Help! Mac G4 (mirror doors) hard to turn on!

[visvaldis]

My Mac G4 (mirror doors) works fine and I appreciate it. Lately, the machine is difficult to turn on. I press the button, the light briefly flashes, nothing happens. I pull out the power cord from the socket, put it back in, press the button, the light briefly flashes, nothing else happens. I go through this process several times (in about 30 minutes), and finally the Mac starts and other than the date and time must be reset, everything works as normal. For 2-3 days the Mac will turn on without problems. But then again, it becomes difficult. The battery is about 10 months old.
I suspect it's the power supply. The local Mac authority shop will not do it, because Apple no longer makes power supplies for my vintage Mac. Trouble-shooting and repairing Mac problems are new to me. I found a supplier that sells the required power supply for $250. Before buying I'd like to make sure that is the problem.
I appreciate all help, suggestions, and advice.

 

[Tyroler]

Welcome.
first.Even a Baby can die
but if its the PSU thers just 2 Inch down a discussion
Found that Link there
http://dl.dropbox.com/u/1020076/jj/mddpsumod.html
Its not a good Idea to put a new PSU in Place without converting the Cables

 

[zen.state]

If it ever starts up then it's not the PSU at all. Not sure what logic Tyroler is using here.

Try this:

1. Power the MDD down

2. Remove the logic board battery and leave it out for 10-15 min.

3. Put the battery back in and press the PMU button just once.

4. It should startup fine now.

To me this sounds very much like a sketchy PMU that needs to be reset. They can easily crash themselves at times and will also crash if you press that PMU button more than one. You want to do one good press where you hold it down for about 1 second and then release.

The PMU reset button location is circled in the image below:

 

[Nameci]

How about replacing your PRAM battery?

 

[visvaldis]

I forgot to mention...for the last several weeks I have been turning off the Mac MDD by pulling the power cord from the wall socket. Previously, when clicking 'shut down" in the apple menu, the start next day was problematic.
I wonder if doing this led to the current problem.
Thanks for the info. I will try pulling out the battery and leaving it out for 15 minutes. I will remove everything from the back; USB printer cable, sound output, etc. and pull out the power cord.

 

[zen.state]

You should never turn off a computer by just pulling the plug. Thats asking for data loss and/or corruption and also is bad all round over time on electronics to keep doing it.

A much better way to power down without shutting down with the OS is to press and hold the power button and 3-4 seconds later it will power down on it's own. If it was me I would keep it running 24/7 and reboot every couple days to keep things fresh.

 

[DJLC]

How about replacing your PRAM battery?

This. I've had this exact issue, and a new PRAM battery fixed it for a while. Eventually the PSU gave out, though, so ymmv.