Epson PX-8 specifically TF-10 problem...

[allison]

On 12/09/2017 09:14 PM, Brent Hilpert via cctalk wrote:
> On 2017-Dec-09, at 6:06 PM, allison via cctalk wrote:
>> On 12/09/2017 07:52 PM, Fred Cisin via cctalk wrote:
>>> On Sat, 9 Dec 2017, allison via cctalk wrote:
>>>> I have several Epson PX-8s and i used them.. They work well with the
>>>> various wedges I have.
>>>> I also Have a PF-10 which is the portable 3.5" 40 track two side floppy.
>>>> The problem is it randomly does not turn the media unless I give it a
>>>> push to get it turning.
>>>> Things checked:
>>>> * Batteries, NEW fully charge (Both).
>>>> * internal Power supplies, current voltage and bridged with external
>>>>    supplies does not help.
>>>> * media checked for binding, it does not.
>>>>  When it turns it reads and writes correctly and at the correct speed.
>>>>  It may do so without help for many tries then will stop required a
>>>> manual push.
>>>> At first glance I though there were motor bearing issues but have
>>>> verified
>>>> this is not so.   If I force motor on and restrain it I has good torque
>>>> and no
>>>> dead spots.  All signals in the motor control look good on the scope.
>>>> Any thoughts?
>>> How does it detect the presence of a disk?   and/or disk change?
>>>
>>>
>> Functions normally save for the motor does not always turn on command
>> but will if manually pushed.  All other functions are normal.
> How about a problem with the current supply to the motor, such as low gain in the driver.
> A progressive failure may be just on the edge of supplying enough current to keep it rotating, but not enough for startup torque.

That was my thought and I checked, not the problem.  I suspect that the
magnets in the rotor
have gotten really weak.

Allison