Saturn Power Supply Failing - Repair Ideas?

Hi everyone!
Looking for a little help with my Saturn collection :tranquillity:
I've got two Model 1 Saturns - One with a dead PSU and another with a failing PSU.
They are both five pin PAL power supplies.
Thankfully my model 2 Saturns have compatible power supplies and was able to test - they work just fine.
A lack of decent power supplies though is a bit of a problem.

Anyway I thought I had a good decent PSU in this particular model 1 unit, however after an hour of playing, powering off / restarting causes some crazy horizontal lines to appear.
You can see the lines showing up here http://www.youtube.com/watch?v=ru07hk_idHY

So I recorded it (see above) and noticed a hissing noise that the camera was picking up from the Saturn that I did not pick up.
After a few tests back and forth I found that the hissing only happens after it has been running for around an hour and will not occur unless the Saturn is restarted.

Here's two videos of the hissing noise going happening
http://www.youtube.com/watch?v=h4uCTT9GqpE
http://www.youtube.com/watch?v=0lqGrb4LiUc

Sadly I have no degree in electronics but would love some ideas on what could be causing this.
The camera I used had stereo sound so I ran it up and down the power supply to try and capture the source of the noise (or at least the area).
Here's a photo of the two power supplies for comparison - The first with "K461" on the transformer is the bad unit, the other is pulled from a working model 2 Saturn.

View attachment 3075

View attachment 3074

Anyone got any ideas on how to repair or a place from which to source PAL power supplies for these beasts?

 

There are a number of parts on a power supply that can cause a high pitched noise to be created. I would suspect that something is failing and the easiest (and cheapest) components to replace on the board would be the capacitors which can and do fail. None of those on your board look like they're failing to me (one typical symptom is leaking and/or bulging) but that doesn't mean anything on its own.

Not entirely sure but I want to say the voltage regulators, transformer and the inductor can all make high pitched noises. They're not too difficult to replace but they may be more difficult to source replacements for being you're in Australia and I have no idea what the state of Australian component supply is like for end users.

Only seeing 9 electrolytic capacitors; personally I'd start there. Hopefully someone else can chime in who has more experience with power supplies than I do (I'm looking at you Calpis).

 

Yeah I was having a dig around to see what components I can source. Things like the transformer I wouldn't have any idea what I would actually be looking for.

Caps are certainly the easiest ones to go through and replace, so I should go through and just pick some up and replace them anyway. If they solve the problem that would be pretty spectacular.

The sound definitely appears to be coming from the centre of the board though. So I'd be inclined to try the transformer or transistors after the capacitors.

Thanks for the input! Is Calpis a whiz at this type of thing?

 

ALL Pal saturn power suplies are 5 pin. But they have different pinouts. So I'd watch out with that. Actually, scratch that, the ones with the different pinout also have different form factors, so you physically can't fit them inside the machine.

I have that exact same problem on one of my saturns. It's caused by overheating. I've installed a small cooling fan in that machine (small like the one in the Dreamcast), and after that it could do daily 10 hour marathons without a single issue.

 

Can you please post high resolution picture of the solder side of the power supply circuit board ?

Also DruidII, can you post a picture of your power supply too ? High resolution so the solders can be seen properly.

 

Ah right, I was not aware! So two different form factors on the power supply - will keep an eye out for that. I believe mine are all the longer versions. Were the shorter ones for later revision Saturns?

I'll do it first thing tomorrow at work on our scanner. I've got scans and photos of everything, except the underside of the board. Thanks for helping too!

 

http://imageshack.us/photo/my-images/407/dscf0376u.jpg/

http://imageshack.us/photo/my-images/171/dscf1301oo.jpg/

When did imageshack remove thumbnails by the way?

Yes, in the model 2 single board machines. VA6 and later motherboards. They use two GND and two 5v rails instead of GND GND 3.3v, 5v, 9v. PAL machines have a fifth pin, a 9v/12v one, needed for SCART output (and used by nowhere else on the entire board).

 

So if I don't use SCART I don't need the 9V/12V connector connected to anything? I am trying to think of another way to wire my other powerless Saturn Model 1 to an external power brick or two in case an decent working internal PSU can't be sourced (or repaired for that matter). So I'd just need 3.3v and 5v?

 

Late model 2 machines only use the two ground and 5v pins for the mainboard, and only the scart uses the 9v pin.
Model 1 and early model 2 machines use all three pins. The 5v is essential, but I'm not sure where exactly the 3.3v and 9v pins are used (outside the Scart pin). It also may vary from board to board (there are 3 entirely different PAL boards).

You should just try finding another saturn power supply, any model 1 power board should work as long as they are bottom mounted.

 

That does sound like the path of least resistance, which happens to be my favourite path, but where can I find them to suit 220-240v? The only ones I have come across so far are the 100-120v variety. That said, I might as well try using an external PSU anyway - if anything just to cure my curiosity. Definitely thanks for the tip on the 9v / 12v SCART thing though. That definitely gives me more motivation to push on!

 

If that is the case you may be better off getting a good voltage converter and not have to worry about it. The only places in the world that I'm aware of that shipped with 220-240v power supplies were the PAL territories (and SECAM I suppose).

Making a power supply universal by swapping out the transformer and fuse wouldn't be a half bad idea but if I were to do that I'd want to swap out the lousy connector whose screw holes bust wide open at the drop of a hat.

 

Asia models got 220v power supplies as well. But that machine usually costs more than a vanilla PAL unit. I'd just buy a machine cheap from one of the european ebays.

 

As promised and without further ado, here's the underside: http://img24.imageshack.us/img24/2218/basegr.jpg
And here is the top as a bonus: http://img35.imageshack.us/img35/6167/topung.jpg

 

Would be cool if i can find T1 the yellow part replacement thats whats wrong with mine i did replace all the caps but still buzzed and switch off after 5 mins.

 

The soldering on the inductor looks questionable to me. And what is going on towards the rear square in the middle? Looks like someone tried to reflow the solder but stopped before the iron melted everything.

The transformer? Probably a bog standard model. Thing is the output voltages may vary depending on PSU design so I can't point out a proper replacement without taking one of mine apart and probing it.

 

Ok but if you could help me find a replacement i would be greatfull thanks mate.

 

I've give them a reflow tomorrow then at the office and see if there's any change.
Reckon I should reflow as many of the solder joints on the board while I'm at it?
I've gone through and mapped out the capacitors and other smaller components that can be replaced easily.
I've still got another Saturn model 1 PSU (Same design as this one) that gives no power at all, yet has no apparent damage.
Thanks again for helping with this one, it really is appreciated! :loyal:

 

Alright! I went ahead and gave the bad looking solder joints a bit of a warm up and reflow.
Unfortunately I am still getting the wavy horizontal lines. Next step is capacitor replacement town.
Will keep everyone posted of the progress, hopefully this will help someone else down the road if I end up getting it working! :smile-new:

 

i have a power suppy with the same fault mate and i replaced all the capacitors still did the same good luck.

 

All I can do is dream! Besides I have two :tranquillity: One that is broken and one that is breaking :livid: