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

So an update on this: After fiddling and fiddling the drive simply wouldn't come up. I'm less convinced this was a prototype drive and is simply a very low serial number.

Using BLU I was able to low level format the disk, test it, then write a copy of my working Widget to it. Hats off to James for writing such a great utility!

Now that I have another widget to play with I think I'll load Xenix :)

-J

On Sat, Jan 3, 2015 at 4:13 PM, Jason Perkins <perkins.jason_at_email.domain.hidden> wrote:

> 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
>

-- 
Jason Perkins
313 355 0085

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