Sega Saturn NTSC-J Blown Power Supply

Hey guys. First time on the forums here. I've come here before to read and look at some guides but It's only until today that I've signed up for the purpose of asking for help.

I live in Australia. I recently bought a Japanese Model 1 Sega Saturn from Japan with the intent on using it here with a 240 to 120 stepdown converter. It arrived in the mail and I booted it up and everything was working normally with the stepdown converter.

I'm sure you've heard this foolish mistake made by people many times before...But one day I decided to turn on my Saturn without checking where the power cable was going to and was shocked to hear a loud crack followed by my Saturn immediately shutting off and a foul burning smell emitting from the back of the console.

OOPS

I had accidentally used the standard two pronged power cable that I use for my PAL ps2 that was directly plugged into the 240v Mains. A total dope move.

Now, I'm not very good with actually identifying and fixing electronic parts. I can identify when things like capacitors are on their way out and I've done some basic soldering. But I tried to open up my Saturn and take a quick look at the PSU and determine that damage that I had done. All the capacitors look fine but towards one end of the board there was what looks like a glass tube fuse that had been shattered and the remaining glass had been discolored in a black smudge. Most likely due to the explosion on power. Here's a link to a gallery of the photos I took.

(I removed the glass tube)
http://imgur.com/a/UQfUD

For contrast, here's a photo of what the fuse should look like. (different model power supply though)
http://www.the-liberator.net/site-f.../Sega-Saturn/Sega-Saturn-020-Power-Supply.JPG

I probably need help in identifying and replacing this fuse. I've also seen people just putting in a one of those Pico power supplies like they do in the Dreamcast but I'm not really sure of the viability of this in a Saturn. Opinions are greatly appreciated.

TL;DR: How would I go about replacing the PSU in my Japanese Model 1 Saturn for use within Australia?
Replacing Fuse?
Putting in a Pico PSU?
Buying a new Jap Saturn altogether?

 

The fuse is 5x20mm, 1.25A, 250V, Fast blow.

There are lots of parts you could use - this is just a representative sample:

http://www.digikey.com/product-detail/en/bel-fuse-inc/5ST 1.25-R/507-1247-ND/1009019

I would also examine the surge suppressor for damage (this is the grey part marked CN5 next to the upper fuse clip) - if it appears undamaged, then just try replacing the fuse. The main filter cap (C3) looks OK (or at least it didn't vent) - but if you find the unit works but sometimes crashes, you might want to change that, too.

 

Alright. I went and bought a new fuse.

But upon further inspection the big capacitor (the one right next to the fuse clips and the surge supressor) appears to have some leakage on the bottom of it. I'm sure this isn't normal? Here's a photo for reference.
http://i.imgur.com/lq0EuvF.jpg

EDIT: I think the surge supressor has also blown. Looking at it from the otherside it has collapsed in on itself and looks buggered. How easy is that to replace?


BTW, Thanks for your help TriMesh.

 

If you mean the white stuff, that's normal - it's staking compound to hold the cap down to the board. Have a close look at the top of the cap, and see if there is any sign of bulging - if it's still completely flat, it's probably good.

The surge suppressor is easy to replace - it's just two pins soldered into the board. Normally when they blow, it's quite obvious - there are holes in the encapsulation and burn marks.

 

Yep that's exactly what happened.

Would buying one of these be the way to go?
http://www.ebay.com.au/itm/Metal-Ox...hash=item53da13a334:m:m3n2CqutICPL_7ZdfXEBl6Q

 

Probably too big - 14D is about 17.5mm, and I don't think that would fit. I think the original part is something more like this:

http://www.digikey.com/product-detail/en/panasonic-electronic-components/ERZ-V07D221/P7189-ND/137283

 

Should I go ahead with getting that exact varistor or a fairly similar one from my local electronics shop? I don't know what i'm really looking at so I just showed the guy with the fuse and he got me the right one.

 

I'm using a pico PSU in my Saturn and it works great. So if all else fails, it is an option.

 

Strange, I thought I had replied to this already...

It doesn't have to be that exact part - just something that's the right size to fit on the board. You should also make sure they understand this is a 100V/120V unit, since I've seen quite a few previously repaired Saturns that have had varistors rated for 220V operation installed in them - and although they look perfectly decorative on the PCB and the unit will work OK, they don't actually do anything because by the time the line voltage got high enough for the varistor to conduct the rest of the PSU would likely have already been destroyed.

 

x

 

Hey there. It's been a while, time for an update.

So I went ahead and replaced the fuse and the varistor. The saturn now lives again! Many thanks to you guys for the help.

Although, I've tried playing genuine cd's in the saturn in addition to burned cd's using the Pseudo Saturn method. And on some games, usually ones with polygons, I'm getting vertical bars and other graphical junk on screen. Bulk Slash is pretty glitchy. I tried playing policenauts which is strictly a 2d game and didn't have any problems, but it's mostly games with 3d effects or polygons that seem to shit the bed. Here's some photos

Bulk slash title screen. Not correct at all
http://i.imgur.com/rIhQSbS.jpg

Bulk Slash gameplay. Notice the horizontal "jailbars"
http://i.imgur.com/C5ZeK7q.jpg

Here's Deadalus. running from a genuine game cd. Notice the vertical bars this time
http://i.imgur.com/1I8I4J2.jpg
and another one which is completely messed up
http://i.imgur.com/pdWTUMv.jpg

This seems to be a hardware issue. Could I have possibly messed something else up when I initially blew the PSU? I'd like to know what you guys think.

 

That could be a couple issues. The best thing to do is run it without the giant metal shield (but use the insulator piece for the power pcb and tape under the AC solder points!) and gently press on the middle or upper middle left side of the board. This will let you know if the problem is related to poor solder connections between the ASICs (VDPs). I fixed a Saturn with this exact issue recently by reflowing some ASiCs.

The other thing it could be (less likely) is that your 3.3v line is bad or voltage is too low. 3.3v is used in the Saturn ONLY for the RAM. If your "new" power supply / repaired PSU has a weak 3.3v line it could be possible that would get artifacting on some games.

lastly, it could be your VRAM going bad. But lets hope not!

-Segasonicfan