iM 4,1-14,4 Looking for schematic diagram of 27" 2009-2011 iMac power supply, PA-2311-02A (liteOn)

[USB3foriMac]

does anyone know how the I 219A & EMC1404 circuit works? I have a ADP-310AF PSU with both of them blown [VS & Gnd are shorted], along with a blown TL432 (with marking T4DS)[cathode & anode shorted when chip is on the board but Cathode & VREF is not shorted to ground when chip is removed].

Right now the imac will blow high speed fan due to this. Would it be ok if i just change all 3 chips?

That's for power and temperature monitoring. I wonder why they died; Would have to be a surge on the secondary side.
Since your supply still works, I'd replace the defect parts. If we assume there was an overvoltage on the secondary that killed these parts, other ICs (if any, I didn't check) may have died as well. Better check. It would be normal that the fans spin up because of missing temperature monitoring.

 

[protocold]

So, I have changed these 3 ICs (TL432, I 219A, EMC1403) and the fan remain high but when I ran ASD I saw some sensors problem was corrected except Tp2H.

Upon further tracing I saw 2x 10 ohm resistor connected to EMC1403 was blown opened along with blown temperature sensor Q132 (which is a 2N3904)[which is the corresponding Tp2H]. I have replaced all those and voila... PSU back to normal and the fan no longer blow high speed.

Hope this would help those who encountered similar situation.

 

[Lupotto solitario]

I have an imac pa 2311-02a power supply like yours faulty no output voltage on the rectifier bridge 310 volts; and on the c48 there is a fluctuating voltage ranging from 14 to 8 volts please what components could be compromised.
I disassembled and checked
Q1 and Q3 = Ok
Q6 and Q2 = Ok
and many other components but i can't figure out which part of the circuit is not working thanks

 

[hibananoe]

The FET is 6R199P (IPA60R199CP). You can leave both the diode and the FET out, these are for power factor correction. If this is your only fault, the supply will work without these components.
There are several cases here where this indeed was the only fault. Make sure the primary FETs are not shorted, and the rectifier is ok. If so, you have good chances that it will work. If so, I wouldn't bother to replace the component. It's for the benefit of the power company and to protect their wiring.

Today I finally replaced the FET - I already had ordered them so I decided to use them. This was the only fault, so I only had to replace the input fuse. And it worked! My iMac is back to life thanks to this valuable threat. Thanks a lot!

 

[protocold]

This sounds more like a bad capacitor. You can inspect visually, but maybe one of them or several simply dried up. You can replace them, that should help more than soldering on resistors.

So after more than 18 months I decided to give another try.. I swapped all capacitors and it is still not working.

However, I happened to find a blown resistor marked 3304 that went open around NCP1605G, after replacing it the PSU is working!

But still, there is still awful noise coming out from this PSU...

 

[allenkim]

Hi?

My MAC also had a blown fuse. So I ended up reading this thread and I found the Boost FET was shorted. And the T4Y4 diode connected to Pin16 (HV) of NCP1605 was also blown. Due to a work mistake, Pin7's Ct capacitor was also lost by the heat gun. If you could see the circuit diagram, could you tell me the part names of the two components?

1. Ct part name : according to reference schematics for 300w ( it has 4.7nF or 8.2nF )? I calculated this FET On-time but I guess it is very small value...so I want to know correct.

2. Part name of T4 diode coming into HV? (From Google search, T4 appears to have too low voltage.)
- marking T4 is 1N4148WS SOD323 ? it has only 100V maxium peek.

 

[countryhick]

My mid 2011 27 imac would not start one day, psu is "pa-2311-02a"
No power whatsoever on connector to mainboard, no light on diagnostic leds.
Looks completely dead.
Fluctuating voltage in secondary circuit (7-14V) as some others here have said.
Tested various smd components, found one 10 OHM resistor way out of spec. Replaced with standard through hole resistor, as it was the only thing I had at hand.
Images attached.
Powered up straight away.
Happy days.
Hope it can help somebody.

FIXED
I've got a Mid 2011 27" iMac with an identical fault... I checked that same 10 ohm resistor on my PSU.. and it was reading something like 240 Megaohms.... Replaced the surface mount resistor it in a similar fashion to yourself, and the PSU fired back to life!!!! Thanks a ton everyone who's contributing!


**** Couple of extra notes and observations.

Machine had been working completely fine with no abnormal signs of the PSU starting to fail... It just became totally unresponsive when trying to turn on one day.
All diagnostic LEDs on the mother board remained off under all circumstances.
A multimeter check of the outputs on the PSU showed no activity whatsoever.

 

[hmsahir4u]

My mid 2011 27 imac would not start one day, psu is "pa-2311-02a"
No power whatsoever on connector to mainboard, no light on diagnostic leds.
Looks completely dead. The only voltage are on the mains capacitors. Please guide me checking steps to diagnose the problem. I know that there is no burnt component because some times it is become in working.