Dreamcast VA0 - is a PicoPSU recommended?

[bobrocks95]

I have a VA0 Dreamcast and my main concern is the heat on the PSU heatsinks. The L-shaped one closer to the front passes around 71C or more after an hour of the console being on. The heatsink directly behind the fan in the VA0 keeps the CPU and GPU cool, but blocks virtually all airflow to the PSU. The plastic lid even gets fairly hot on the underside and under where discs sit.

I saw Voultar covered the DreamPSU a bit and results were poor with ripple and potential video interference. Have PicoPSU's been tested in the same way at any point? It looks like there are lots of different ones you could potentially get.

Maybe 71C isn't cause for concern? I've never run PC components that hot, but I can't say I've paid attention to PSU temps either. For a 22-27 Watt system that sounds crazy to me and I question the longevity of a part running that hot at all times. My 350W RTX 3080 runs in the mid 60's at full load- that's of course with active, direct cooling, but it's also 13x as much heat to dissipate, if not more when you consider the PSU isn't the only thing converting power into heat on the Dreamcast.

So, any cause for concern, or just stick with stock?

[TooBeaucoup]

The advice I see from Voultar as well as most of the other major modders is to recap the original PSU. It's a high quality PSU and replacing the caps makes it the best option out there. With that said, the Pico is fine, only if you get a legit one and not a cheaply made clone. Also, you have to worry about the power brick you attach to it. If you end up with a cheap one, you could damage your Dreamcast. The biggest problem with the Pico is many people have made versions of it, so not only do you have to make sure you don't buy a crappy one that was made poorly, but you have to worry about the power brick, so you've got two things to worry about. With the original PSU, you know it's good quality and designed properly. You just need to make sure the caps are good. I've recapped dozens of them and almost all of them had at least a couple of leaking caps on the PSU.

Here's an article from Bob at RetroRGB talking about the DreamPSU, but this holds pretty true for the Pico as well.

https://www.retrorgb.com/dreamcast-repl ... lysed.html

[bobrocks95]

I'd prefer to stick with stock for sure, I'm just concerned about the amount of heat it's creating. Would a cap replacement reduce temperatures? Mine isn't failing or anything, just pumping out a lot of heat.

[VEGETA]

I'd prefer to stick with stock for sure, I'm just concerned about the amount of heat it's creating. Would a cap replacement reduce temperatures? Mine isn't failing or anything, just pumping out a lot of heat.

Recapping has nothing to do with reducing heat but rather making the PSU work as intended. Failed caps if they are in parallel won't stop the PSU from working but will degrade its performance in terms of ripple suppression.

I would recommend you to try and fix your stock PSU, but if it has problems then you shouldn't use it at all.

I know DreamPSU has lots of ripple and noise but won't hurt your Dreamcast. Other ones like ReDream is better, ReDream promises about 30mV ripple and noise which is not impressive either.

This was my motivation for making my own PSU and I used a brand new regulator IC which is phenomenal as it promises < 1mV total ripple and noise! I had a prototype 5 boards and they work fine! my only complain is that the 5v rail is delivering 5.13v instead. However, I ran my DC with it for no reason at all. I even supplied it with very very bad 12v brick and it reduced the noise and garbage of it to a high degree, unlike ReDream which delivered much more noise and garbage.

I made a few enhancement to the design and will make a very small batch soon, I hope.

Therefore, I would recommend you now to get your stock PSU fixed and verified. Not just re-capping! or just in case buy a ReDream or Behar brothers PSU to use while your stock PSU get fixed.

On the other side, stock PSU are not always the best since they might not be made by Sega or Sony but rather in China using very cheap components to save cost. Most of these are even single layer board (not DC one though)... However, they are still safe to use.

Also, high temperature will kill your device as time passes. Especially that it is already +20 years old. I assume even a little more ripple voltage (which won't affect visuals by any perceptible amount) is a lot better than high temperature inside a retro system.

[クリスチャン]

I have a VA0 as well. The heat is coming from the MOSFETs which are usually rated to around 125-150C. Max I've measured directly on the FETs with a thermal couple was in the 80s I think. I applied some thermal paste between the FETs and heatsink as there was none on mine; this seemed to help a little. The caps don't get super hot from what I remember and are of decent make. I've yet to see bad caps on a Dreamcast PSU, but one of these days they'll probably go bad.

[bobrocks95]

That makes me feel better, at least the components themselves are designed to handle that much heat. I wonder if it's possible to replace just them with more efficient ones- they're the 3 standing transistor-looking components bolted onto the heatsink right? I guess it may not be trivial to find one with matching specs.

