correction - driver IC is TM2620D, no logo

"N Cook" wrote in message
...
VCR works fine in play and record as long as the head drum gets up to
speed
by flicking by finger while the tape is lacing.
So assuming nothing wrong with the bearing , normal free movement when
unpowered.
Sometimes drops out in play or record on hitting ruffled tape so a motor
problem.

VCR is Osaki VCR 34H , no knowledge, so i don't know if correct ps
voltages
for a start

3 lines from the TA2620D driver IC to the coils and further ends of each
are joined together but not returned to anywhere so presumably 3 phase.
There are 12 coils from these 3 lines mounted on the iron frame with 12
'poles'
The surrounding magnet rotor part has 8 North poles, 8 South poles.
On pcb 3 hall effect sensors presumably for relative phase monitoring
these
magnets and a separate magnet pip on the outside of
the rotor and 1 hall effect sensor for 1 pulse per rev.
But what is the PCB track/coil ? etched on the board under the rotor.
Not connected to anything else on the motor sub-board and just copper
track
as far as I can see,
roughly like Beta vcr tape path, one track runs right round circularly and
returns 'circularly' with 24 castellations pattern.
What and how is it sensing or sending anything? and what's its function ?

I have another matching salvaged multimagnet rotor so can eliminate
magnetisation loss as reason

Any tips for 1 or 2 channel scope for monitoring driver IC, does not run
hot
and
unpowered 'diode' DVM checks seem reasonable.

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