American Flyer 303 stops after a few minutes of run time

[DisneyRR]

I picked up an old AF303 that's in pretty good condition.  However, after 5 minutes of run time, the loco will just stop.   No response at all if I cut the voltage and then give it voltage from the power pack (I'm running this DC since it's quieter).  I have to let it rest for a few minutes, and then it will run again for another 4 or 5 minutes.  The loco is not hot, so I'm assuming that the motor is ok.  I read a post on this site where someone's loco would switch into reverse.  That problem stemmed from the fingers on the reverse unit not making good contact with the coil.  From what I can see, the reverse unit looks "ok".  It also looks original,  My question is:  Do you think that I need to replace the fingers on the reverse unit?  Has anyone else seen this problem?  Thanks!

[Timboy]

Well, I could be just like your physician and tell you to just run it for 4 minutes!  Sounds to me like the problem is your transformer.

[richhotrain]

Doesn't sound like a transformer issue to me.  It sounds more like an issue with the motor.  Maybe the armature?

i would not suspect the reversing unit because once the engine is running forward, the reversing unit is out of the picture until the power is cut at which point the engine will pause.

The OP says that when it stops, he has to let it rest a few minutes, then he can restart it.  If the transformer was at fault, shouldn't he be able to re-apply power immediately in which case it should then run in reverse?   I wonder about that because if the transformer is cutting off, causing the reverse unit to cycle to pause, then immediately re-applying power should cause the reverse unit to cycle to reverse.

Lastly, if the transformer is intermittently losing power, a multimeter should be able to confirm this loss of power.

Just some thoughts.

Rich

[DisneyRR]

Tim & Rich:

Thank you for your replies.  I hadn't thought of looking at something other than the loco.  After Tim's reply, I did the following:

I swapped out the power pack that I was using with an old AF transformer (40 watts???).  And...the loco runs fine.  I ran it for 30 minutes and figured at that point that it'll run all day.  Reverse unit worked perfectly, too.

So, I tried my most powerful power pack (MRC 260 - 23VDC; 20VA).  This power pack has an overload indicator.  After a few trips around  the loop, the loco stopped dead, and the overload indicator was lit.  This is just a small 4-foot loop around the bottom of the tree, so I only have one feeder.  When the overload trips, I can turn off the power pack and then turn it back on, and the train will make another few loops before tripping the overload again.  So, I didn't have to let it rest for a few minutes. Just for the heck of it, I checked each piece of track with my multimeter (I'm using American Models track).  All is good.

This same power pack runs my HO layout without issue.

Bottom line:  my 303 runs fine on AC, but overloads the power pack on DC.  It baffles me.

The only reason that I prefer DC is because I have a caboose with a Santa flagman (Lionel 6-49046).  On DC, it's quiet.  On AC, I get the old AC "buzz".  I use DC with my Lionel accessories, too, just because DC is quieter.  I'm "assuming" that this loco has a universal motor, or it wouldn't run at all on DC, would it?

I don't know.  I'm stymied.  Worse-case scenario:  I guess I run it AC.  This is my first "S" scale loco, so I have a lot to learn. 

Thanks again to both of you for your help.

Dan

[richhotrain]

Interesting !

Let me direct my question at Tim on this one.

Should the OP be running a vintage AF open frame motor on DC in the first place?

And, when the loco stops, is the motor trying to recover?  Or, is the transformer trying to reset itself?

Rich

[Timboy]

Dan:

You're welcome!  Obviously, the HO power pack isn't robust enough to run an old vintage American Flyer loco with it's open-frame motor and a coil inside the reverse unit, along with the headlight and smoke box in the boiler.  However, what you could do it to get a rectifier at Radio Shack and wire it between the output leads of the transformer and the track leads.  That will convert most of the AC voltage to DC voltage to the track and everything should run just fine.  The only caveat is that you really should provide for some type of heat relief for the rectifier.  If you get the style of rectifier with a hole in the middle, you can simply bolt it to a square of flashing and that should provide an adequate heat sink.  You can make an even better heat dissipater by enclosing it in a box with vents and wiring a small fan in with it to keep it cool.  But don't simply put it in a box without a fan.  Power packs are made with either a heat sink, a fan or both.  Transformers usually don' t need them.  Of course, you can always buy a more robust power pack from say, Model Rectifier Corporation for instance.  They are not that expensive.  Some guys will take out the mechanical reverse unit and put a small rectifier in the tender as well as rectifying the track voltage.  With the track leads going through a cross-wired DPDT switch, you can reverse polarity of the track voltage and control the direction of the train.  Of course, you can always just put a small rectifier in that action caboose to quiet it down.  So there are quite a number of things you can do; more even than I have briefly outlined. 

