Imac 27 Repair

[Svoy]

Hi guys,
Could you please help me to find out this one:
http://i1212.photobucket.com/albums/cc456/Svoy/IMG_0208_zps97ddd7f0.jpg
It is from Imac 27 (mid 2011) power supply, it blows the fuse every time when I plug in, so on closed inspection I found out that these capacitors have cracks...
I would really appreciate for the help
Thank you in advance.

 

[(*steve*)]

I would check that you don't have shorted rectifier diodes (presumably there's one just near that capacitor) or more likely the main switching mosfet.

The capacitor *may* be damaged, but is unlikely to be the cause for repeated fuse blowing.

 

[Svoy]

I would check that you don't have shorted rectifier diodes (presumably there's one just near that capacitor) or more likely the main switching mosfet.

The capacitor *may* be damaged, but is unlikely to be the cause for repeated fuse blowing.

Hi,
Thank you for reply....
So, I am going to test all the diods, but what about "the main switching mosfet"? Could you please tell me which one?

 

[(*steve*)]

Find out what the part number are on the devices on heatsinks 3 and 4

 

[Svoy]

Find out what the part number are on the devices on heatsinks 3 and 4

Hi *steve* I really appreciate for your help....I found out the number on the devices on heatsink 4 its K10A60D and heatsink 3 K20A60U

 

[(*steve*)]

OK, a K10A60D is a 600V 10A mosfet. I would check the datasheed for that, and measure the resistance across the drain and source (both ways).

And the K20A60D is a 600V 20A device. Check the same for this.

Note that you need to ensure that the capacitors on the board are not holding a charge or you could (a) damage your meter, or (b) give yourself a very uncomfortable shock.

Having two different devices like this seems to suggest that there are actually 2 independent power supplies on this board. Perhaps there is a standby as well as a main power supply, or perhaps the different voltages are on independent supplies?

 

[Svoy]

Than you *steve* for your help....but after all I decided do not mess around with Power Supply for machine $2000 ....I just bought the new one....
Thank you anyway