Lionel AMC Question (solved)

Hope I get the lingo right- Accessory Motor Controller.

-Does the TMCC signal go thru this controller or is it just straight DC?{the AMC is just a relay of sorts- right?}

-Is that motor known to be good?...got another motor to try?

- If that's a mabuchi they can "usually" take alot of voltage- some up to 30v from what I've seen on their website{but not all motors!}

- how high was the throttle turned up?...3/4, 1/2, 7/8...

-As I recall, don't you have a clamp on amp meter?- give it a test read though I can't see that motor pulling 2 amps just spinning freely.{unless it were bad/worn}

-lastly, is this AMC new and/or work well for other accessories to prove itself?

   ...Even if it is brand new, you know these things can go bad...nobody else chimed in yet so I thought I'd toss a few ideas at ya... 

Bob,

The TMCC signal just goes to the controller to command the operation, the motor outputs are just either AC or DC.  The AMC is actually an electronic power control, as you can vary the speed of the motors in the configuration.

My motor is good, and another does the same thing.  The motors also run just fine on a DC power supply with no hesitation to as fast as I feel like pushing them.

Clamp-on meters are only for AC, but I'm thinking of checking the current with a DC meter.  The thing is, running the motor at any speed I desire on the DC bench supply, it only pulls at most a few hundred milliamps.  The AMC has been around, but it was unused.  Since both channels act the same, and all the other stuff work as intended, I'm 95% sure it's not broken.

I guess these things are not in as common use as I might have imagined.

I have two AMCs wired up, one to a log loader, one to a gantry crane.  If the fixed voltage is set too high on either motor in the crane, the motors will stutter and spark.  I always assumed too much power to the motors was fouling up their operation.  Once I set the voltage to the optimum setting, just under the point where the motors will get rough, it works great. 

electric novice helping the electrical expert-LOL

I just looked at the AMC manual p.6 and it was suggested that a 4.7uF 50v bi-polar cap be used for irregular operation.

Would that make a difference from the one that you used?

I'll try a larger cap, can't hurt.  I totally missed that suggestion, I need to read more carefully.  I'll dig out a larger capacitor.

Tried capacitors up to 10uF NP, no change.  The amperage to the motor was well under an amp when it started stuttering, so I'm not sure what the issue is.  I was feeding it with a 1033 transformer at 16 volts.

If you are supplying more voltage than the motor is intended for, could it a problem with back-EMF upsetting the AMC?

I was suspecting some feedback from the motor, but it's hard to believe that 8-9 volts is too much for a truck motor.  It doesn't appear to be noise, and the circuit shouldn't care about back-EMF if it's not looking for it.  Even if I put a load on the motor, it still has the issue.

I'm hoping that when I test on the turntable tonight that I don't need the power and I can just ignore this.

John, try dialing down the AMC supply voltage...I'd say start at 10v and see how the motor runs, then try 11v...you know...till it stutters again, then back off to the smoothest running supply voltage. When activated is the AMC delivered voltage set or is it variable from the remote?

Oh, dumb question -is there 1 supply input to the AMC or is it capable of taking individual supply voltage per each add on accessory? I'd hate to see a low single supply voltage being dropped so low it adversely affects other items on there.

Hi John,

Intrigued by this problem, I've just read the AMC's manual, and I see that it specifies 12V AC as the recommended input voltage. As Bob suggests, try lowering the input voltage to see if it helps.  Good luck.

John,

It appears there are commands for either AC or DC output. Could that be issue?

I'm currently running it at 12V from a 1033, and I'm using the DC commands.  If I tried to run that motor on AC, it would be ugly.

In any case, I connected it to the target device, a turntable with a Pittman motor, and we didn't have any issues at any speed.  So, it must be a characteristic of the two different truck motors in my parts box, even though they're perfectly working motors.  One is a Lionel, the other an MTH.

Since the target environment doesn't have a problem, I'll consider this one solved, even though I don't fully understand why it happens.

Well that's good to hear...but do toss us a thread on this turntable build of yours...we could "around" with that for a while.{...sorry, somebody had to say that...}

50,000 comedians out of work, and you're trying to break into the field.

John,

The AMC uses Triacs on the outputs and as such can misfire on the outputs under certain types of loads.  There are various versions of the AMC (used in the Lionel TMCC controlled Log loader ect); that address the issue.  The stock AMC does not have the adjustments.

The reason I hopped on this thread was mention I am working on an AMC2 with FET driver outputs to solve this issue.  Conceptually, I was thinking to support 2 motors, and 2 lights instead of 4 motors.   The 2 motor channels would be bi-directional and operate with optional BACK-EMF so the motor could crawl.  I think 2 motor channels are sufficient, but appreciate your input as we work through the design.

Jon, the AMC I have supports two motors and two lights, at least that's what the documentation says.  It does appear that the lighting channels behave identical to the motor channels, are you saying they're really the same thing, just documented as lighting channels?  We have the 6-14183 AMC.

I'm guessing for some reason my truck motors were confusing the AMC?  I tried running them with no load and under a load, and always got the stuttering when they were running faster.  For some reason, the Pittman motor on the turntable seems to run fine no matter what speed I use.

I love the idea of speed control on the motor, that would really make doing stuff like a turntable easy and precise!   I'm assuming this would be similar to what is done on the Cruise Commander?

What would be different about the two lighting channels?  Would they be just simple on/off channels, or would they have variable voltage and AC/DC capability like they do now?

The 4 output channels are identical on the AMC PCB, my memory slipped up in that the documentation shows 2 lights & 2 motors.  The 4 channels are TRIAC driven with variable output, and as such the AMC features a selection of select AC or (quasi)DC drive.  If speed control is to be realistic to implement, the motors would have to be DC only and designed to work just like the Cruise Commander.

I could have on/off operation (or variable) for the lights, perhaps adding another 2 outputs for a total of 4 light controls.  I can make room on the output screw terminals by using a slightly smaller terminal block. 

I am still formulating the design, so any feedback based on your experience with the current AMC is very appreciated.

Hmmm, not really, see, I messed up the line- it was supposed to be "we could go around with that one for a while"...it could be a back up job......maybe I should just stick to model trains.

I wondered what you were talking about Bob.

A suggestion.  If the lighting outputs could be triac controlled like the old ones, you'd still have the option of AC or DC motors, as well as the speed controlled pair of DC motors.  This would make it a pretty flexible box, up to four motors, two with speed control, and two with either AC or DC capability.  And, the option of using the two for lights.  Extra lighting outputs would certainly not be a bad thing as well.

I think I'd buy a couple of those!

I was going to say, like a real pro, he goofed up the punchline.  Maybe try smashing watermelons?

John, have you goofed around with an ARC?  They are a lot of fun.

I have not tinkered with the ARC.  With Legacy, I have that capability, though it might not be as extensive as the ARC, I haven't done much with it yet.