Replacing the DC PSU

It's(almost) always a good practice to leave the ground connected. Put the switch on the 12v (white I think) wire.

I'm also connect in an always on scheme with a switch on the main 12v. Maybe when PS_ON is off a motherboard can still use some current?

 

A PC keeps a little current for things like wake on lan?

 

I recently picked up some knockoff picopsu from aliexpress, and a cheapo power supply. Shoved them in the dreamcast, seem to work great!

http://www.aliexpress.com/item/Z2-A...-DC-ATX-power-supply-PICO-BOX/1752404033.html - $14
http://www.aliexpress.com/item/Lowe...LED-Power-Supply-Charger-for/32234554648.html - $6

I salvaged a figure-8 socket out of another DC PSU and tried to drill out a hole for the plug that came with the picopsu, but it was too big and the socket broke in half. Had to plastic-epoxy it back together, but it looks fairly passable now. Will try to attach a pic later.

 

aaand we're back

I ended up fixing the issue by wiring the switch to the 12v input, it turns on/off instantly and no weirdness occurs.
Should've done that from the start.

 

I tried having a look at this. On the 837-13774 (the schematics posted earlier is a 837-13570), I fail to find a Q2 and R16..
There is a Q201 but no resistor called R16 anywhere. Everything seems marked differently =(

Can't find any schematics for 837-13774.

 

Gave up on trying to mod the original PSU and got a PicoPSU instead.

Everything is detachable. I used the original PSU plastic and some double sided tape on the PicoPSU to fit it in place.
Cut some metal plate for the back. Turned out OK for being the first time I did something like that. Since I made the tabs on the inside for it, there is no way its coming out. It also fits into the frame perfectly, so there is no way its going in either. Perfect and no silly glue!

This is in preparation for my next USB-GDRom to arrive. Hence the old GDi-Rom is still installed.

 

I'll keep spamming...

I bought 4 PicoPSUs so this is Dreamcast number 2. This time I tried to make it a little bit better looking.
I connected the powerswitch to the incoming 12v line this time instead of having it short green/ground like I did on the first one. Both methods work just fine. If you connect the powerswitch to the incoming 12v though, you should short green to ground on the PicoPSU or it wont turn on when it gets 12v.











As you can see, I desoldered the power connector from the PicoPSU so I could solder directly to it. I cut one of the desoldered power connectors into four parts using a thin metal saw. This is what I soldered the power into and fit on the existing motherboard connectors as you can see in the images above. The pitch is not 100% but its closer to 95% and since they flex a bit sideways, there was no problems fitting it.

The black tape is not electrical tape. Its stretch rubber for gardening and similar =) Its great. You stretch it a bit and it sticks to itself like rubber. Excellent for the power connector so you can get a nice grip on it to unplug it. It also insulates of course.

One thing though. In the pictures above you can see the power cables sticking straight up from it. I could not close the case that way. It was missing about 5mm, so I just bent the power cables back a tiny bit.



If you do not have proper desoldering tools however, I'd recommend you use a saw or carefully cut away the power connector. The pads on the PicoPSU comes off easely, so you risk ruining your nice new PSU if you try without the proper equipment.
I desoldered the first one (that I split into 4) but this one, I sawed off using a thin metal hobby saw. Just make sure to saw at an angle into the power connector and not into the PicoPSU.
After that, its very easy to remove the pins on the PicoPSU since you can do them one at a time.

 

Nice clean work. I like.

 

I joined the Pico PSU club today!

I have a 4-wire region free bios mod on the retail bios on this board along with a piggy packed bios chip. My plan was to flash the second bios chip so that I would load Dreamshell from the SD card, though I've recently learned that's not possible with a VA0 motherboard. Next step is to install a molex power connector and IDE port for an external hard drive. And of course a VGA mod.

 

Which pico psu specifically are you guys using here?

 

I got these. A bit overkill though I think.

http://www.ebay.com/itm/111377108201?_trksid=p2057872.m2749.l2649
http://www.ebay.com/itm/221317552930?_trksid=p2057872.m2749.l2649

 

Any one you can get will basically work, the DC draws under 30W at any time IIRC. The answer is in these pages.

 

So, has anyone tried running a DC fanless after replacing the PSU, installing a GDEMU or similar device, and possibly beefing up the heatsink? I know a passively cooled heatsink won't be cool to the touch, but I'm curious if it stays at an acceptable temperature so we could have a completely silent DC with no moving parts.

 

I still get heat coming out from the fan, even with a PicoPSU, so I doubt it. You'll need to replace the heatsinks at the very least.

 

Completely fanless ? I doubt it can be done safely. I use an xbox360 heatsink in mine and still at least 1 fan is needed.

 

With a picopsu and heatsinks it's clearly feasible but it might reduce the lifespan of the console a bit.

 

I assume you would be able to power the hard drive from the pico yes ?

 

Yep, no problem powering the HDD.

 

I already have the Pico PSU here but I need to buy a external brick. After reading the entire thread are we safe to assume 9v 4A is enough? Or better get a 12v 4A?

 

Be careful, most picoPSU take only 12v as they're input. The ones made for carputers can take a range in init voltage. Check your model datasheet to be sure.