Re: a bit OT:Repairing brushless DC motor?

"Tim" <duttondock@xxxxxxxxxx> wrote in message
news:47a10c33-760a-489e-a9b7-b2534ff20367@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On 23 Aug, 18:43, "Phil O. Sopher" <inva...@xxxxxxxxxxxxxxx> wrote:
1. The sensor is probably an opto, not a hall, with the black and red
being
the drive for the LED and the white being the phototransistor return.
Not sure whther that would be possible, AIUI the motor rotor runs in
water and is sealed from the windings. I may have that wrong, though.

If optical, then there'd be some form of slotted disc attached to the rotor
that
would pass between the opto components. The opto components could then well
be
sealed and isolated from the water.

Thinking again on this, if a Hall sensor, then it would incorporate its own
amplifier
ahich would account for the red/black feed wires. So, it could either be a
Hall effect
or an opto.




2. Something is wrong because the "Speed Rail" is not connected to
anything.


If the diodes are Zeners, will it no be supplied via the bottom diode
from the + rail (not a zener) and the third ?Zener from the left?

No. Something has to be there to pull the speed rail up (in a graphical
sense to the negative rail. The emitters of the c639's have to be pulled
up towards the negative rail.

There should be a resistor from the Speed rail to the -ve rail, otherwise
there is
no source of emitter current for the c639's
3. Most of the diodes are to suppress the Ldi/dt voltage spikes when the
inductors
are switched off.
4. Can you read off the part numbers of the "zener diodes"?


.

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