Need Help with Sony CR-44 Power Supply

[jdmcs]

I have two Macintosh SE computers, both have Sony CR-44 power supplies. I have recapped one of these supplies with a kit from Console5.

Both power supplies are exhibiting the same issue: the 12V output is measuring nearly 12.8V, which is definitely out of spec and is causing artifacts on the screen.



Meanwhile, the 5V rail is reading 5.08V…

So I discovered that there is an adjustment potentiometer in the power supply, and I tried adjusting it while under load (using an ATX extension cable). When I adjusted the power supply to 12V using this adjustment, the 5V rail was an unacceptable 4.2V. But as soon as I got 5V back into spec, 12V was was out of spec (high) again.

This seemingly indicates that I have a faulty component in the power supply that I tried to adjust. But I’m no power supply expert, and I haven’ta clue where to begin.

Also, please contain this thread to repair suggestions only. I realize that I could install an ITX power supply in the Sony CR-44 and call it done, but that’s probably outside my budget right now… especially since I have two power supplies that are both malfunctioning.

 

[retr01]

Hi @jdmcs!

Recapping the CR-44 is all that is needed. If adjusting the voltage and you see it going out of specs, have you tried readjusting to see if you can bring it within specs? I am unsure if a component has a problem because you recapped the CR-44.

As soon as you readjusted, the voltage shifted to above 12v when the 5v rail was within specs or vice versa. That is odd.

@JDW, do you have any thoughts about this particular dilemma?

 

[retr01]

@jdmcs, have you checked the analog board's solder joints? Those can crack and cause issues. Reflowing is the usual recommendation.

Low 12v line Macintosh SE - Sony CR-44 PSU

Hi everyone, I am currently restoring a Macintosh SE FDHD. I have recapped its Sony CR-44 PSU. The end of the recapping operation is to set the output voltage. The 5v line works perfectly, I have set it to 5.3v. However, I am really worried about the 12v lines. The first one (red cable)...

forum.vcfed.org

 

[retr01]

Another thought I have is setting the 5v rail to 5.5v without any load to the PSU and seeing if that balances out 5v and 12v rails, as the guy in the above VCF thread discovered.