SOLVED Sega Saturn Model 2 PAL Broken PSU

Hey there,
I decided to sign up here and see if anyone could answer a doubt I have about my Saturn.

Here's a little backstory:
A few weeks ago I was playing some Worldwide Soccer 97'. I turned it off, changed the disc, and suddenly it doesn't power on. No cracking, no sounds, no anything.

Eventually, with help from some people, we narrowed the issue down to the electronic transformer. You know, that black and yellow piece that turns AC into DC. The console itself is fine though!
Now we're trying to repair it. But before we buy any replacements...

Here's where the question arises: Everyone on the Internet states that their power supply's pins go like this:
12/9V (depends on region), 5V, 3.3V, and two Ground pins.

But if I look at the underside of my own board, I see what appears to be two 5V pins soldered together. The PSU also has no indication of any 3.3v point. Picture attached.
I did find other pictures of this exact PSU online with those two pins together, but there's no statement on whether that's two 5V rails or not. I also can't measure the voltages myself because the transformer is broken, so no current actually goes to the pins and therefore the console.

Can there be two 5V pins and no 3.3v one?

Thanks in advance.

 

Yes, that 5V only setup is common for the later model consoles. This is one of the reasons you need to be careful when swapping Saturn power supplies since putting the new PSU into one of the older consoles puts 5V onto the 3.3V rail for the SDRAM.

 

Oooooh I see.

Original PSU replacements for this later model are hard to come by here. Last one we saw got sold out just as we were about to buy it.
I'd get a PicoPSU but it's not exactly cheap. I'll do if I have no choice though.
So, if I ever come across a replacement, I'd hate to mess up

All in all, if I were to go full DIY and like use a computer PSU or an external adapter, I wouldn't need 3.3v.

Thanks!

 

Another thing that might be worth noting is that you might not need the 9V line either - it doesn't run anything inside the console, just comes out on pin 1 of the video socket so that it can be connected to pin 8 of a SCART cable to force 4:3 aspect ratio. This is also why the NTSC versions of those later consoles only had a 4-pin plug on the PSU and didn't have that 9V output at all.

 

Oh wow, so the entire console runs on 5V... Very interesting.
So, in case I managed to find an external 5V adapter (assuming the current is right, PSU says 3A) that would be enough.
Does that mean I wouldn't be able to use a SCART cable though? Or would it work just fine, only that it wouldn't be forced to 4:3? Just so I know if I have to get another cable with like composite output.

 

It depends on your TV - that signal both enables the SCART input (if > 2V) and forces 4:3 aspect ratio (if >= 9V) - so if you can manually select both SCART mode and 4:3 you don't need the signal at all. If you can't manually select SCART, but you can manually select aspect ratio then wiring it ot the 5V line from the console will work.

Or you could put a ICL7660 running in voltage doubler mode from the 5V rail into the SCART cable to generate ~10V for pin SCART pin 8. This is what I did with my cables I was using with my NTSC Saturns, since they don't have that 9V output in the first place.

 

Interesting.

Turns out, we actually gave it a go yesterday. We took 5V from a computer PSU, and soldered it to the Saturn's power pins. It actually works! Even displays video normally. Only thing is, when using a video adapter (i.e. Scart to RCA) it won't display anything. It'll only give a signal if it's connected directly to the TV. Is that supposed to be normal? I say it because I often find myself using adapters a lot for various reasons, like connecting the console from a distance, using very long RCA cables. So losing the capability to adapt the signal is impractical for me.

If it is normal, then I personally don't plan on making any further changes, so once I look for a fancier solution to power the console (small power brick, and having an actual connector instead of bridging two wires every time lol) I think I'll just get a cable like this and be done with it: https://www.amazon.es/Retro-Bit-Sega-Saturn-S-Video-Cable/dp/B00FEO58G8

 

Sounds like an issue with your adapter or wiring.

What scart cable are you using? RGB or Composite? If RGB and you want to goto RCA, you need to be using an RGB cable that uses composite video for sync. If its using Csync, you wont get a picture.

 

Kind of a hijack, but has anyone tried this? http://s.aliexpress.com/Qz2qIzu2

 

I used a genuine Samsung charger (not a quick charger, this one is older), it works nice so far.

It had issues with modchip not running some discs with old PSU, the same issue reported in a video, the backup disc works fine with console opened but fails to boot after closing it.

