"Ross Herbert" wrote in message
...
On Mon, 24 Jan 2005 02:00:31 GMT, "Martik" wrote:


"Bill Jeffrey" wrote in message
news:m3CId.43060$St.19486@fed1read03...
I would bet that the extra pair of wires bring variable power to the
stator, providing a variable magnetic field and thus varying the speed.
With no power on these leads (no power on the stator), there is no field,
so the motor won't turn, of course.

Since you just got a new speed control unit from Dremnel, you have to
assume that the speed control unit is OK. This leads you to suspect
that
the problem is in the wiring inside the motor, or the cord from the
speed
control unit to the motor (assuming you didn't get a new one with the
new
speed control). So start at the speed control - does it put power on
the
yellow and white wires, as well as on the red and blue wires? If so,
does
the power make it through the cord to the pcb mentioned in another post?
If so, does it make it to the motor?

Find out where you are losing power in the yellow / white wire circuit.

http://www3.telus.net/martik/

Referring to the above pics:

Motor1 is the PSB, the small white connector (upper right) with
grn,brn,blu
goes to the speed control. There is continuity to all 3 wires and voltage
(2-3 v) and resistance (4-7k) vary when adjusting the control. The large
white connector goes to the motor with 100v between the blu and red; 50v
between blu and yel; 50 v between blu and wht, ov between wht and yel with
NO change when adjusting the control for both 100 and 50v readings

Motor2 shows the pcb in the motor. I get 100v between blu and red and 50v
between blu and wht, 50v between blu and yel with no change when adjusting
the speed control. I cannot see any connection under the pcb between the
red/blu and wht/yel wires.

So, I conclude that all the wiring for those 2 connectors is ok but don't
understand why there is no change when adjusting the speed control.

Motor3 show closeup of wiring from pcb to 'end cap'

Motor4 shows other side of end cap with magnetic disc

Motor5 shows commutator inserted

Motor6 shows housing and armature. Those odd shaped thinks in the housing
are just washers.

Thanks again for your help!


A great set of phoros...

Amazing what a macro setting and high F-stop(8), no flash and a self-timer
can do


The motor is definitely a permanent magnet motor, so no field
winding...

Since you know the controller is ok the problem can only be in either
the armature or whatever is hooked up to the yellow and white wires on
the brushes pcb in the end cap. Since the armature is new it is
unlikely that there is an internal short in the winding, but this is
still a possibility. My guess is that whatever is connected to the
yellow and white wires provides some sort of feedback to the
controller and if this device is not working then the controller
doesn't know what to do.

Could you suggest a way to just bypass the controller and run at full power?