Apple MacBook A1211 (820-2054-B) - no chime

[boofoo]

Observations

Green light of power adapter illuminates when connected to computer port.

When power button is pressed:

1) Both fans initially run on slow speed
2) White light on screen latch turns on
3) CD/DVD drive does not activate
4) Chime is not heard
5) Display does not illuminate

I first thought that the U0700 CPU might not be getting power. U0700 requires three sources of voltage - CPU CORE POWER (PPVCORE_S0_CPU), CPU IO POWER 1.05V (PP1V05_S0_CPU), and CPU INTERNAL PLL POWER 1.5V (PP1V5_S0_CPU).

On the top side of the logic board, I detect ~1V at PPVCORE_S0_CPU and correct voltages at PP1V05_S0_CPU and PP1V5_S0_CPU. I have not yet flipped the board to verify that these voltages reach U0700. However, after powering the computer on with the power button, the fans eventually run at full speed speed presumably due to CPU heating.

I'm hoping that members here can suggest some logical troubleshooting to help me diagnose this problem.

I have the 820-2054-B schematic and boardview, if additional information would be helpful.

[boofoo]

Re: Apple MacBook A1211 (820-2054-B) - no chime

The diagram below shows the three power inputs for the CPU.

Also attached are the 820-2054-B schematic and boardview.

[boofoo]

Re: Apple MacBook A1211 (820-2054-B) - no chime

More information...

As soon as I connect the power supply, the fans run without the need to short the power button tabs on the logic board.

Also, does the fact that, after connecting power, the fans initially run at low speed but in less than 30 seconds run at high speed suggest an issue with the CPU thermal sensor circuit?

Any thoughts?

[dellxps15]

Re: Apple MacBook A1211 (820-2054-B) - no chime

already tried a pram reset and smc reset ?

[boofoo]

Re: Apple MacBook A1211 (820-2054-B) - no chime

already tried a pram reset and smc reset ?

Yes. Sorry. I forgot to mention.

SMC reset - no joy.

PRAM reset - The computer failed to respond to this command consistent with its failure to boot.

Looking for a connection between symptoms of high fan speed and the computer starting itself without a power button signal, I see that both functions are processed by the U5800 SMC chip (see attachments).

Thoughts? Diagnostic tests?

[boofoo]

Re: Apple MacBook A1211 (820-2054-B) - no chime

I re-measured the three sources of voltage for the U0700 CPU:

1) PPVCORE_S0_CPU should read 1.1V. At R6220 and R7507 in this circuit, I read 0.93V. **Is this reading too low and potentially the cause of the problem?**

2) PP1V05_S0_CPU should read 1.05V. At R0720 and R0721 in this circuit, I read 1.042V.

3) PP1V5_S0_CPU should read 1.5V. At C0980 and C0981 in this circuit, I read 1.49V.

[alihomee]

Re: Apple MacBook A1211 (820-2054-B) - no chime

this model always have graphic chip issue just make a reflow to confurm

[boofoo]

Re: Apple MacBook A1211 (820-2054-B) - no chime

this model always have graphic chip issue just make a reflow to confurm

Do you know which graphic chip? Would a problem with said chip, if bad, cause all of these issues:

*Computer immediately powers up and fans run without shorting power button pads on logic board.

*On power up, chime is not heard, and CD/DVD drive does not activate, though white light on screen latch turns on.

*Both fans initially run on slow speed, but ramp to full speed in about 30 seconds.

*Display does not illuminate.

[alihomee]

Re: Apple MacBook A1211 (820-2054-B) - no chime

its normally ati or nvidia

[boofoo]

Re: Apple MacBook A1211 (820-2054-B) - no chime

its normally ati or nvidia

One of these chips (see attached)?

[boofoo]

Re: Apple MacBook A1211 (820-2054-B) - no chime

its normally ati...

Thanks. Based on your tip, I made some voltage measurements on the PPVCORE_S0_GPU that supplies 1.1 volts to U8400 ATI M56P GPU. I immediately found two problems:

1) R8630 (0 Ohm) = 1k Ohms, 1.047; In addition, both pins are grounded. This resistor connects to VDDCI pins of U8400 ATI M56P GPU.

2) L9140: Both pins are grounded, and the component looks blown. This inductor connects to MPVDD pin of U8400 ATI M56P GPU.

Looks like I'm chasing a short to ground in the VCORE GPU circuit.

Thoughts? Suggestions?

[boofoo]

Re: Apple MacBook A1211 (820-2054-B) - no chime

R8630 is definitely blown, but bypassing the resistor with a jumper wire had no effect on the problem.

L9140 turns out to be fine.

So...the problem still remains a mystery.

Where should I look next?

[DopplerDuck]

Re: Apple MacBook A1211 (820-2054-B) - no chime

I have the exact same issue on an A1398 820-3609-A. Did you figure out where the problem was?

[piernov]

Re: Apple MacBook A1211 (820-2054-B) - no chime

A1211 and A1398 have absolutely nothing in common. Open you own topic, describe your own board history, problem and symptoms. Additionally, 820-3609 is not the main logic board model number.

[lcdcaps1]

Re: Apple MacBook A1211 (820-2054-B) - no chime

hi what was the outcome of this please

[weswe]

Re: Apple MacBook A1211 (820-2054-B) - no chime

didnt work in boardviewer.
can you reupload?