3DO doesn't work, there's a buzz in the power supply (FZ10)

[unsurreal]

I've got some knowledge in electronic stuff (not enough it seems ) so I've opened the console to see what could be wrong.

This buzz is high pitched when I connect the power supply to the main board and low pitched when I disconnect it...

Does anyone knows what voltages this power supply provides?
When I measure the output pins I read only very low and oscillating voltages (most below 1V)

Any help will be extremely appreciated.

[DrKilljoy]

I'm not sure what the output voltages for an FZ-10 are, but it sounds like you've got a problem with a capacitor or transistor. Try metering it out and see what you can find.

Typically, in computer power supplies, a whine like what you described is related to a faulty transistor (which may in turn be bad due to a connected capacitor that went bad).

[unsurreal]

Thank you a lot.

A friend of mine and me were trying to figure out the problem yesterday.
The main transistor (the one with the heat sink) is probably ok (not opened or short-circuited) as well as the capacitors.

It seems that some diodes have a leak problem, we'll try to replace them with a similar value (if we find it for selling around here where we live).

All we can do is keep testing and replacing parts until it works and keep looking for the voltages so, at the worst of possibilities, we build a simpler power supply with the same voltages and current capabilities

When (if) we're done, I'll certainly post the proccess somewhere to help others with similar problems.

Its an anguish that I don't wish to my worst enemy.

[DrKilljoy]

I'm glad that you may have found out what the culprit is. Post back with the results either way. By the way (since you've got your FZ-10 already open), you mind helping me out with my resistor problem in a nearby topic, would ya? I just need to know that value for R733. Thanks and good luck with your system.

[DrKilljoy]

I went ahead and measured those output voltages for ya. I took the readings from the power board side (the orange/tan board). There are 18 pins total:

Pins 1-3: 8.69V (~9V)
Pins 4-12: No reading
Pins 13-17: 5.08V (~5V)
Pin 18: No reading

Hope this helps!

[unsurreal]

Thanks!

just one thing... did you measure these voltages with the power board connected to the main board?

I think that the real voltages it outputs are read with it disconnected, or not?

[DrKilljoy]

I think that the real voltages it outputs are read with it disconnected, or not?

I think that's how it goes; at least that's the way I did it. I took the ribbon out first before measuring.

[unsurreal]

ok then

Thank you again

[unsurreal]

kinda funny and kinda embarrassing...

the problem was not in the power supply after all.

The power board does a little buzz normally when its not connected and when its short-circuited this buzz becomes high pitched and louder.

so my friend and I concluded that it should be something on the main board
and it was...
I don't remember the part number of this component right now, but it is an electrolytic capacitor very close to the RAM ICs, and the value is 100uF X 6,3V.
It was completely smashed (I don't really know why, maybe I did it myself and didn't notice).
So we just had to replace it.

Anyway, this wasn't a total waste of time (and energy), we understand now how the 3DO power supply works, and will post it here some day soon, so maybe we can help someone that actually has a problem there...

What matters now is that I'm happy I can play Road Rash and Gex again =D

Thank you again for the support

[DrKilljoy]

Glad to hear you got it working again. It's funny how electronics work sometimes...

If you ever pursue it further, it would be interesting to see how that power supply operates.