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Old 09-30-2017, 04:28 PM   #1
thevolt
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Default iMac A1311 PSU 614-0444

Hello, I am hoping someone can point me in the right direction in fixing the power supply on my mid 2011 21.5" iMac (A1311). The onboard diagnostic LED lights 1 and 2 do not light up when plugged in and powered on. The iMac turns on but does not get passed a black screen. For the past year if turned off the computer would not boot up unless I unplugged the power cord for a few hours. This past week I was updating to 10.13 Sierra and it shut down and will not get passed a black screen now. I pulled the PSU, but everything seems to visually look clean. Attached are some pictures. I really don't feel like buying a new PSU for almost $200 on a computer I do not use very much. If anyone has had an experience in dealing with these PSU's and can pass on any suggestions I would appreciate that. Thanks in advance. -Jay
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Old 10-02-2017, 12:23 PM   #2
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Default Re: iMac A1311 PSU 614-0444

The 5 capacitors are KZH 1500uf 16v. Should I start by replacing those 5. Is there any suggestions for a better brand of that style of capacitor? Or should I be looking somewhere else on the PSU?
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Old 10-02-2017, 04:59 PM   #3
PeteS in CA
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Default Re: iMac A1311 PSU 614-0444

I'd look into whether or not it has the equivalent of a 5VSB or 12VSB. If it should but does not, that is where your problem is rather than those output capacitors. If you have no standby voltage, look at small lower voltage electrolytics on the primary side.
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Old 01-31-2019, 10:40 AM   #4
patrik1998
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Default Re: iMac A1311 PSU 614-0444

Salve ho la stessa scheda che si accende la iMac ma dopo 10 minuti si riavvia,quando mi arrivato era completamente spento c'erano due resistenze e due condensatori smd, li ho cambiati ma ora accende ma si riavvia potrebbe essere che il valore dei condensatori sbagliato? Sapete i valori di questi condensatori? Sono c009 e c010 grazie mille
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Old 02-01-2019, 08:42 AM   #5
patrik1998
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Default Re: iMac A1311 PSU 614-0444

"Hi help I need to fix an iMac with the same PS board, damaged by a lightning strike. When I opened it, the board wasn't working at all: I replaced two burned SMD resistors and two capacitors, and the iMac came back to life. But after a short time it became to shut down and restart by itself... I guess I misread the value of some burned component, replacing it with the wrong one(s). Can you please . me? They are R003, R004, C009 and C010. Many thanks in advance!"
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Old 02-22-2019, 11:44 AM   #6
Siddig
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Default Re: iMac A1311 PSU 614-0444

I have problem in same PS board . I have change it burn big capister . I get 2v in 12v pin.
Can you help me
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Old 09-19-2019, 10:03 AM   #7
sena_akutsa
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Arrow Re: iMac A1311 PSU 614-0444

Quote:
Originally Posted by patrik1998 View Post
..." Can you please . me? They are R003, R004, C009 and C010. Many thanks in advance!"
R003 "331" = 330 ohm
R004 "331" = 330 ohm
C009 = 25 nF
C010 = 25 nF
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