3DO FZ-1 No Power - suspected PSU

[Brik_1111]

PHOTO'S HERE

Hi all, apologies for the lengthy post but there’s a bit to explain.

I recently received a broken FZ-1 that won’t turn on. From what I can tell, at least two others have been inside before me, which is never good. The power cable had been previously cut, with the copper simply twisted together and held with electrical tape.

Capacitors 1, 35 and 36 had been replaced but with substandard soldering. While the pads were connecting to where they needed to go, the solder was dull and bumpy. Additionally, D2 was missing completely with R2 extremely corroded.

So, I got to work properly repairing the power cable, soldering the copper together and covering the breaks with heat-shrink. I redid the caps even though there was continuity, replaced R2 and also D2 using a modern replacement suggested on this Russian forum (eighth post from the bottom).

As you can see in the photos, the positive pad for C36 is a bit destroyed. There’s still continuity, however. At this point, the console still wasn’t turning on, so I started reading the service manual and technical guide. Following the flowchart on page 5-2 of the technical guide, I determined that the power switch was shorting as it’s supposed to when on/off and that the fuse was good.

The next section of the flowchart asks if AC 10-18V is being outputted to both CN1 terminals – and it turns out that’s not the case. I measured only AC ~0.23V on both. Is this the smoking gun? I’ve never worked on a 3DO before. In fact, I’ve never checked AC on anything. I simply switched my multimeter to AC mode and checked the pins on CN1 while holding the negative probe to ground. Is that the correct procedure?

On further chat with the guy who gave me the console, he thinks 240v may have been put through the system before he got it since we’re in Australia (the console is American). What does everyone think? Could it be that the PSU is rooted having had 240 put through it? Is there another way to check it besides from CN1? And if it is, does anyone have experience replacing these? I read this thread that talked about replacing the 110v one with a modern 240v equivalent. I should add that I’m of course testing with a step-down transformer.

Alternatively, could the problem be something I’ve missed completely? Any input would be appreciated. Cheers.

[Taijigamer]

Did you check the 2 pins on the transformer output (probe to pin, not connected to board)? If it’s still low voltage it sounds like a problem with the secondary winding inside the transformer. In which case check that other thread for recommendations for replacing the transformer.

[Brik_1111]

11 hours ago, Taijigamer said:

Did you check the 2 pins on the transformer output (probe to pin, not connected to board)? If it’s still low voltage it sounds like a problem with the secondary winding inside the transformer. In which case check that other thread for recommendations for replacing the transformer.

Do you mean any of these two connectors disconnected from the board? Where do I probe for ground? Excuse the ignorance, I don't have much experience with AC.

[Taijigamer]

That’s correct, probe both pins on the blue connector (+ on one pin and - on the other). If the transformer is working, you should get 10 - 18VAC. If it’s lower than 10 VAC the transformer is faulty and needs replacing.

[Brik_1111]

3 hours ago, Taijigamer said:

That’s correct, probe both pins on the blue connector (+ on one pin and - on the other). If the transformer is working, you should get 10 - 18VAC. If it’s lower than 10 VAC the transformer is faulty and needs replacing.

Confirmed, less than 6v measured. Guess I'm buying that replacement from the other thread. Can offer any tips for wiring this? Looking at the spec sheet, which tabs do the blue and red wires connect to?

[Taijigamer]

Sorry, just checking you probed the voltage between the pins (blue connector) and not between each pin and ground (red connector). 
 

What voltage does your region use, 110V or 240V? 

[Brik_1111]

6 hours ago, Taijigamer said:

Sorry, just checking you probed the voltage between the pins (blue connector) and not between each pin and ground (red connector). 
 

What voltage does your region use, 110V or 240V? 

Yep, just probed the blue connector with a probe on each pin. We're 240v here in Australia, but I've been using a step down transformer so far for testing.

[Taijigamer]

The data sheet says to connect your mains cable to pins 1 & 5. Connect 2&4 together. On the output, connect your blue connector cable to pins 6 & 10. Connect your red cable to pin 8.

 

https://imgur.com/gallery/a0AdRrn
 

 

[Brik_1111]

34 minutes ago, Taijigamer said:

The data sheet says to connect your mains cable to pins 1 & 5. Connect 2&4 together. On the output, connect your blue connector cable to pins 6 & 10. Connect your red cable to pin 8.

 

https://imgur.com/gallery/a0AdRrn
 

 

Thanks Taijigamer, you've been a tremendous help. I'll order one in and report back once it's installed and (hopefully) working.

[Taijigamer]

No worries. Good luck.

[Brik_1111]

Quick question: Does it matter which specific wires of the blue connector go to pins 6 and 10? Either way around is okay?

[Taijigamer]

Either way around is ok ( same for the input side). It’s AC voltage at this point and swings between negative and positive. Once it leaves the transformer, the negative voltage is converted to positive voltage in the bridge rectifier. https://www.teamwavelength.com/power-supply-basics/