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Old 11-21-2018, 08:47 AM   #1
ced1298
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Default Imac A1418 820-3302-a need help NO POWER

Good day everybody , i have an imac no sign of power on the motherboard
- Powersupply has 12V an 3V present but the main logicboard doesnt show any 4 LED lights. hoping someone could help me where can i get a diagram and board viewer on this particular model 820-3302-a much appreicated.
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Old 11-21-2018, 11:21 PM   #2
mcplslg123
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Default Re: Imac A1418 820-3302-a need help NO POWER

schematic and boardview. Hope it helps.
Attached Files
File Type: rar 820-3302.rar (1.80 MB, 178 views)
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Old 03-15-2019, 10:31 AM   #3
drewski87
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Default Re: Imac A1418 820-3302-a need help NO POWER

Does anyone have a schematic that shows Q4500 init??? all that i get doesnt show this mosfet... 820-3302-A
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Old 06-22-2019, 07:00 PM   #4
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Default Re: Imac A1418 820-3302-a need help NO POWER

Hi, I have an A1418 8203302A with exactly the same symptoms , did you find and fix the fault? hope you can help thanks Bruce
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Old 12-15-2019, 11:31 PM   #5
Sergio Kub
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Default Re: Imac A1418 820-3302-a need help NO POWER

Thank you very much. With the help of the The Bad Cap Forum I got the schematic and solve the Imac 1418, board 820-3302.
Only the first diagnostic led was on.
I researched and noticed that was missing source 3.3V S0, IC U7900 was very hot and found short on the out (PP3V3_S0_FET). I applied 3.3V voltage to pin 8 and found that C4100 was heating up. Did the replacement and computer ok.

Last edited by Sergio Kub; 12-15-2019 at 11:41 PM..
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