Imac 24'' (A1225?) PSU bad?

[Chron-O-John]

Hi,

I have an Imac (not quite sure about the model) which does not start. When I turn it on the fans start spinning but there is no picture or start sound.
Diagnostic light 1 & 2 are lit.

I suspect the Power supply (PA-3241-02A1). It has no visibly damaged parts, but I measured the output and the voltages (under load) seem a bit to low to me.

Unfortunately I wasn't able to find an exact pinout, but I measured 11.8 and 2.6 Vols on some pins.

From what I read there should be 12 and 3.3 volts.

Any suggestions what the culprint could be before i start to desolder all FETs and Caps (well most of them could stay in circuit) in order to measure them.

Thanks for your help!

[stj]

Re: Imac 24'' (A1225?) PSU bad?

did you check the battery first? just wondering.

[Chron-O-John]

Re: Imac 24'' (A1225?) PSU bad?

you mean the Cr2032 battery?
Should be OK. Has 3.05 volts.

[tester272001]

Re: Imac 24'' (A1225?) PSU bad?

How about pull the battery and do a PRAM reset ? Those old mac has a reset button.

[Chron-O-John]

Re: Imac 24'' (A1225?) PSU bad?

already did that, unfortunately no success

[stj]

Re: Imac 24'' (A1225?) PSU bad?

lets see some psu foto's then

[Chron-O-John]

Re: Imac 24'' (A1225?) PSU bad?

Thanks for your replies so far, here are some pics.
I already measured all Caps in circuit using an ESR-Meter. All of them seem ok to me (in fact they have a suprisingly low ESR)
ESR is between 0.02 and 0.8 depending on Capacity and rated voltage.