 

Samsung charger eeh. So how much juice is one of those capable of? 2amps? Is ther info anyware on what kind of ampage each rail riquires on each model?
I know there is talk about early PAL models requiring 9v for the cd motor and the rgb switching.
But latet models only for the switching?

Bottom line. It would be easier to hack something nice together for a low price if we had the specs, instead of relying on those overkill pico PSUs.

I hate Voltek!

 

I had a drive that only worked with case off or lid open but switch forced shut.

Was a weak laser.

I have a bench PSU and wired it up to a saturn. I could probably log current usage in various tasks. But its no more than a couple of amps iirc on the few I was repairing.

 

Honestly, I have no idea. It's the one that came with the console when we bought it. The one thing I know, is that before the original supply died, the adapters did work. I could adapt the signal to RCA and S-Video no problem with the exact same adapter. Now, it does like noise/interference on the screen (it's a CRT) but no signal from the console. You clearly notice it's doing something, but not what it's supposed to do.
On a side note, my console is PAL, and from what I've read, PAL consoles don't have built in C-sync support.

My laser is fine though. We got a modchip last summer, and along the way we calibrated the laser with the orange screw in the back and thorough cleaning. Reads all games.

As an update on this post, a couple days ago I bought a new PSU from the electronics store. When I get around to wiring it up, I'll do another test and see if the video issue persists. Like I said on previous posts, it's nothing major and I can just have it connected directly to the TV, or just use another type of cable.

 

One thing i always found on PAL model 2s is that the caps r crap. The electrolyte seems to be so dry that if you touch them to hard with a little heat they explode! (The orange ones) i have had all kinds of troubble before changing them. Manley read errors.

 

That's actually never happened to me before. I've never replaced one on my original power supply, because they're completely fine to this day. Though I wouldn't be surprised if one were to break now honestly; this PSU served its purpose for 21 years until the transformer died. Way more than I expect for modern electronics.

 

My experience with Saturn caps has been pretty good too. I suspect it's because Sega preferred to use wave soldering and hence through-hole caps. As a result, the peak body temperature of the caps is way lower than it would be if they had used SMT caps and reflow soldering.

If you want an absurdly long-lived product, I've got an HP5245M frequency counter (with nixie tubes!) - according to the ink stamps on the chassis, it was built in 1972 and it still has the original caps in the power supply with '71 date codes on them. When I took them out and tested them, they were down to about 60% of their original value - but everything in that design was so over-specified that it didn't matter and it all still works perfectly except that the reference oscillator is off frequency (even if you trim it as far as it will go) - but I guess 45 years of drift will do that...

 

Damn, now that's what I call old.
The oldest thing I own is probably an NES clone. I've never opened it up though, so I can't say for certain if it has a date code and therefore and exact date, but it sure was made in the 80's. Works really good. The zapper did stop working though.

 

Also, when I thought about it a little more, I noticed the 50/60hz switch I installed on my Saturn a while back was set to 60hz. I've only used the adapter I have in 50hz mode. I was using 60 the whole time, and that could explain why connecting it directly to the TV gave signal but the adapter did not. The TV supports various refresh rates, but I'm not so sure about the adapter. I'll turn it on again, this time on 50hz, and check if the problem was me all along lol.

 

Quick update:
I hooked up the new PSU to the Saturn, but I did a fancy custom mod which I'll explain here:
I didn't connect the console straight to the new supply. What I did is take the original board, take all the components out, and use it as a mere passthrough. That way I can still plug in a two prong cable with 5V and GND, and use a couple cables to extend the signal to the pins on the console. (Of course, since I now feed the cable direct current, it can only be plugged one way, so I modified the shape of the cable and connector a bit so it's impossible to connect it the other way around)

The console now boots, but I have one problem. The console freezes at startup, regardless of whether or not there is a disc on. It seems to happen spontaneously; sometimes it goes further into the booting animation, or even goes to the menu, but as soon as you insert a disc, it either freezes or downright stops displaying.
A few minutes of troubleshooting with the multimeter later and I noticed the 5 volts get degraded the longer the cables are. If I feed it 5V, there will actually be like 4.8 or 4.9 that actually reach the console. I'll be trying with thicker, shorter cables later today, but do you have any other suggestions as to why this might be happening?

 

I know people are fast to say its the caps... but it the caps. And also there might be some ripple on your 5v but it shouldnt degrade like that sooo its the caps. I have had 5 model2 pal saturns with none working lasers that workes just fine after a cap change. And some times psu rebuild and cap change.