Weak IIsi Power Supply

[Byte Knight]

Hey guys,

I recently picked up a dead IIsi, recapped the logic board and power supply, and now it chimes when turned on but I get no video and the hard drive does not spin up. I measured the voltage at the hard drive power connector and I only get about 10.8V on the 12V rail, and 4.98V on the 5V rail. I don't see a pot anywhere but is there a way to adjust the power supply? Any other ideas to increase the power?

Thanks!

 

[jajan547]

To be honest iisi had probably the most unreliable and leakiest power supplies in any Macintosh. That being said I love the iisi, heck I have five. However when it comes to the power supplies in these it's best to replace them with something like a PICO Power supply, sure soft power on may not work anymore but it makes the machine more reliable, future proof, and best of all useable. Currently this is on my to do list as well but if you really want to use it right now without fixing the problem or doing the PICO mod you can simply use a iici, iicx, Performa 600, iivi, or iivx power supply.

 

[joshc]

Yep, agree with this, installing an alternative PSU in place of the original is probably the way to go with these if your unit is not reliable.

That said, the schematics for the Sony PSU are in the Bomarc sheets so you may be able to track down what's resulting in the 12v rail being on the low side but personally I'd go the modern PSU route for that one.

 

[mikes-macs]

That being said I love the iisi, heck I have five.

I have 7 of them and only 2 out of the 7 power supplies are working.

 

[bibilit]

To be honest iisi had probably the most unreliable and leakiest power supplies in any Macintosh.

I agree, should have 4 at home, probably half of them have a working PSU, spent a lot of time trying to fix those, some worked once and then no longer.
Were already underesized from new.

 

[Byte Knight]

It's unanimous - sounds like I need upgrade my power supply. Thanks guys!

 

[jajan547]

It's unanimous - sounds like I need upgrade my power supply. Thanks guys!

Provide us with the conversion process would be great to see.