My power supply is good. Does this unit Que Fire have an indicator light? I cannot tell if the unit is getting power. I have an old IMac 10.4.11. Do not have Firewire input, but have USB. Suggestions?

Hi Joseph,

Well it's a 9 year old iMac.. it sounds to me like the power supply has failed. Nothing under $300 to fix unfortunately

A normal PC power cord fits your iMac. The kind of three connectors to the wall and three connectors to the iMac.

Possible failed video card. 3rd LED indicates MLB and GPU are communicating: (CAUTION! There is high voltage from the powersupply so any attempt to open iMac other than removing glass panel to see the indicators...should be done by authorized ACMT)

• LED 1 - Indicates that the trickle voltage from the power supply is detected by the main logic board. This LED will remain ON while the iMac is connected to the AC power. The LED will remain on even when the computer has been shut down or put to sleep. The LED will turn off only if the AC power is disconnected or the power supply is faulty.
• LED 2 - Indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly.
• LED 3 - Indicates that the computer and the video card are communicating. This LED will be ON when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the video card might be installed incorrectly or need replacement.
• LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.

Check for blown capacitors on the logic board and power supply. If you have signs of blown capacitors you will have to replace logic board or power supply.
The trick is getting the computer open. Stick a credit card in the back vent at the top of the display. Their are two tabs one and each side of the vent push forward unscrew the screws at the bottom. sit it up facing you and pull the top to you. be careful of the isight cable at the top. you will need to unscrew the LDC from the housing be careful of connected cables and check under for the blown caps.

How old is the unit? They only last so long before the battery can charge no more.

Are you sure the iMac is really shutting down or just turning off the backlight? The tell-tale sing would be to let the unit fully boot-up (wait 3 minutes) and the press the button the apple keyboard that ejects the CD-ROM. If the CD-ROM door opens, you iMac is running with disabled or broken backlight.
The inverter circuit on the iMac G4 is known to be weak.
There could be another problem, though. The iMac G4 is also known to have weak internal power supplies. Here's how you can tell:
Hold down the CMD OPT "O" and "F" keys at the same time while pressing the power button. This will tell the iMac that you want to boot into the Open Firmware shell, bypassing the Mac OS X startup. If this works, your power supply is good, the inverter is good and you have a problem with your Open Firmware boot string. To fix the boot string, Power on the unit while holding down the keys CMD-OPT-P-R to zap the parameter RAM (PRAM) and reset everything to defaults.
If you were not able to boot into the Open Firmware shell, your problem is either a failed power supply or a failed screen backlight. The last possible culprit is your iMac could suffer from "Bulging Capacitor Syndrome", where a batch of iMac G4s, iMac G5s another electronics were fitted with a bad batch of capacitors. Eventually, the caps will rupture and cause irreparable damage to the logic board. Only way to verify this is to pull the unit apart and visually inspect. If you see little green or blue cylinders that seem to be bulging or oozing a thick oily goo, that's your problem. Only recourse is to shop around on eBay and look for a replacement logic board.

Assuming you have the model with four diagnostic LEDs, the lack of LED-3 indicates that the computer and the LCD display are NOT communicating. This LED should be ON when the computer is turned on and video signal is being generated.
The first solution is to reset the PRAM (hold command-option-P-R after the boot chime until you hear another boot chime). If video does not appear, then power down the computer and reset the SMU by pressing the SMU button ONCE ONLY. (The SMU button is located just south of the fan housing and is the button further away from the fan; the other button is a power button.) If this does not fix the video, the next step is to remove the optical drive. If this does not fix the video, put everything back together and attach an external display using the dongle supplied with the unit. If the external display fails to work, you have a logic board problem; otherwise, you have an LCD panel, inverter, or cable problem.

Thanks for contacting FixYa Support.

I have repaired numerous iMac G5 17" models for a while now and because I have, I can tell you just from the symptoms you have described, this is potentially a power supply issue.

However, the iMac G5 17" have been known to have swollen capacitors, which can also ultimately impact the power management / performance of your iMac.

If you are able to, very carefully and don't touch them, you can look on the iMac's main logic board to see if you notice any swollen capacitors. If you are not sure what a capacitor looks like, they look like mini batteries connected to the board.

Should you do this and find that the capacitors are ok, then I would recommend for sure, that you look into replacing the power supply.

For your model of iMac 17" provided it is not an Intel-based iMac, the part number you will need to source is part# 661-3627. Below, I have also provided the most inexpensive price for this iMac power supply per this link:
AppleComponents.com

You may find even lower prices for this iMac 17" power supply, if you search online further, but this is one of the better online Apple components vendors. Therefore you should be able to see and compare the prices on this website, with some of the other vendors
advertising the same Apple power supply for the iMac 17".

I hope this helps. If you have any more questions on this subject, simply reply back to this post.

Best Regards,

-Mactechtrainer

Okay, you probably need a new power supply, this unit had many power supply and logic board problems.  300.00 is a lot for a power supply, 120.00 is the usual cost plus 50.00 labour, and that is canadian dollars, it should be much cheaper if you are in the U.S.

try powering the unit right down by disconnecting from the mains supply. fire up after 5 mins and see what happens. There is a separate transfomer for the standby supply(small red light) An internal fuse may have failed or the thermal fuse inside the transformer. If fuses blow as sson as you fire up = output transistors hay be short circuit.