230v Dreamcast power supply

The DreamCast runs off 3 voltages, 5v and 3.3v which you could use two step-down regulators, and 12v line which runs fine 7.2v-12v. If you are handy with a soldering iron, and have a multimeter, you could provide a male/female port to the console to plug in a transformer (7.2v-12v at 3 amps or more); connect to the power in pins and rig up the two step-down regulators (after you've set their voltages correctly).

If you are not handy with a little modding, then yes, you need an original PSU supply. When you get one, hold it carefully, as if there is any charge in it and you touch the capacitors, you will get an electric shock which will be painful. I've done that before, gives a bit of a jolt!

 

There is a thread on here about using a Pico (clone) ITX PSU. IIRC it's in the dreamcast sub-forum

 

AS per standard PSU construction, the large mains (usually the filter caps) caps will have discharge resistors across them, any residual current is often dissipated in a short while..

 

Nope, otherwise i'd not have had a shock a couple of years ago.

Pico PSU costs a lot more than a couple of £1 step-down regulators and using an old transformer not being used (i'm sure everyone has some lying around).

http://bacman.co.uk/regulators-2/

 

Gros malin: lol:
moi je vois ma sign , tu la vois pas ? ais je été censuré ? ou quelque chose que j'ai pas coché ?
http://darius-saturn.fr/forum/index.php
http://darius-saturn.fr/convertir-alim-dc-110-en-230v/

 

Wise guy: lol:
I see my ign you not see? ais I been censored? or something that I have not checked?

 

Did the guy that did that mod check to make sure the transformer wasn't saturating, or did they just assume it was OK because it didn't immediately blow up?

 

several members of my forum made this mod and nobody complained

 

I didn't say every PSU is designed this way and I didn't say how long the discharge takes!

Using regulators may be slightly cheaper but very messy and unless you are building a circuit using switching regulators, you are going to have to dissipate a considerable amount of heat.

Here is the thread where Rocky5 successfully replaced the PSU and fan

http://assemblergames.com/l/threads/replacing-the-dc-psu.53856/

You can still run it off any (suitable) old crappy wall wart you have laying around too..



Clean up the old IEC8 hole with a square piece of plastic with the barrel jack mounted in the center. Original power button works, more current for stuff like ODDE's, LED's and other stuff.

 

The £1 each regulators I referred to are switching regulators, so not only very efficient (around 92%) but also work cold so no issues at all with heat, and the boards are very tiny too - the size of a normal postage stamp roughly each.

 

Just mentioning in addition to what TriMesh said, Tec Toy had modified those Japanese PSUs for "V0" Dreamcast units sold here in Brazil to be "full range" (100-240v) they had the main switching FET transistor, a couple of resistors under the PSU board *and* the chopper transformer replaced with modified ones.

Additionally they replaced the BIOS maskrom with the newer one which supports regions other than Japan and flashed USA disk/PAL-M video system settings on the flashrom.

 

I have seen similar full range power supply boards having been sold on GameForFoun. The operating voltage is 80 to 220V...

http://www.gameforfun.com/en/product.asp?product_id=144

Ted.

 

You can certainly make a PSU in that form factor with wide-range input. I'm just a bit nervous about trying to run the existing transformer on a much higher line voltage without doing some tests to ensure that it's not operating outside limits.

On the PSU I have here, the line voltage range is specified as being between 85V and 132V (presumably 100V nominal - 15% and 120V nominal +10%) - if we take the stated high line condition as 132VAC then the peak voltage out of the filter cap would by 132V * sqrt(2) = about 187V. This is within the voltage rating of the 200V filter cap installed on the board, and presumably the board is happy to operate under these conditions.

In the EU, the nominal line voltage is 230VAC, although the actual voltage varies quite a bit - most of Europe used to be nominally 220V and the UK was nominally 240V - this was "harmonized" by the simple expedient of increasing the line voltage tolerances to a point where they were wide enough that both 220V and 240V were inside the spec. The actual range is specified as being 216V-253V, with mainland Europe tending towards the lower end of this range and the UK tending towards the higher end.

If we take the 253V stated highest line condition, then the peak voltage across the filter will be 358VDC - so clearly you need to replace the cap with one rated at at least 400V, and this (along with replacing the bleeder and startup resistors) is what the linked mod does.

But that's all it does - there are other effects from the higher DC bus voltage, and no attempt appears to have been made to verify if the other parts of the circuit are operating inside their spec. The system should stay in regulation if it's well designed - the PWM controller will simply reduce the pulse width fed into the switch to give narrower (but higher current) pulses. The potential issues with this are that (1) if the transformer saturates then the current through the switch will start to rise exponentially at the end of the pulse, which will heat up the transformer, switching device and the rest of the circuit, along with causing a drastic decrease in efficiency (2) even if the transformer doesn't saturate, the higher DC bus voltage will result in an approximate doubling of both dI/dt and the average current through the switching device during the on time and (3) when the switch turns off and the field collapses the back EMF will also be approximately double, which might exceed the ratings of the switch device or possibly the other parts in the snubber circuits.

Sure, it might be fine - but since I happen to know a little bit about the design of switch-mode PSUs, I just think it's worth pointing out that just because the unit runs for a few days (or even a few months) that doesn't prove that it's all operating inside spec.