Gearslutz (
-   Geekslutz Forum (
-   -   Otari mx5050 capstan motor TACH (

parpat 30th September 2019 04:08 AM

Otari mx5050 capstan motor TACH
the capstan motor on my Otari locked up, when I opened the motor casing, a small plastic piece fell out, motor spins fine, that piece looks like it has a LED on it, there are three of them on the sensor,
two are off, trying to figure out where they need to be glued back,
anyone have pictures

parpat 11th October 2019 07:52 PM

1 Attachment(s)
here is a picture of the 'sensor' with one 'chip'

Richard Crowley 12th October 2019 04:07 AM

That looks just like a tape head (perhaps a small "mono" tape head in a cassette machine).
It likely "reads" a magnetic pattern around the flywheel (or some other very close rotating part).
And the signal from that head is what feeds the speed control of the motor.
So that the speed control circuit knows exactly how fast the capstan is rotating.

That little piece off to the right (with the green coil of wire) looks like what is inside a tape head.
A couple of protruding pole pieces and a coil of wire. That is basically what any tape head consists of.

If you had mentioned the model number of your machine (or the motor) we might have been able to offer more help.

waltzingbear 12th October 2019 05:30 AM

see Michael's web page, it describes exactly your problem.

start looking for a new motor or George at Athan can rebuild it for $300

oops, Note: Rebuild does NOT include replacement of damaged coil assembly. Additional charge applies.

you'll also get the surface of the shaft redone which is a very good thing.
a new pinch roller and a non shiny capstan surface will help your deck run with lower wow and flutter.


oh, and yes, that is a tape head that reads hte outside tach on the motor for speed control. the other piece is part of the drive assembly and needs exact alignment. It will cog without correct alignment.

parpat 13th October 2019 01:20 AM

thanks , yes I see the tape head but the black 'coil' along with 2 others (one still on that part) have fallen off where they fit exactly is the question
as far as model number all it says is MX5050 , serial number is 177,,, heard the 2nd two numbers indicate the year made ??

Think its time to dig out the Ampex's

Stereo Steve 23rd May 2020 04:20 AM

Same thing happened to me on a MX5050 B ll. The rotor and stator are beautiful. Did anyone ever experience a H M S counter that counted negative either way it was turning? (In both directions?)