On Sat, 20 Oct 2012 06:19:43 -0500, "Mark Zacharias"
wrote:

"Splork" wrote in message
.. .
On Thu, 18 Oct 2012 04:44:32 -0500, "Mark Zacharias"
wrote:

"Splork" wrote in message
news Reel motor drive turning off on it's own. Lack of tape take up motion
then
shuts down Pinch Roll. Would like to scope it out for cause.

Need Teac W880RX Schematic or Service Manual. Could only find one that
costs as
much as the unit is worth. Any one able to help?? Usenet reply

Thanks



"Reel motor drive turning off on it's own"

The F/R motor is stopping on it's own, then the unit auto-stops?

It so I would suspect the reel motor itself is going open-circuit at
times.
Actually happens a lot, especially if the machine has spent much of it's
life not being used much.

In these cases, I disconnect the reel motor from the circuit and run it
with
a separate power supply for at least a couple hours in each direction.

This way you do not run the risk of damage from dis-assembly etc and
believe
it or not, never seen a re-do from this method.

I've used this method with great success in a Nakamichi MR-1 for example.

Mark Z.

Thanks Mark

Good trick.

I had a scope on the motor and the drive voltage drops in concert with the
motor
stopping. Pinch roller drops later a second or 2 later as one would
expect.

If an open motor, should not the drive power remain applied with the
cessation
of motion??

Machine has indeed had little use.



If the motor voltage drops, the motor could be shorting internally. Also not
uncommon. The cure is different - one has to find a way to clear the short.
You can open the circuit to the motor, insert a current meter. If the
current goes UP just at the instant the motor stops but before the auto-stop
triggers, the short is confirmed.

Also, the motor is running much slower in PLAY mode than in FF or REW. Does
the motor quit in FF or REW? Even if there is a short on 1/2 of the motor
rotation, at a higher speed it skips past the short too quickly to make the
mech stop. The average current is higher of course.

Of course there could be some bad connection or other causing the motor
drive voltage to drop out...

Mark Z.

Good suggestion.

Fast operations are unaffected.

The issue is intermittent. Have played for 15 min without a stop and also
almost instant start to stop.

It is a dual transport machine and both transports exhibit the same problem.

I will play with it again in the next week or 2 and see if I can observe another
facet of behavior before taking any action. A schematic would be best as I
could probe the input to the drive circuit and see if it is deterministic.

Thanks!