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Lazy Momentum

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  • Member since
    April 2003
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Lazy Momentum
Posted by Anonymous on Tuesday, March 11, 2008 12:52 AM

Hi,

   This is my first post. I just dug out my 25 year old box of model railroad stuff. Great intentions but a project never started.. $125.00 1983 dollars worth of brass Atlas HO rail. I wish I'd known about nickel rail. Maybe it didn't exist then. I don't remember.

   I hooked up my barely used 25 year old MRC Control Master I. It works fine except the momentum circuit is VERY slow to respond. It takes a long time to start moving and when it stops the power is never completely cut off to the track. The motor in my Athearn diesel/electric continues to buzz (great for the brushes and commutator I'm sure), and the headlight continues to flicker dimmly. I'm a fairly good tinkerer-just enought to be dangerous so I played with the pots inside which helped slightly with the buzzing shutdown but there is something else wrong. Bad capacitors, etc.? I know it worked much better than this when new. I'm going to waste way too much time on this no matter what. Can someone please help this stubborn buffoon... I'm not gonna throw it away. Did I mention I own a Radio Shack?

Any helpful advice will be appreciated. I can get any part that's in this thing. I'd just like to get it right the third or fourth time, and maybe save some time/money!

Thanks, Todd

  • Member since
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  • From: Pittsburgh, PA
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Posted by JoeinPA on Tuesday, March 11, 2008 12:46 PM

Todd:

It sounds to me that you may have a bad momentum capacitor.  You could try swapping it out with a new one from your store's stock.

Joe

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Posted by Anonymous on Tuesday, March 11, 2008 2:25 PM

Thanks, Joe. Would that be one of the large filter (electrolytic) capacitors? There is a 220mfd. one that I suspect is part of that circuit. The larger 470mfd. looks like it's used to filter the DC power supply.

Todd

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  • From: Sierra Vista, Arizona
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Posted by cacole on Tuesday, March 11, 2008 2:31 PM
If you are trying to run a newer Athearn diesel with a can motor, don't use that old power pack, or at least turn off the Momentum and Pulse Power switches if is has them.  The buzzing noise and headlight flicker you hear and see is because those old power packs were made to run the old Pittman open frame motors that drew a much heavier current than the newer can motors.  The can motor will be destroyed from overheating.
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Posted by Anonymous on Tuesday, March 11, 2008 2:38 PM

Cacole,

Thanks for your concern. The Athearn engine is the same vintage as the transformer, and has the classic open frame motor. I'ts also my original point of reference, since this is the same engine I used with this transformer 25 years ago. It's also been tuned up with a new set of brushes and completely re-lubed. It's not a part of the problem and performs fine with my other transformer which is identical.

Thanks, Todd

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  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
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Posted by jeffrey-wimberly on Tuesday, March 11, 2008 2:57 PM
 GNTodd wrote:

Hi,

   This is my first post. I just dug out my 25 year old box of model railroad stuff. Great intentions but a project never started.. $125.00 1983 dollars worth of brass Atlas HO rail. I wish I'd known about nickel rail. Maybe it didn't exist then. I don't remember.

  

Indeed, nickel-silver rail did exist then. I started using it in 1982.

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Posted by UpNorth on Tuesday, March 11, 2008 5:40 PM

220mfd is the usual value for momentum RC circuits. The capacitor gets charged and then releases when you turn down the throttle.  But I question the capacitor fault.  Sounds more like a diode leaking a few volts or the throttle pot itself is not cutting. 

And if you turn off momentum and turn off pulse (if present) does it cut the V to the engine ?

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Posted by el-capitan on Tuesday, March 11, 2008 10:50 PM

 cacole wrote:
If you are trying to run a newer Athearn diesel with a can motor, don't use that old power pack, or at least turn off the Momentum and Pulse Power switches if is has them.  The buzzing noise and headlight flicker you hear and see is because those old power packs were made to run the old Pittman open frame motors that drew a much heavier current than the newer can motors.  The can motor will be destroyed from overheating.

