i have a monogram porsche 904, bone stock except for urethane tires. i run it with no magnets.
the problem is that if you place the car on the track and pull the trigger, the car will not go. however, if you give it a slight push start, it will run. by "slight push start" i mean VERY slight. you can even blow air on the back of the car and it will start moving. the same thing happens with the rear tires held off the track - the tires will not move until you help them along slightly with your finger.
the strangest part is that the car runs totally fine once it is in motion. but if you come to a complete stop, it needs another push start.
is this motor dead? is there anything i can do to make it work again? i already replaced it with a scaley F1 motor, but it is too fast for my liking. i'd prefer to get the monogram motor running again.
Guin: i'm positive it is the motor. i tried fiddling with the braids, lead wires, etc. nothing fixed the problem. when i replaced the motor, i used the old lead wires, guide, braid and pinion, and the problem was fixed immediately.
one thing i forgot to point out is that this motor has maybe 30 minutes of run time on it and worked just fine during those first 30 minutes.
i suspect the motor is bad, but it seems odd that it runs just fine after given a push start...
Does it display the same issues when you supply more voltage?
Meaning if you currently have your track at 10V and you crank it up to 15V, do you still have to push start it? If so...bad motor, and like Joe stated, a brush is wonky.
Sounds like a broken wire on the armature causing you to have an open pole. It is odd that the speed has stayed the same as usually when this happens, the car is slower. I have had this happen with an MRRC car and when I contacted the shop where I bought it about a new motor, they sent the whole car as a replacement!
You lose very little top end when one pole goes open. The torque however goes to shite. Hence the little push that is needed. Do you own a multimeter? Place it across the braid and rotate the rear wheels. You will get fluctuating readings of 4-10 ohms depending on the motor, but at some stage the reading should go open circuit. That will confirm the open pole.
You lose very little top end when one pole goes open. The torque however goes to shite. Hence the little push that is needed. Do you own a multimeter? Place it across the braid and rotate the rear wheels. You will get fluctuating readings of 4-10 ohms depending on the motor, but at some stage the reading should go open circuit. That will confirm the open pole.
cheers
rick1776
Sure does sound like an open pole.
There are a couple ways to get that condition. A broken wire, like Scott suggests, or a bad/misaligned motor brush. The commutator is in 3 segments, and the brushes have to be in contact with two of those segments at all times. When the brushes are fine, no problem, but if they get misaligned, there can be a point during armature rotation where the second brush almost makes contact with a second segment. No contact, no current, and the motor is stopped. Pushing the car a fraction makes the commutator rotate just enough to make contact again, and *pow*, you've got power back. The momentum of the armature is enough that during running, it just skips over that dead point and gets power again almost instantly. Sort of like you're not firing on all cylinders.
interesting. i have a small wattage soldering iron that i've never used. might be time to fire it up! i'll open the motor this weekend and see what i can figure out.
Mike -- I'm in the 'commutator' camp --- the brushes might be worn back enough not to make contact until the arm actually moves --from slight physical force--!!
odd motor problem
Linear Mode