[クリスチャン]

That makes me feel better, at least the components themselves are designed to handle that much heat. I wonder if it's possible to replace just them with more efficient ones- they're the 3 standing transistor-looking components bolted onto the heatsink right? I guess it may not be trivial to find one with matching specs.

It's extremely trivial I would assume. I haven't looked into the specs of these specific FETs, but I would be absolutely shocked if digikey or mouser didn't have similar or same rated MOSFETs. I honestly wouldn't worry too much about it. The only thing I did with my PSU was add some thermal paste and cut the vertical part of the plastic insulator since I have a MODE.

[Konsolkongen]

Don't worry about it. It was designed to handle that amount of heat. While your GPU in your PC may not exceed 60 degrees I would be surprised if there wasn't a lot of other components in there that runs much hotter.

[VEGETA]

That makes me feel better, at least the components themselves are designed to handle that much heat. I wonder if it's possible to replace just them with more efficient ones- they're the 3 standing transistor-looking components bolted onto the heatsink right? I guess it may not be trivial to find one with matching specs.

It's extremely trivial I would assume. I haven't looked into the specs of these specific FETs, but I would be absolutely shocked if digikey or mouser didn't have similar or same rated MOSFETs. I honestly wouldn't worry too much about it. The only thing I did with my PSU was add some thermal paste and cut the vertical part of the plastic insulator since I have a MODE.

Well, not so easily. When considering MOSFETs especially in linear region of their operation... you MUST study the curve very precisely to make sure it offers the same or better reaction on the same load and gate voltage. It is really not trivial or easy task at all. I wouldn't recommend replacing the mosfets just like that, they work properly , therefore just do some thermal paste and so on.

Don't worry about it. It was designed to handle that amount of heat. While your GPU in your PC may not exceed 60 degrees I would be surprised if there wasn't a lot of other components in there that runs much hotter.

well, yes. However, that much heat is not healthy at all and if you can reduce it by good amount then go for it. As I told you before, stock power supplies is not always good quality since they are most likely not manufactured by the same company such as Sega or Sony but rather off-loaded to China in order to reduce cost. China is good about cheap electromagnetic components such as SMPS transformers. I looked into the Dreamcast PSU and found an ok transformer but many other components are generic and some of them have no brand at all. Caps look nice though, and you just replace them with any cheap capacitors which will last at least 5-10 years.

I have designed a new power supply for Dreamcast which is low heat low noise\ripple. However, it takes input from an external brick. It will retail for about 45$ which seems nice since all good ones are the same. However, I can design a power supply that takes AC input directly exactly as the stock one but it will be much better by using professionally made power modules. However, its retail price will go to at least 80$ which I don't think people will pay right?

BTW, you can get PSU replacement which is identical to DC stock psu from Aliexpress for about 10-20$ or so... which signifies how cheap and generic it is.

[Konsolkongen]

A quick google image search shows that the Dreamcast PSU is made in Indonesia or Japan. Regardless of where it's made I don't really see that as much of an issue as long as they are manufactured to the specifications provided by Sega.

[クリスチャン]

That makes me feel better, at least the components themselves are designed to handle that much heat. I wonder if it's possible to replace just them with more efficient ones- they're the 3 standing transistor-looking components bolted onto the heatsink right? I guess it may not be trivial to find one with matching specs.

It's extremely trivial I would assume. I haven't looked into the specs of these specific FETs, but I would be absolutely shocked if digikey or mouser didn't have similar or same rated MOSFETs. I honestly wouldn't worry too much about it. The only thing I did with my PSU was add some thermal paste and cut the vertical part of the plastic insulator since I have a MODE.

Well, not so easily. When considering MOSFETs especially in linear region of their operation... you MUST study the curve very precisely to make sure it offers the same or better reaction on the same load and gate voltage. It is really not trivial or easy task at all. I wouldn't recommend replacing the mosfets just like that, they work properly , therefore just do some thermal paste and so on.

It's not hard, just look up the datasheet for the parts. Modern parts will outperform these old parts easily.

[Bassa-Bassa]

Wondering if I could get some good advise to replace one of my DC's PSU now I'm installing a GD Emu clone. It's a Japanese VA1, though I have a VA0 as well with a working PSU, unlike the former.

I'm asking because it doesn't seem to be entirely clear what's the best of all the homebrew units out there in 2023. The Beharbros one isn't available and didn't get many reviews, and I don't think I myself could find a reliable Pico PSU together with a reliable adapter. Recapping the original ones is not an option for me either, I'm afraid.

So what do you think of Rexus' Redream? Should I be particularly careful with the adapter I buy for it as well?

https://rexusnexus.com/product/sega-dre ... dream-psu/

Would you just use the working VA0's PSU with the VA1?

TY.


Ed.- While we're at it, is a replacement of Saturn's PSU also recommended at this point, with or without an ODE?