 Destroyed from overheating? I run open frames and pittman cans with old and new DC powerpacks on a regular basis and have never burned out a motor. The age of the motor doesn't matter. When the throttle is off, there shouldn't be a buzz. The throttle is the culprit.

 Check out the Deming Sub by clicking on the pics:

Deming Sub Deming Sub

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Posted by Anonymous on Wednesday, March 12, 2008 3:17 AM

Third or fourth time... I tried replacing the two electrolytics, a diode, and just by chance cleaning the main throttle pot with some D5 DeOxit cleaner and guess which procedure cured the problem? You guessed it. The easiest one.

Thanks guys for your help and suggestions.

Todd

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Posted by UpNorth on Wednesday, March 12, 2008 11:34 AM

That's why you allways start by the simple, then start burning bridges   ;-)

Good for you.

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Posted by Texas Zepher on Thursday, March 13, 2008 1:58 PM

 JoeinPA wrote:
It sounds to me that you may have a bad momentum capacitor. 
Actually no,  a bad capacitor would be the opposite problem.  A bad capacitor would have a lack of momentum action.

 jeffrey-wimberly wrote:
 GNTodd wrote:
$125.00 1983 dollars worth of brass Atlas HO rail. I wish I'd known about nickel rail. Maybe it didn't exist then.
Indeed, nickel-silver rail did exist then. I started using it in 1982.
The early 1980s is when the general population started discovering NS.  Atlas has actually produced it for as long as I can remember.  I've even got sections of NS rail on the fiber ties from the late 1950s. 

It takes a while (30 years in this case) for people in the general population to "discover" things. 

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Posted by jrbernier on Saturday, March 15, 2008 1:25 PM

  I was using Atlas n/s flex(the original plastic tie version was 2 ft long and darn near impossible to flex) and Customline turnouts in 1966.  IIRC, MR used this same trackage on their 'Ma & Pa' project layout in the mid 60's.

  I had some of the original brass flex on the fiber ties and it would swell up - the tie ends would curl up if you tried to ballast it.  This was all done on an old 5' by 9' 'ping pong' table and that was scrapped the following year.  If Atlas still sold brass track, there would be folks buying it.  There are folks looking for used brass track at train shows all the time.  I am not sure if they actually run trains or spend their modeling time cleaning track!

Jim

Modeling BNSF  and Milwaukee Road in SW Wisconsin

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  • From: Colorful Colorado
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Posted by Texas Zepher on Saturday, March 15, 2008 4:33 PM
 jrbernier wrote:
I am not sure if they actually run trains or spend their modeling time cleaning track!
I haven't noticed any difference in keeping one kind clean over the other.  I still wish we could get myth busters to take a look at that particular item.
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Posted by Anonymous on Monday, March 17, 2008 10:49 PM

Geez, guys! I'm sorry I didn't check back sooner. After I fixed the transformer I got back to my primary focus which is putting a new engine in my '86 Mustang GT. Did I mention I have no shortage of hobbies? Just time...

All of my track is U.S. made Atlas brass track from the early 80's. Not flex track - rigid with plastic ties. Lots of switches and switch panels. Most of it opened but I have almost all of the packages to it. Does it really have collector's value? Certainly not worth more than it's n/s replacement price?

Todd

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  • From: Colorful Colorado
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Posted by Texas Zepher on Tuesday, March 18, 2008 2:05 PM

 GNTodd wrote:
I got back to my primary focus which is putting a new engine in my '86 Mustang GT.
I've got an '83 GT convertible sitting in the garage.  It only has 12K miles on it though so no where close to needing a new engine.  Just a new top.   I sold my '68s a few years ago.  The convertible GT had some really bad rust and was beyond what I could repair with my resources.  Also had a '70 Cougar XR7 & '67 "original", but Collecting cars really consumes too much realestate.

I don't think the brass track necessarily has collectors value yet, that will take another 20 years or so.   It is just that people who want to use it are having a harder and harder time finding it, so the value has gone up.

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