On Mon, 22 Jun 2020 16:30:01 +0000, Doug wrote:

>Yes its true, but before you let a disk spin backwards, you checked the 
>fans in the logic gate, they were 3 ph too. Depending on how they spun 
>(clockwise or counterclockwise), you had the phases corrected. I never 
>spun up a drive that went backward using that technique.
>And if it was say a 2365, or a 2860 or 70, it would power up just fine, 
>then get a thermal since the fans were spinning in the wrong direction.
> 
There are circuit diagrams of various phase testers on the WWW, But
I'd think the ideal is a vane on a microswitch.  That verifies:
o Correct phasing.
o Fan operation.
o Unimpeded intake duct.

-- gil

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