PSTwo Power Problem Solved... (Finally)

segasonicfan · Post by **segasonicfan** » Mon Jul 11, 2005 2:41 am

Some great news for PSTwo Portable builders out there: You CAN run the whole system+screen+speakers etc. off one battery! As some of you may know I had been using two batteries for my PSTwo for a while due to consumption rates and interference using one battery for the PSOne screen and PSTwo system. The solution was actually somewhat simple:

To make a necessary battery I needed more than 8.5v to run the system but 7.5-8v to run the screen. However, Li-ion cells are 3.6v~4.2v per cell so I would have to use 3 cells to get the nominal voltage up to ~12.1v The PSTwo WILL run on this! Then I simply tapped that into a 7808 voltage regulator for the screen.

Now, the biggest problem after that was the interference. When a disc begans spinning and the system begins reading it the picture quality went to crap. So I put on a couple large uf caps to clean up the power line and the result is a VAST improvement in quality. And that's it! You just need a 4-6amp li-ion 12.1v battery and you are good to go. Of course I put in a couple DPDT switches to ensure that I could use both power supplies again if I wanted to.

Additionally, you can use this (minus the 7808) to run your system+screen of the original PSTwo power supply. Since it outputs a tremendous and unecessary 5.65 amps, you can wire your screen directly to the supply and put on the caps to clean up the power line. I also installed an extra cooling fan on my PSTwo and I can get everything running off the original power supply. Pretty nice!

-Segasonicfan

elixirnova · Post by **elixirnova** » Thu Jul 21, 2005 7:36 am

Ya know itd be pretty nifty if there was a diagram(cough cough) of the circuit

. And so is it better to run the pstwo off more than 8.5V, and is 12.1 really good for the voltage?

usbcd36 · Post by **usbcd36** » Thu Jul 21, 2005 12:49 pm

Is there a regulator that will go from 12.1v (or less) to 8.5? If so, you could use that to input the correct voltage.

segasonicfan · Post by **segasonicfan** » Thu Jul 21, 2005 2:30 pm

well the input runs through some caps and inductors but eventually leads to two 7805 LDO regulators. From here it leads to a large 3A output 3.3v regulator which i believe powers the entire system. However, the system will not run off 8.3v or less. this leaves me to believe something does require the full voltage other than the 7805s (because they usually only have a 2v dropout range). It's possible the fan (which runs off 8.5v) is the only thing that uses the main power supply voltage. The system will not start without the fan starting (it has a detector line like in PCs). So you don't need the full 12.1v and there isn't any real advantage to it unfortunately. However, li-ion cells only come in 3.7v so you're either going to hav e 7.4v (too less) or 12.1v (which will run but is a little too much). Ideally, I'd like to use one expensive 7805 regulator with high current output in a TO-220 package. This would reduce the heat dissipation. And then I could simply run that to the 7805 lines on the PSOne screen adn power the whole thing with a high-amp 7.4v li-ion battery pack and have one extra cell for the fan.

Of course, that's not going to happen cause I don't feel like opening my PSTwo again and risk breaking it once more. Plus, I have my doubts that even that would work. It's possible the power lines run to additional places, it's hard to tell on a tri-board PCB. Anyway, I'll put a diagram and pics up of the power supply I'm using now on my site very soon.

As for the full power, I found Ben was wrong with his readings. It does not draw an average of 2amps, it's closer to 2.7amps but conservitavely ocsillates just under 3amps. So running the system and the screen you're looking at around a 3.7amp draw...that's a lot! I had to make a rather large 12 cell li-ion pack for my system to get any decent amount of time. I ran it for about 2 and a half hours FULL power with the additional cooling fan (that takes around 4w). But that's using speakers, full brightness, and an extra fan. Just keep in mind this portable sucks a lot of juice.

-Segasonicfan

usbcd36 · Post by **usbcd36** » Thu Jul 21, 2005 2:57 pm

Wait, what is the number on that 3.3v regulator? People over at the N64 section need that thing like mad! I need that regulator like mad!

elixirnova · Post by **elixirnova** » Fri Jul 22, 2005 8:10 am

So ideally If I one could find 6Ah+ 7.2V pack and run it through two 7805's and then make it 10Ah the pstwo could run off that and if I could get my hands on a 3.3V regulator you speak of a 3.3V regulator could be ran with a 7805 and create 8.3V for the screen? Isn't some amps lost through voltage regulation though? Because if so all the voltage regulators are going to be wasting usefull power on this 3amp+ sucker.

Btw: I remember reading it actually boots up on around 2Amps and slow disk speed is around 2.6-2.7Amps and high disk speeds can go around 3Amps+ though high disk speeds arnt held for long...