I recently had a second look on a blown iMac 27'' 2011 PSU (they used the same PSU in 2009 to 2011 year 27'' models).
It is a LiteON PA-2311-02A 310W power supply (Apple P/N: 614-0446).
I tried to repair it about a year ago, but due to lack of time and the sheer amount of blown components, I just replaced it with a new one.
However, I still wanted to repair it. The fuse was blown, so I replaced it. Used a 75W dim bulb and it glowed brightly when plugged in. Next, I checked all the components, and there was lot of shorted things.
I replaced bridge rectifier (shorted), PFC diode(s), PFC MOSFET, two main switching MOSFETS, PFC driver IC and perhaps something more, but I think that was it. However, when I plugged in with a variac at 80V, the fuse blew again, however, no further damage was done. But even when I checked all the components again, I was not able to find any shorts.
When powered via a 40-600V DC bench PSU (limited at 60mA), it starts to draw excessive current when the input voltage exceeds 110V DC. As the bench PSU is current limited, the iMac PSU "pumps". After a minute or so, the PFC driver IC gets warm, but nothing else. I tried the old PFC IC and the situation is the same.
Now, I am wondering, does perhaps anyone has a schematics of this model?
What checks should I do further?
It is a LiteON PA-2311-02A 310W power supply (Apple P/N: 614-0446).
I tried to repair it about a year ago, but due to lack of time and the sheer amount of blown components, I just replaced it with a new one.
However, I still wanted to repair it. The fuse was blown, so I replaced it. Used a 75W dim bulb and it glowed brightly when plugged in. Next, I checked all the components, and there was lot of shorted things.
I replaced bridge rectifier (shorted), PFC diode(s), PFC MOSFET, two main switching MOSFETS, PFC driver IC and perhaps something more, but I think that was it. However, when I plugged in with a variac at 80V, the fuse blew again, however, no further damage was done. But even when I checked all the components again, I was not able to find any shorts.
When powered via a 40-600V DC bench PSU (limited at 60mA), it starts to draw excessive current when the input voltage exceeds 110V DC. As the bench PSU is current limited, the iMac PSU "pumps". After a minute or so, the PFC driver IC gets warm, but nothing else. I tried the old PFC IC and the situation is the same.
Now, I am wondering, does perhaps anyone has a schematics of this model?
What checks should I do further?
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