I have not located any shorts and the Q7660 and Q7610 mosfets seem to be fine. I then tried to remove the U7600 controller, but I'm afraid my tools are no good.
After a long time with the heat gun at its maximum temperature (theoretically 480 degrees), I have not been able to desolder it....
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I have found that PP3V3_S5_REG delivers 0.0075V, and 1V05 practically 0v.
When examining the VIN input on U700 (ISL6237) I check that 3.1V arrives, which does not make sense, since the datasheet indicates that the input voltage range is between 5.5V and 25V.
As the power supply is received from PP12V_S5_REG, it passes first through the resistor R7650 (2.2 ohm), I remove this resistor and it measures more than 100 ohm, so I replace it with another one of the correct value.
At this point, now the output voltage is no longer 3.1V, but 11.8V, but then I notice that the ISL6237 circuit...
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trying to repair imac motherboard model A1311 (late 2009)
Hello everyone,
Some time ago I acquired an imac computer model A1311 that does not boot (motherboard ref. 820-2494-A).
The power supply is working properly (I have two), it delivers the 12V on pin 4 of the power connector (PP12V_S5).
As I have the schematic diagram and the boardview, I have made a series of measurements, obtaining the following results:
PP12V_S5 -> 12V
3V3REG_VCC -> 3.12V (something low?)
PP5V_S5_LDO -> 0.02V
3V3REG_VCC -> 0.0066V
I have also measured the resistance to ground on the coils, and I can't find...
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Hello everyone, my name is juan antonio, I am a computer scientist by profession, but I have always been fascinated by the world of electronics.
In my spare time I build circuits for my projects, and I also like to repair broken equipment and devices.
My knowledge is quite limited, but I do not lose the illusion to continue learning to better understand this exciting world of electronics.
greetings from palma de mallorca.
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