Replacing the DC PSU

http://www.ebay.co.uk/ulk/itm/191219607772

 

Excellent - thanks!

 

Can I just install another 12 volt fan to draw the power off the psu to cool it down? If so how many amps or watts should the fan use to make the additional fan useful?

 

No, a 12v fan does nothing to bring the +12v down from what I've found. It only makes the fan spin like crazy because its getting something like 13.9 volts

 

So does that mean that the GD Rom drive also suffers from this voltage spike when it's in use?

 

No, as the reason for the spike it that it's not using it at all.

 

thanks for the response.

I see some people connecting the 12V coming in to the dreamcast power switch circuit. What advantage does this give as opposed to just connecting the switch to PS_ON & GND on the pico?

 

None really. But for me, it gives me the comfort in knowing that no power goes into the Dreamcast PSU when its off =)

 

Before I do this - is this what we want? Just short the PS_ON and connect the 12V in to the dreamcast switch (via the gray wires).

 

Yep, that's what you want.

I tried using PS_ON at the power switch at first but ended up with weirdness like the console not turning off properly and voltage staying present on the output of the PSU. So don't do that...

 

Ok I have been having some strange behaviour with my DC & the PicoPSU.

When playing some games the audio will start slowing down or sound crackly.

It's either the PicoPSU or the power supply I'm using that is causing the issue, as replacing the PSU with the original (with the 12v rail disabled) fixes the issues.

Games I had issues with.
Dead or alive 2 has the audio issue. (Start a sparing match & wait a few seconds)
Who wants to beat up a millionaire has audio issues. (Playing the game as normal)
Virtua tennis 2 has audio issues. (Playing the game as normal)

It's weird as I have only noticed it happening recently maybe my power brick is on its way out.

 

Hello everyone, I've read this entire thread and can make some sense of it but not 100%. I'd like to install a Pico PSU, and would of course like to avoid as many of the audio / sound problems etc as described variously. This is my setup...

PAL DC model 2 (the more common or garden variety DC) with multi region BIOS mod.
GDEmu board.
Toro VGA out box.

I can solder a bit and follow a clear guide, the trickiest job I have tackled was switch region modding an MDII; I would greatly appreciate an idiot guide to this. The 12v rail and 3.3 and 5v stuff is particularly confusing to me.

Many thanks, and kudos to all involved.

My other idea is to remove the existing PSU and convert it to a power brick in a well vented box, is that really stupid, or viable?

 

What I have went back to is using the default PSU (12v rail removed) but with a fan positioned on top of the UGC & it running at 3.3v. (same as the small outtake fan, yes I run it at 3.3v) I'm doing it this way until I can be bothered/get a new power brick that is at least 5A.

The DC will run the small fan at 3.3v fine & not complain, even if using the stock PSU, but the stock PSU will get very hot if running the fan at this voltage, so I only recommend it if using a Pico, or you add a fan like I done, keeps the PSU cool.

& your idea would work, you could run a small fan at 3.3v to cool the PSU inside the box, the issue is making it look nice

 

A picoPSU with a good quality power brick works like a charm with minimal heat. Just follow the diagram posted a few posts up for the power, and connect the PSU 3.3 and 5 volts to the dreamcast respective inputs. Personally I've connected the 12v too, but it shouldn't be required.

 

Thankyou both, I appreciate the input. I looked at the diagram, I take it that it refers to the pins / points (technical terms - aarrrgh!) on the PSU? I take it I would solder / attach these points with wires to the corresponding pins that come off the DC's mobo?

 

Yes pretty much. The diagram up here shows only how to power up the PSU, independently from the Dreamcast.

There's 3 other pins you need to connect to pet up the Dreamcast, the three voltages, though the 12v can be omitted.

 

Thankyou, I have another question... Having read about strange behaviours related to the PSU I'm keen to keep the existing unit, having made a plastic shield to mimic the position of the old GDROM assembly the airflow seems to running well insofar as the air escaping is warm. I also swapped out the PSU like for like with my disc reading DC which seems to run a little cooler.

What exactly does 'disabling the 12v rail (what is a rail?!)' mean, and will this make the system run cooler?

 

Anyone know the original part number of the PSU connector?

 

http://atariage.com/forums/topic/236202-fs-usb-gdrom-dreamcast-mods-service/page-2

There's a post on this board about 'jamming in' a resistor between the 12v rail and ground. Would this help, and where are these two locations? Sorry for all this spam, but I really am a noob with this stuff.

 

If you already got a picoPSU, use it. It's much better than the original one, doesn't produce much heat, and doesn't induce any noise as long as you use a good and stable 12v power supply for it.