Faulty PAL Saturn PSU issue

[themanfromsaturn]

I have a model 1 UK Saturn fitted with a Type B (GND, GND, 3.3V, 5V, 9V) power supply.

After the Saturn has been running, say for an hour, then power cycled, it no longer boots. The system goes straight to the CD player and reports that the drive is empty. At the same time there are wavy lines on the screen and a whining sound coming through the speakers and unit itself.

Initially I thought this was the TOP202YAI issue, so I replaced this with a new one, but the problem persists. I swapped out the PSU with another I had spare and it works perfectly after a long run and power cycling, so it is definitely the PSU, but what component could be the culprit?

Having eyeballed the capacitors they all look OK, so I am a bit stumped.

Does anyone have any ideas as to what the faulty component(s) could be?

[zyrobs]

Have you replaced the TOP202YAI with a modern replacement (TOP224Y from the top of my head), or with just another TOP202YAI, which may be equally broken?

The capacitors may look OK on the outside, but dried up on the inside and barely holding to spec. They are 24 years old.

[themanfromsaturn]

I ordered and replaced it with a brand new TOP202YAI, not the modern version.

I could try swapping the one from the working power supply just to double check.

I will look at recapping. Do you recommend to replace all capacitors or just the electrolytic ones?

Everything works fine from a cold start or after the system has been allowed to cool down. Does that help give any further clues?

[zyrobs]

Only the electrolytic caps need replacement.
The TOP chip is probably overheating. The TOP202YAI has been EOL'd for over a decade, so you probably replaced a dodgy old component with a dodgy old component. It's why the newer one is recommended.

Try installing an extra cap on the PSU, as marked with green on this image:



I do both this and replacing the TOP202YAI with a TOP224YN when I'm fixing power supplies.

[themanfromsaturn]

Thanks for the image, that's really useful, but I think I've now wrecked the power supply anyway while I was tinkering with it. I was swapping components and now it will not power up at all  .

I'm going to attempt to build my own replacement power supply using off-the-shelf power boards. I've had some success with that approach on a Japanese system, but it was a bit easier as it was only 5V and GND needed.

Anyway, that's a separate project and I'll probably create a separate thread for that if anyone is interested.

[marcof]

Hi,

I have a Saturn model 837-11892-01 PAL VA1 equipped with a FUJITSU KS350-1401-H025/01 PSU.

I was having some video issues (trebbling image that faded away after 15min to 20min with the console on) and recapped the PSU.

After recapping, the PSU started to make some strange and loud noise and the initial video problem was "magnified" the picture was woubling always even after more than 15min up.

So, I was searching the internet and found this post and used your solution of the 2200uF / 10V cap on the PSU and voilá, PSU and video issues were gone.

The main and initial problem maintained, so I decided to recap the Saturn motherboard.

After recaping the picture is perfect, no video issues whatsoever, no PSU noise or problem, but now I have the most strange thing happening:

1) I cold boot the console and it goes straight to the Saturn CD player or menu...and is trying to find the disk (I have the MODE installed).

2) I tought I made some mistake on the recap of the mainboard, but keep trying to find the problem and found the following solution:

    a. If I power cycle the console and take less than a second between the power off and power on, the console boots normally to the MODE.

    b. If I power cycle the console and take more than 1 second between the power off and power on, the console goes to the CD menu and can't find the MODE / Game CD...

Any idea where should I start looking for a problem?

the recap was a success. I only had problems soldering the CE45 cap...It's really bad, but the cap is there and working (I thing).

Any help is highly appreciated.

EDIT: Also, any reason for the additional cap no the PSU to be a 2200uF / 10V. Can a use a 1500uF / 6.3 V?

Cheers,

MF