Proper USB power mod for the Megadrive 2
Posted: Fri Feb 28, 2020 1:30 am
Hello guys, long time no see !
So after seeing a few people doing a USB mod to their NES, i had the idea of doing the same to the Megadrive.
Of course as you may know, the 7805 regulator outputs 5V, just like the USB standard, hence why i decided to apply the same mod to it.
I managed to make it work and also reduced the noise by adding a few caps to the 5V line (one 0.1uf cap, another 1uf and the last one 10uf).
(It looks really nasty, i will clean it up and shorten the wires after my issue is solved)
Basically the 5V line goes to one of the power switch pins first then goes directly to the output pin that was formerly used by the 7805.
So far i loved it, the power consumption is much improved and there's less noise & inteference visible on the screen with the French Sega SCART cable.
...That is until i realized one minor issue with my Mega CD. (so far the Mega CD has not been touched)
It powers on just fine but when you power it off (via the power switch), the Megadrive powers off but the Mega CD is still powered on and still plays the CDDA track !
I have no idea how it is supposed to know how to be turned off or anything and looking at the schematics did not enlighten me either.
I'm sure there's something wrong with my mod, so is there a better way of doing the mod ? (without using the power button pins for example)
Thanks
EDIT: I fixed it, it was kind of dumb. See my posts below.
So after seeing a few people doing a USB mod to their NES, i had the idea of doing the same to the Megadrive.
Of course as you may know, the 7805 regulator outputs 5V, just like the USB standard, hence why i decided to apply the same mod to it.
I managed to make it work and also reduced the noise by adding a few caps to the 5V line (one 0.1uf cap, another 1uf and the last one 10uf).
(It looks really nasty, i will clean it up and shorten the wires after my issue is solved)
Basically the 5V line goes to one of the power switch pins first then goes directly to the output pin that was formerly used by the 7805.
So far i loved it, the power consumption is much improved and there's less noise & inteference visible on the screen with the French Sega SCART cable.
...That is until i realized one minor issue with my Mega CD. (so far the Mega CD has not been touched)
It powers on just fine but when you power it off (via the power switch), the Megadrive powers off but the Mega CD is still powered on and still plays the CDDA track !
I have no idea how it is supposed to know how to be turned off or anything and looking at the schematics did not enlighten me either.
I'm sure there's something wrong with my mod, so is there a better way of doing the mod ? (without using the power button pins for example)
Thanks
EDIT: I fixed it, it was kind of dumb. See my posts below.