View Full Version : Mac 7300 Power Supply problem and Question

07-02-2001, 06:34 PM
Wondering if someone could verify that my thats 7300 power supply is dead.
When I try to power up the power supply makes a faint clicking sound, also
notice that the green power led in the front would briefly come on at the same time.

I've checked the battery to make sure it was not the problem.

If it is the power supply, then i want to replace it. But can someone also tell me if the 7300 power supply is different from the other Mac like the 7200, 7500, 7600. I've checked the power supply on a 7200 and it is two pins short at one end. Thanks in advance.


07-02-2001, 08:17 PM
How did you check the battery? A no load voltage check is not sufficient unless the voltage is less than 3.6V DC. Then you know it is no good. k

07-02-2001, 08:55 PM
I removed the battery from the MB and tested it, I guess this is what you mean by no load. It did read 3.693 to 3.694. How do I test it under load? I have four Mac here that take similar battery.


07-02-2001, 10:35 PM
An easy indicator is if you take the power supply connector and disconnect it from the motherboard. Then take a voltmeter to it. "Plug" the black (negative) of the meter into a black socket on the power supply connector cord. Then touch the red (positive) end of the voltmeter to the yellow wire on the power supply connector. With your voltmeter, you should get a reading.

Now, this is assuming that the power supply is plugged into a good outlet and the voltmeter is set to read DC volts (about 5V).

About checking it with a load....I would assume the easiest way is to leave everything assembled and setup the voltmeter on the battery ends. Try to startup and see what voltage the battery is pushing.

Does it make any difference if the only powered thing attached is the mobo? All the PCI cards and drives out and disconnected, that is.

07-02-2001, 11:53 PM
Because of Kaye and Dogstarman insistant pointing to the battery as a culprit. I decide to measure the battery voltage on startup like Dogstarman mentioned. It was only pushing 2.54 volts under load a quick exchange of battery from an 8600 and she is running again!

I learned from Kaye measuring voltage with no load is not sufficient unless the voltage is less than 3.6V

And from Dogstarman how to wrench inside your mac like a pro.

Thanks again for the help!