Re: Apple 400k drive

maybe you can get them from a newer 800k or 1.4 drive or even a pc drive. furthermore some motors in laserprinters use the same technique.

On 9 mrt 2011, at 00:07, Terry Stewart wrote:

> Hi Helmut,
>
> I'm not sure of the exact part description of the passive hall sensor.
>
> In the first instance, I'm going to try and identify which ones are faulty, and mix and match so that out of two non-working drives I get at least one that behaves as it should.
>
> Terry
>
> ----- Original Message ----- From: "Diogenes45" <helmut_post_at_email.domain.hidden>
> To: "LisaList" <lisalist_at_email.domain.hidden>
> Sent: Tuesday, March 08, 2011 9:48 PM
> Subject: Re: Apple 400k drive
>
>
> Hello Patrick,
> and greetings from Helmut Post!
> Do you remember me?
> My third IDE File is running very well!
> Back to the topic: What is the exact part description of the passive
> hall sensor?
> Perhaps I know a place where to get obsolete and very hard to find
> parts.
> Lately I purchased 2 Z8 processors (Zilog 8631) with 4 KB XROM for
> the 10 MB Profile - these are very hard to get, but there are still at
> least more than 40000 pieces left today. The price was $ 4.06 for
> each part.
>
> Helmut
>
> On 8 Mrz., 08:24, PSchaefer <dr.p.schae..._at_email.domain.hidden> wrote:

>> On 7 Mrz., 21:18, "Terry Stewart" <te..._at_email.domain.hidden> wrote:
>> 
>> > I've been in discussion with folk on the classic computer mailing list > about
>> > this. The feeling was it could have either been the TA7259 motor > controller
>> > IC, the associated caps or on of the hall-effect devices in the motor
>> > controller IC itself.
>> 
>> Usually this is attributed to the hall effect sensors which get a
>> voltage offset.
>> 
>> With a good sensor, you can measure half the supply voltage at the
>> outputs when no magnetic field is applied. The difference between both
>> output terminals goes positive or negative, depending on the field
>> direction.
>> 
>> With a bad part, this signal is shifted towards the positve or
>> negative direction. Therefore its zero crossing is not at the point
>> where the controller expects it, which makes the signal unreadable.
>> 
>> A drive with one faulty sensor will spin when started manually,
>> otherwise it will do nothing or oscillate. With two broken sensor, the
>> motor cannot operate at all.
>> 
>> Up to now I did not find suitable replacements for the passive hall
>> sensors used in the 400k drives.
>> 
>> Patrick

 --
Groeten,

Simon
simski_at_email.domain.hidden

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