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Hi can anyone advise please? my iMac won’t start up. I have mains power to the psu and the following DC output voltages on pins 1 to 16 But nothing else picture sounds etc it’s completely dead. psu board ref ADP-310 AF B 614-0476 China Pin 1 earth pin 2 2.7mv & 1.2v when output plug disconnected pin 3 earth pin 4 11.92v pin 5 earth pin 6 1.1mv & 3.6 v when output plug disconnected pin 7 earth pin 8 earth pin 9 earth pin 10 2.8mv & 1v when output plug disconnected pin 11 11.92v pin 12 11.92v pin 13 11.92v pin 14 11.92v pin 15 11.92v pin 16 earth ps. Pins 2,6,10 dc voltages increase when DC output plug disconnected both large capacitors 300 v dc Does anybody have the wiring diagram or details of the actual figures for testing my psu before I purchase a new? Looking forward to some replies ;) thanks for your time paul Williams
Paul I,ll save you the trouble. See Diagram below. The are four diagnostic LED’s located on the logic board. The LED meanings are as follows, but if LED #1 and LED #2 are on then the power supply is OK. You can only see the LED’s through the vent holes to the left of the memory modules on the bottom of the iMac. I had to make the room completely dark to be sure if they were on or not. All of mine were off and I tested that there was power coming out of the cable and into the imac with a multi meter
LED Functions LED #1 • Indicates that the trickle voltage from the power supply has been detected by the main logic board. This LED will remain ON whenever the iMac is connected to a working AC power source. 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 source 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 and that logic board voltage regulators are functioning properly. 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 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 display, then the LCD panel, the LED backlight board, or the cables between might be installed incorrectly or need replacement.
Paul what number LED is on. ? You mentioned that you have one LED light on which indicated the PSU is faulty. I don’t think that is the case because the description for LED 1 ends with “. The LED will turn off only if the AC power source is disconnected or the powersupply is faulty.” which to me infers that the only time the power supply can be considered faulty is when ALL the LED lights are off.
