Re: Just got a possible prototype Widget disk - any special considerations?

I had some more time to fiddle with this today.

Patrick, I think I was not clear in my last message, the initial squeak-squeak seeking operation isn't repeated over and over, a smaller seek operation is.

I reduced the gain adjustment after taking a photo of the pots. The drive didn't come up normally, but it did get far enough for BLU to collect some information:

https://lh3.googleusercontent.com/-zrKPwqYA3eQ/VKhYiAt-CPI/AAAAAAAAF30/OF36077TFuA/s640/IMG_20150103_155048.jpg

However I'm unable to get it to read any data off, it simply tries over and over until BLU times out.

I have a 2nd probe on order for my scope.

I did try the servo & R/W boards from my working widget, and the drive seemed to work even less.

Thanks for your input!

-J

On Wed, Dec 31, 2014 at 11:52 AM, PSchaefer <dr.p.schaefer_at_email.domain.hidden> wrote:

> Am Dienstag, 30. Dezember 2014 20:21:29 UTC+1 schrieb compu_85:
>
> >https://lh5.googleusercontent.com/-V4qbUsfa-UA/VKH8-Z9ysEI/
> AAAAAAAAF0o/ly3O9bKFnBY/s800/IMG_20141229_200128.jpg
>
> At least your servo board is one of the oldest made. The first PCB layout,
> and revision -A. I don't know if this is a prototype or if these also have
> been shipped to customers. All my Wigets look like they got a lot of manual
> tweaking after manufacturing, so it seems to me that Apple shipped only
> "prototypes" before they cancelled this product line.
>
> > Upon powering it up it spins fine, unlocks the head brake, does the
> initial
> > squeak squeak then seems to get stuck doing the same operation over and
> > over. From your notes this would be the r-w test on the spares track.
>
> It seems to me that the initial squeak-squeak (data recal) is repeated
> over and over, so I would check the servo board first.
>
> If you have access to an oscilloscope: connect it to TP9 and TP8 on the
> servo board and set to X-Y mode. An old analog scope does this better than
> the modern digitizers. During the recal attempts you should see a circle
> with a diameter of approximately 5 volt. If it looks more like an egg or is
> significantly too small, your mainboard is misaligned or there is a fault
> in the HDA or mainboard. If the circle looks good, replace your servo
> board.
>
> If the lissajous circle looks good and recal fails even with a known-good
> servo board, you can try to reduce the servo gain. This is the lowest one
> of the triple pot on the edge of the motherboard. Mark the old position
> (take a photo) and change the setting carefully. With too much gain, the
> heads will bang into their endstops, with too little gain the seek will
> timeout before settle. Apple recommends 35ms for 60 tracks, but with rotten
> mechanics a slower value (like 40ms) works better.
>
>
> I do not know if BLU allows you to read the fault memory of the controller
> board. This will give you additional information which step of the selftest
> failed.
>
> Formatting will not be possible until all tests pass. But you want to get
> the data from the disks, don't you? So I would try everything else first.
>
>
> Regards
> Patrick
>
>
>
>
>
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-- 
Jason Perkins
313 355 0085

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