I've got a newly acquired Perform 550 for use with my IIe card however I just picked it up from its Orignal owner (he paid 2400 new for it) I paid 50 with everything he just wanted it to have a good home. Not used in a year fine when put away. But now I put it in and flip the rear switch and I hear the monitor energize really quick but nothing else. I push the keyboard power switch I add New PRAM battery, I toggle the power switch on the rear many times. I remember that the LC AIO series had some issue with this that wasnt a biggie but I don't remember the problem. Since it powers the monitor (charges it) I don't think it's the psu.
Ideas?
The power switch on the rear won't turn the computer on. It's like the power switch on the PSU of a desktop PC -- just leave the switch on all the time. It's the power key on the keyboard that you'll use to turn the machine on. Press and hold the key for a second and, if you truly do have a good PRAM battery in there, the machine will boot. Otherwise, you have either a bad keyboard, motherboard or analog board (which includes the power supply circuitry).
Yes I tried the keyboard switch too and nothing the PRAM battery is new. And I tried 2 other known good keyboards. When plugged in and the power button on the rear is turned on the screen energieses to I really don't think its that. Was there another trick on these only reason I ask is because I had one in the 90s and remember power issues were very common and not serious
I am no expert on old-world Macs however here is my advice:
1.Check CPU (I have seen plenty of machines not start because of a bad CPU!)
1b.Replace CPU
2.Check RAM (not seen too many machines not boot because of this but anyway)
2b.Replace RAM
3.Check PSU, Is it known to be good or is it of unknown condition?
3b.Replace PSU
4.Check Internal Drives (seen a machine go bad because of one dodgy drive)
4b.Replace Drives
5.Check Capacitors. Too many good Macs have gone to the dump because people skip this step. 2 out of 3 times replacing bad capacitors will fix the machine.
5b.Wash Mainboard
5c.Replace Capacitors
Just my 2c!