Hi,

I would like to have your opinion about this circuit with a burnt small 6-pins component which is coming from the WD Caviar SE16 series (Model WD500AAKS) of an iMac:


The yellow rectangle shows the burnt component, at location Q3.
The red ellipse shows more or less the damaged area with melted material.
The cyan ellpise shows the melted foam.

Firstly, I would like to know if this overheating is related to some specific component inside the drive. I read that the WD500AAJS are known for failing preamplificators.
(Source: http://forum.hddguru.com/viewtopic.php?t=9290)
Are the WD500AAKS too ?

Assuming that the component burned because of an internal problem, knowing which component is likely to fail would help to find a drive with not necessarily the exact same DCM but compatible for the wanted part(s).

Secondly, concerning the circuit, replacing the burnt component appears hazardous, since the circuit is multi-layers and also because near Q3, at location C36 is another burnt component which is very small. The overheating seem having been strong.

So, I'm planning to use a new compatible circuit.
There is no U12 ROM for this model and the firmware is stored in the large Marwell chip, and in the service area.

Is it easier to unsolder/resolder the Marwell chips on a rework station or flashing the firmware? I assume that the second method is the way to go because of the many pins of the Marwell chip.

Then, which software would you recommand to read/write the firmware ?

I assume that WDR-Demo, based on SATA would not work because the drive is not spinning at all. Or I'm wrong?

I read about a software named Ucontrol or something like this, which seems in Chinese and sending TTL commands and using the Tx/Rx pins, but I cannot find the post with the download link anymore. Would you recommand it or something else (possibly cheaper than the PC3000...)?

I can't tell exactly from the blurry picture but I believe that's some sort of power regulating chip. I had one just this week with a burned one in almost the exact same location, and replacing the PCB was all that was required to recover the data.

Moving over the ICU is going to be tricky. I know some guys have done it, but it certainly isn't the recommended way. Usually for models with no U12 the ROM can be rebuilt from the service area. Do you have access to any pro data recovery tools like PC-3000, DFL, or MRT?

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it's a 6 pin transistor

regarding the MCU, it depends on your soldering skills.
personally i wouldn't bother doing it, using a compatible enough ROM ver. to get acces to SA to rebuild the ROM it's a lot more faster, i think (IMHO).

Qn is the standard circuit reference for a transistor. In this case it appears to be the chopper in the Vcore regulator. In the absence of professional ROM rebuilding tools, a competent tech would be able to reconstruct the Vcore supply, even if this required an external regulator. The parts cost should be less than US$10.

That said, I would first measure the load resistance. If it is close to zero, then the MCU is probably dead.

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A backup a day keeps DR away.