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?...
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Re: Apple MacBook A1211 (820-2054-B) - no chime
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....
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Re: Apple MacBook A1211 (820-2054-B) - no chime
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....
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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.
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Re: Apple MacBook A1211 (820-2054-B) - no chime
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?...Last edited by boofoo; 07-22-2016, 10:07 AM.
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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?Last edited by boofoo; 07-21-2016, 09:12 PM.
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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....Last edited by boofoo; 07-21-2016, 12:21 PM.
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Apple MacBook A1211 (820-2054-B) - no chime
[B]Observations[/B]
Green light of power adapter illuminates when connected to computer port.
When power button is pressed:[INDENT]1) Both fans initially run on slow speed
2) White light on screen latch turns on
3) CD/DVD drive does [B]not[/B] activate
4) Chime is [B]not[/B] heard
5) Display does [B]not[/B] illuminate[/INDENT]
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)....Last edited by boofoo; 07-21-2016, 10:49 AM.
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Re: need board view for Apple A1278
I now have the .BV file for the 820-2054 logic board. I would like to share it. Can somebody please tell me how to upload a zipped file.
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Re: need board view for Apple A1278
Edit: Sorry, my Apple logic board number should have been more precise.
MacBook Pro 15” 2.33GHz Core 2 Duo late-2006 (T7600) A1211 (EMC 2120) = 820-2054-B
If possible, I'd also like to obtain BoardView files for the logic boards of my other two laptops:
MacBook Pro 15” 2.66GHz Core 2 Duo mid-2009 (P8800) A1286 (EMC 2325) = 820-2523-B
MacBook 13” White 2.0GHz Core Duo mid-2006 (T2500) A1181 (EMC 2092) = 820-1889-A...
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Re: need board view for Apple A1278
Might someone kindly post a link for the Apple 820-2054 board view. Thanks.
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