Dreamcast GDEMU or SD Adapter

[SpaceBooger]

Which "cheaper SD adapter" are you referring to?

The other problem has to do with the Dreamcast's power supply. The GDEMU really only works with the VA1 revision. But even then, it leaves the 12v power rail unused. Without a load on the 12v rail, the voltage spikes and the power supply starts to overheat. So if you're installing the GDEMU, you really want to remove the 12v regulator (a good tip is to turn it upside down and screw it back into the heatsink, that way it's always there if you want to reinstall it). Also, if you have a VA0 revision Dreamcast, you may or may not have a potential problem. People seem to argue back and forth about the VA0's.

Ok Ziggy I bit the bullet and got a gdemu. I am finding tons of conflicting info on the 12v mod. I trust you a lot so can you point me in the right direction to complete this.
Thanks.

[Ziggy]

So from what I gather, for GDEMU installs people either remove the 12v regulator or put a load on it so it doesn't overheat. A 12v load would be a fan or a resistor. But since nothing requires 12v outside of the optical drive, I think the best option is to remove the it. I mean, why needlessly waste electric?

Is that what you meant by conflicting info? Remove the regulator versus putting a load on it?

[SpaceBooger]

Some say remove only the 3 pins and others say do that along with the little resistor next to those pins as well

[Ziggy]

Ah, OK. To be honest I never heard of removing that resistor until now.

https://console5.com/techwiki/images/6/ ... -13570.png

Above is a schematic of the Dreamcast PSU, in the top-right corner is Q2 which is the 12v power regulator. I guess the resistor in question is R16. If you remove R16 then it takes D4 out of the circuit as well (or you could remove D4 to get the same effect, I'm assuming R16 is more convenient).

It's easy enough to remove chip resistors even if you don't have a hot air station. You just position your iron tip so that you're heating up both sides of the resistor at once, adding some solder to bridge both sides, then it'll just lift right off. If you're quick enough to get the resistor off the tip of the iron before it's destroyed (you can flick it off inot a cup or something, or grab it off with tweezers if your fast enough) you can "tombstone" it back onto one of the pads. Check the resistor first with a multimeter to make sure it wasn't burnt up first, of course. Just like turning the regulator upside down and bolting it back to the heatsink, it'll be right there ready to go if you ever need to restore 12v. On the other hand, a resistor is as generic as a part can get, so I wouldn't be heartbroken if I burnt it up while removing it.

[SpaceBooger]

Here is the image that is used in almost every guide about removing the 12v rail. Notice the three pins to remove the piece but also the resistor (R16) being marked as well. This guide specifically states that you need to remove the little thing along with the regulator: https://imgur.com/gallery/5AtCG

This video (around the10 min mark) shows just removing the 3 pins for the resistor and turning it upside down as you suggested. I trust the video but like I said I wanted your opinion.

The last solution other than a DreamPSU was to add some resistors the PSU itself:

Even better than that is three 1Kohm 1/4W resistors in parallel (creating a resistance of 333.33ohm), as the load is shared between the three.

Link: https://retrogamesultra.com/2019/02/17/ ... omment-953

So Ziggy, what do you reccomend?
The 3 resistors would be easiest, but the removal of the rail the cheapest... but do I take off that small 102 (R16) resistor thing as well?

[Ziggy]

I feel like adding resistor(s) is an option for people that don't know how to solder. That's not to say it isn't a viable option. It's adding a load back to the 12v rail, which will keep it from overheating. But now you're wasting electricity on a 12v rail that you don't need to use for anything, except to keep a load on it so it doesn't go out of control and overheat. Also, jamming resistors into that socket is not at all a sound installation. They have the potential to dislodge, and without you knowing about it, and then that could cause issues form overheating. Also, I'm not sure why you would use three 1/4w resistors instead of just one that can handle a larger current. Maybe there's some reason I'm not understanding (again, I'm not EE) but my guess would be that 1/4w resistors is what someone had on hand one day, so that's what they used, and now that's what people parrot. If you're gonna add a load back to the 12v rail using a resistor, use a single resistor of an appropriate value (or three, if you have to) and solder it in. But again, you're still wasting electric on a 12v rail that isn't needed. And even with the load, you're adding heat when the 12v rail isn't needed.

So personally, if it were my console, I would remove the 12v regulator and resistor.