of the board I'm going to install this on, but from a broken board I have.
My other console has the same board though.
Some time ago I modified a sega megadrive to run at 60Hz with proper NTSC timings by replacing the crystal, and I now want to do the same thing with my playstation.
I still have a spare 53.69Hz crystal, because I got two when I wanted one for my megadrive.
It is a lot bigger than the one found in a playstation, but I don't think that matters.
I found two threads that kind of show how to do what I want, but not exactly.
Here someone shows how to move parts from an NTSC PU-7 to a PAL PU-8:
https://www.psxdev.net/forum/viewtopic.php?f=47&t=628
And here someone shows how to "replace" the crystal on a PU-23 with a bigger one:
https://www.psxdev.net/forum/viewtopic.php?t=3554
My PU-8 has pads for a 2nd crystal.
From what I understand, I need to remove a 0 ohm resistor on the back of the board. Get a 220 ohm resistor to put between the trace going to the GPU and one of the legs to the crystal. But I also need a capacitor of which I don't know the amount of uF, and what are the specifications for the RF choke?
I don't have tweezers, so I can't solder very small components.
So my question is, what are the values for the capacitor and RF choke?
Also, it looks like the pin on the opposite side of ground on the crystal needs to lead to a 220 ohm resistor and a capacitor on the other side of the board. The capacitor on the other side of the board would be connected to ground.
Does it matter where it connects to ground? It seems easier just to bridge the pads for the resistor and solder a capacitor to the pad for the crystal opposite of ground and solder the other end of the capacitor to ground, then solder the 220 ohm resistor to the same pad with the other end soldered to the pin on the crystal. Would that work? I'm not very familiar with electronics yet.
I've made some pictures to illustrate my idea, no idea if it would work. (and it of course lacks some components, because I don't know what I need to add)
The pictures are not of the board I'm going to install this on, but from a broken board I have.
My other console has the same board though.