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Mystery wiring on a small DC motor

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Michael Gilligan21/11/2019 18:23:35
15715 forum posts
687 photos

I have just scrapped a TEAC MC-DX10 'MICRO Hi-Fi SYSTEM' and salvaged a few useful parts.

One of these (7) is a small 'motor bracket assy' which operates the sliding door.



So far, so good... But:

The motor is a Mabuchi FF-130SH **LINK**

and a single wire goes to one terminal ... and then links to the other [shorting them together]

Can someone please suggest what this is supposed to achieve ?

[ sorry, no I did not take notes or photos of it in-situ ]


Ed Duffner21/11/2019 18:39:24
799 forum posts
91 photos

Hi Michael,

The motor itself appears to be just a simple dc motor used in toys etc, from online spec's.

Could the link wire actually be a sleeved, tiny coil, noise supressor and the 'other' connector is perhaps normally connected to, or in contact with a metal chassis of the player?


jason udall21/11/2019 18:58:59
2024 forum posts
41 photos


My suggestion would be a damping function.

By shorting a small DC permanent magnet motor

The tendency to self limit the movement speed.

Basically using "back emf breaking"

Unless as suggested the single wire has two conductors then no current could flow to power the motor.

Michael Gilligan21/11/2019 19:31:54
15715 forum posts
687 photos

Update: I have just checked the PCB "Servo Board' which was destined for the 'recycling site' ... it clearly has positive and negative connections; so I can only assume that one wire broke off at the solder joint during removal.

I'm sure Jason's analysis must be correct ... and am grateful to you both.



Edit: for the avoidance of doubt ... the shorting link is just that: a length of the connecting wire.

Edited By Michael Gilligan on 21/11/2019 19:34:45

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