Chosen Solution
Suite à la question iMac ne s’allume plus Bonjour pour faire suite à ce tutoriel, j’ai quelques questions avant d’investir dans du matériel. J’ais suivi la marche à suivre décrite. Soit. Enlever la câble secteur et appuyer20 secondes. Allumer le Imac et tenir le power on 10 seconde (pas de réactions des ventilateurs différentes de celle décrite plus bas) Contrôler le voltage sur l’alimentations 12V OK 5V Ok. Led N°1 allumée seul à la mise en marche. Symptôme les ventilateurs tournent deux secondes et s’arrêtent et recommence ce cycle. Pas moyen d’arrêter la machine sans débrancher le câble secteur. Précision Imac A311 EMC2428 Alors Carte mère ou alimentation ??? merci de votre aide iMac does not turn on anymore Hello, I followed this tutorial, I have some questions before investing in the parts. I followed the procedure described: Remove the mains cable and press 20 seconds.Turn on the iMac and hold the power on 10 seconds (no fan reactions different from the one described below)Checked the voltage on the 12V OK 5V connections on power supply.LED # 1 lit only when switched on.Symptom the fans turn for two seconds and stop and start again this cycle.No way to stop the machine without disconnecting the power cable. iMac A311 EMC2428 So is logic board or power supply ??? Thank you for your help Mise à jour (10/09/2018) Motherboard changed, Imac OK. I just would not want to buy a power supply that was OK. Thanks for your help.
Replace the power supply first. Here’s how: iMac Intel 21.5" EMC 2428 Power Supply Replacement 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.
I went mad with the same problem for days and tried everything I saw on forums but wouldn’t work with me. One day after many tries I plugged the external sound card onto the computer and switched it on, the light on the sound card went green which meant it was taking the power from the computer, I pressed the start button on the computer and it worked immediately. I wonder if it would work with other peripherals which take the power supply from the computer. The only “problem” is that I have to start the computer with the external sound card plugged in but after the computer starts I can disconnect it if I am not using it. My imac is a late 2009 so I won’t care to have it repaired when I can start it this way. I hope it will work with you. Cheers from Spain
