Search results

IT'S OK! After reviewing the soldering of the U7100, I have both VCORE and AXG, and the chime once again! As a conclusion, there were two problems: 1) U7100 was not working; 2) The techs before me installed an invalid BIOS. I hope it's done! Thank you for your help.

I managed to make VCORE work. Replaced U7100 again. The board lit LEDs # 1, # 2 and # 3 and chimed. I was happy because I believed it had been fixed. But after putting it to work on its own power supply and using the power button, it is again only turning on LEDs 1 and 2. (By the way, this...

I tried to read the U7100's PWM outputs, but found plain voltage. Now I don't have VCORE anymore. (???) LEDs 1 and 2 are still on. The new BIOS was outsourced, I can't be sure if it is really good (should be). Do you have this BIOS file?

VCORE is there, but I found AXG is not. With the original BIOS I've got LED # 2 flashing again.

Hello. I replaced U7100 and the BIOS. Now I have LED # 1 and LED # 2 on. The board is consuming 1.25A. I don't have LED # 3 on. Tried with and without memories installed. This board has the GeForce GTX 680MX with 2GB. I need advice, please.

I don't know if that helps, but I talked to the owner of the iMac and he told me that the computer was sent to an assistance before, because it had stopped working once before this, and at that time the repair was done at the bios. He told me also that he took the iMac to that assistance again...

I think all the big coils are listed above. VRM coils are not pulsing. What is the next step?

L7610 fixed 3.3v Pulsing at same time: L7200 10.5v L7710 1.4v LB710 1.4v LB720 1.04v LB400 10.2v LB510 0.8v LB530 0.8v LB550 0.8v LB650 0.8v L7650 5v L9840 10.2v L9860 11.2v L9820 11v Not pulsing: L7210 0v L7230 0v L7250 0v L7310 0v L7330 0v

This is the first iMac I work on. Any guidance will be highly appreciated.

PPVCORE_S0_CPU is not being generated. I tested the U7100 and the pin "VR_RDY" (PM_PGOOD_REG_CPUCORE_S0) is being pulled low when there is the pulse of energy on the rails. According to its datasheet (ISL6364), I understood that it would be an OVP or OCP event. In its PWM outputs, during the...

Finally the MOSFET Q7950 has arrived. I replaced the original part and the board continues with the same behavior: LED # 1 on, LED # 2 flashing on and off. The original part has no corrosion on its pads.

Q7950 is a metal case version. Before messing with the FET I made some captures on the oscilloscope showing the operation of Q7950. As I had answered before, the capture shows that at the same time when FET_EN_P12V_S0 pulses near 22V, PP12V_S0_FET pulses 12V.

I have feedback. I received the new processor and before testing it on the board under analysis, I tested it in a PC setup to make sure it was in good condition. This test being good, I removed the resistor R6903 and installed the new CPU. As a result, I again have LED # 2 flashing. I also...

Yes, I agree, but cpus generally doesn't go bad without a reason and that's why I'm concerned. Am I forgetting to check something else?

Thanks for the tip! In fact, I ordered a PC motherboard to test this processor and I will probably have it on hand tomorrow or the day after tomorrow. I will also have another CPU in the next few days. I tested the logic board with the resistor R6903 in place (as suggested and shown in the...

Not yet. Please don't get me wrong, I consider your advice to be of great value and I will replace the mosfet as suggested. I live in Brazil and even parts like these have to be imported from other countries or removed from donor boards. I did both, bought a donor board and ordered the...

Removed CPU and checked that the low resistance (0.4 ohm) on PPVCORE_S0_CPU and PPVAXG_S0 came from it. As designed, the board will not go past S5 state without the CPU. What do you suggest to do from here?

I tested all the rails and some are really low-resistance. I would be grateful if someone could indicate to me if these resistances are within what is considered normal: PP1V05_S0_CPU - 5 ohms PP1V05_S0 - 28 ohms PPVCORE_S0_CPU - 0.4 ohms (i7 CPU) PPVAXG_S0 - 0.5 ohms PPVCCSA_S0 - 3.2 ohms...

Thanks for the clarification. What I would like to understand, to proceed with the diagnosis, is why the board is cycling all lines on and off. Is it a transition (S5 to S0) commanded by the PCH due to a previous power failure?

I am waiting for a donor card and I will change Q7950 as soon as it arrives. In the meantime, if possible, I would like to understand the board's powerup process. I watched several videos of Louis on the macbooks, but found nothing on the iMacs. I already fixed a macbook with a problem in one...