PhilP
G Scale, 7/8th's, Electronics
Trainli?
Circus Engine
- Thread starter zman50
- Start date
I checked. Did not have the two gear one. Thanks
Greg Elmassian
Guest
your meter most likely needs a battery for ohms measurement...
if you are sure that the switch is in the right position, and the probes in the right sockets, that is the most likely problem.
When was the last time you replaced the battery?
also you could provide the model number and we could look it up.
Greg
if you are sure that the switch is in the right position, and the probes in the right sockets, that is the most likely problem.
When was the last time you replaced the battery?
also you could provide the model number and we could look it up.
Greg
I tried a different meter that seems to work, the numbers of ohms were all over the place bouncing around from ~35-~180. Never really settling down.
Greg Elmassian
Guest
are you using alligator clips to the brushes or are you just holding the probes with your hands?
I will try the clips. Thanks
Greg Elmassian
Guest
you have to use clips, when measuring low ohms, just the amount of pressure will make a difference... then turn the shaft a bit, and don't touch it to get your reading.
Your motors will be something like 25 to 75 ohms typically, but can vary all over the place. What we are looking for is a wide variation in reading given different shaft rotational angles.
Greg
Your motors will be something like 25 to 75 ohms typically, but can vary all over the place. What we are looking for is a wide variation in reading given different shaft rotational angles.
Greg
So I put the clips on and the readings where right around 3.5 as I turned it, while set at 200 ohms. Does it make a difference where red and black are connected to motor tabs. Thanks
Greg Elmassian
Guest
no difference in polarity, you are measuring resistance of a loop of wire.
3.5 ohms sounds pretty low... I would expect 13 to 25 ohms
At 20 volts, then it would draw about 5.71 ohms if it was not a motor. Motors do not follow Ohms law.
Can you do the same measurement on a "good motor" (i realize it might require disassembly)
so the 3.5 ohm reading is pretty consistent at various different rotational positions of the motor?
That would surely explain this motor drawing 3 times what your others are.... that's too low for even a 6 volt motor...
Greg
3.5 ohms sounds pretty low... I would expect 13 to 25 ohms
At 20 volts, then it would draw about 5.71 ohms if it was not a motor. Motors do not follow Ohms law.
Can you do the same measurement on a "good motor" (i realize it might require disassembly)
so the 3.5 ohm reading is pretty consistent at various different rotational positions of the motor?
That would surely explain this motor drawing 3 times what your others are.... that's too low for even a 6 volt motor...
Greg
Yes as I turned the motor a little bit and stopped the reading remained about the same at each stop. No I will not be taking another motor out of a engine for testing. Maybe though someone else out there has a good motor that they could test or maybe already know the answer. Hopefully others may offer some input. Thanks
Greg Elmassian
Guest
Pretty darn sure motor is kaput.
Greg
Greg