Hey All,

First time looking at a Hitachi 4TB HDS724040ALE640.

It does not spin up, but get a drive ready after a few seconds. Have a donor board, done the necessary chip swap. No change. The new board still spins up the donor drive, so board seems OK.

Noticed that the drive will spin up with the HSA isolated. Any suggestions would be great?

Thanks
Joel

Bad preamp?

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A backup a day keeps DR away.

yes

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I can help with voltage measurements. That will at least confirm or discount a short. That said, if one of the voltages were shorted, wouldn't the MCU be held in the reset state, and wouldn't this mean that the drive wouldn't come ready?

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A backup a day keeps DR away.

+1

I have compiled a tutorial that should help you identify the voltage test points on most HDD PCBs. Hitachi's generally use Cuk converters. The negative preamp voltage should be accessible at one of the inductors. If you measure the resistance between that point and ground, that should tell you whether the preamp is shorted.

Tutorial - Linear and Switchmode Regulators used in HDDs:
http://malthus.zapto.org/viewtopic.php?f=59&t=231

_________________
A backup a day keeps DR away.