Regards,

Timboy   

[richhotrain]

DisneyRR

I picked up an old AF303 that's in pretty good condition.  However, after 5 minutes of run time, the loco will just stop.   No response at all if I cut the voltage and then give it voltage from the power pack (I'm running this DC since it's quieter).  I have to let it rest for a few minutes, and then it will run again for another 4 or 5 minutes. 

Tim,

My question remains unanswered:  Why does the OP have to let the engine rest for a few minutes?

Is the motor trying to recover, or is the power pack trying to reset itself?

Rich

[Timboy]

Rich:

The motor is fine.  It's the power pack that quickly gets "tired".  Not enough wattage for the old vintage S Gauge toy trains; plenty for HO, tho.  It would probably be fine if the open-frame motor was swapped out for a can motor.

I actually have a reservation about using a rectifier to convert track voltage from a transformer.  My concern is whether or not the on-board circuit breaker in the transformer will still function.  I know plenty of guys use this technique, but I've never really heard expert advice on whether the transformer's circuit breaker will function if there is a dead-short on the tracks.

Timboy

[richhotrain]

Tim,

i gotcha, thanks for that explanation.

Rich

[lionelsoni]

The transformer's circuit breaker should still trip.  It should protect the rectifier as well as the layout wiring as long as the rectifier's rating is up to that of the circuit breaker.  Only the largest bridge rectifiers (line this one:  http://www.radioshack.com/product/index.jsp?productId=2062584&filterName=Type&filterValue=Rectifiers ) need to be mounted on a heat sink.

There is no reason not to run a universal-motor locomotive on DC, except for losing the whistle feature of a Lionel locomotive.  To replace the reversing unit and get reversing according to voltage polarity, install a bridge rectifier in the locomotive, feeding either the armature or the field, but not both.  The ~ terminals of the rectifier should be wired in series with the part that doesn't have the rectifier.  This rectifier should be big enough for practically any locomotive:  http://www.radioshack.com/product/index.jsp?productId=2062580&filterName=Type&filterValue=Rectifiers

[DisneyRR]

Timboy & Rich:

Ah...it's all starting to make sense.  I should have suspected that the power pack wasn't powerful enough to run this loco.  My Dad left me a 50's Gilbert Hudson (HO scale).  I bought the MRC 260 just for that loco, because none of the other power packs that I owned had enough wattage.

Anyway, you guys should join a forum and answer questions from other train enthusiasts (Ha!).  Seriously, your advice has been invaluable, and I appreciate it.

I may go the rectifier route.  I found another post where the response even listed a wiring schematic to show how to add it to the tender.  But, adding it (and a switch) between the transformer and the terminal track sounds cleaner.  By the way, I double-checked....the transformer that powers this loco without any problems is actually a 25-watt transformer.  That's it. 

Add a rectifier to the caboose???  Hmm...another option.  I never considered that.

Anyway, thanks again for all your help!  I learned a lot from this discussion.

Dan

[DisneyRR]

Bob:

Thanks for the reply, and for the Radio Shack links.  I'm still leaning towards adding a rectifier between the transformer and the terminal track.  However, if I decide to replace the reversing unit, now I know which rectifier to buy.

Again...thanks!

Dan

[Timboy]

Dan:

You're welcome and good luck.  

Bob:

Thanks for the info.  I always recommend testing the circuit breaker (among other things) on a transformer before putting it into use.  So I would recommend testing the circuit breaker after the rectifier and DPDT switch is installed as a safety check.  Last thing you want is a dead short that doesn't get mitigated somehow.  

Regards,

Timboy