Athearn PA Repair Help


catnippertom

catnippertom

That Oregon Guy
I mentioned a while ago in the "What are you buying this month" thread that I purchased a set of daylight cars with an Athearn Alco PA unit with it. The engine has been giving me some trouble. It seems to stutter quite a bit. I have run other locos on my layout and they seem to run fine but this one just doesn't want to make it through a full loop without being all the way on the throttle. I cleaned up the wheels and the contacts. I also lubricated all of the gears. Still having the same issues. A little less but still it won't make it a full lap. Any ideas?
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Ah the old blue box innards!
I’m no expert but I suspect you’ll get lots of responses to ditch the contact strip and solder wires, clean the wheels and those little square bushings in the bogies, and possibly clean the commutator where the brushes contact.
Oh, and while you’re up to your elbows in it check the brushes as well.
 
That's a pretty old model and no doubt corrosion has found its way into the entire electrical path.
As mentioned above, the wheels all the way up to the motor contacts need to be closely inspected and cleaned with a Doxit 5 type cleaner.
If you can find some nickel silver wheels to replace those terrible Blue Box wheels, you'll find you can run it longer than one lap without another wheel cleaning required.
 
catnippertom said:
I mentioned a while ago in the "What are you buying this month" thread that I purchased a set of daylight cars with an Athearn Alco PA unit with it. The engine has been giving me some trouble. It seems to stutter quite a bit. I have run other locos on my layout and they seem to run fine but this one just doesn't want to make it through a full loop without being all the way on the throttle. I cleaned up the wheels and the contacts. I also lubricated all of the gears. Still having the same issues. A little less but still it won't make it a full lap. Any ideas?View attachment 174536
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I would definitely cut the contact strip short and solder wires from each end to the contacts on the trucks. Be sure to clean the underside of the contact strip where it touches the top contacts of the motor, and be sure the contact strip fits snuggly to the top of the motor. Then solder the wires from trucks to the contact strip. You may have to remove the motor from the frame and be sure the contacts on the bottom of the motor are touching the frame securely.
 
Rico said:
Ah the old blue box innards!
I’m no expert but I suspect you’ll get lots of responses to ditch the contact strip and solder wires, clean the wheels and those little square bushings in the bogies, and possibly clean the commutator where the brushes contact.
Oh, and while you’re up to your elbows in it check the brushes as well.
Click to expand...
I am new to all of this electronic work/wiring so what exactly is the contact strip and what wires should I need to make that happen? And what and where is everybody talking about lol
 
catnippertom said:
I am new to all of this electronic work/wiring so what exactly is the contact strip and what wires should I need to make that happen? And what and where is everybody talking about lol
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There are L-shaped pieces of metal coming up from each truck (wheel frames). There is a piece of metal that runs along the top of the motor with double bends at each end of the strip, that rub on the underside of each of the metal pieces coming up from the trucks. This provides contact to the motor from the wheels on each truck. The problem with this arrangement is that electrical contact is not reliable. So the best thing is to cut the ends of the strip off just short of the metal pieces coming up from each truck. Get some relatively flexible pieces of wire (AWG 24 will do nicely), and solder a short piece from each end of the now shortened top strip to each of the truck metals. The top strip has two sortof s-shaped bends that form the clip that holds the strip to the top of the motor. Just be sure they hold the strip to the top of the motor.
 
The motor also has a similar copper strip underneath it, this receives power through the chassis it also needs to be firmly seated, if the motor "wobbles" you'll get intermittent contact which also can cause stalling or "stuttering" of the Loco.
 
bnsf971 said:
If you do try to remove the motor, be aware the motor mounts will probably crumble to powder if you disturb them. I'd pick up a set and replace them, even if the mounts don't fall apart. They're at least 50 years old by now.
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You might remove the motor and solder a wire lead and drill and tap for a screw in the frame, wrapping the other end of the wire around the screw. Then use some bathroom calk or epoxy the motor in place.
 
I ended up taking everything apart, cleaning and sanding everything down so it is in pristine condition. I put everything back together and it seemed to run alright for a bit. It took a lot of power to get it to run at a regular speed. After a little bit, it went right back to stuttering a bit. I will share a video once I get one to show what is exactly happening. Maybe that will help with trying to diagnose the problem.
 
catnippertom said:
I ended up taking everything apart, cleaning and sanding everything down so it is in pristine condition. I put everything back together and it seemed to run alright for a bit. It took a lot of power to get it to run at a regular speed. After a little bit, it went right back to stuttering a bit. I will share a video once I get one to show what is exactly happening. Maybe that will help with trying to diagnose the problem.
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Definitely sound's like a power pickup problem.
 
bnsf971 said:
If you do try to remove the motor, be aware the motor mounts will probably crumble to powder if you disturb them. I'd pick up a set and replace them, even if the mounts don't fall apart. They're at least 50 years old by now.
Click to expand...
You might remove the motor and solder a wire lead and drill and tap for a screw in the frame, wrapping the other end of the wire around the screw. Then use some bathroom calk or epoxy the motor in place.
 
catnippertom said:
I ended up taking everything apart, cleaning and sanding everything down so it is in pristine condition. I put everything back together and it seemed to run alright for a bit. It took a lot of power to get it to run at a regular speed. After a little bit, it went right back to stuttering a bit. I will share a video once I get one to show what is exactly happening. Maybe that will help with trying to diagnose the problem.
Click to expand...
Late to the party here.

First, talk to me about the headlamp. Does it stay nice a bright while it is stuttering or does it also flicker. A solid headlamp says power pickup is not the issue, a flickering headlamp says power is not getting to the unit let alone the motor. That should help isolate where to look. Of course, this assumes the headlamp is nice and tight in its seat.

Depending on the headlamp test....

That model looks in such good condition I would not take any drastic actions. I think it has to be something fairly simple. What concerns me most is that it is taking a lot of power, and the stuttering comes back. From the picture the commutator looks mighty bright, shiny, and even scratched (below). I would expect it to have a nice carbon color on it where the brushes are rubbing. Based on all that, I will guess it has a brush problem. Even possibly almost totally gone and the motor is running on the spring contact. That would account for erratic behavior and the change over time as it runs.
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Brushes are easy to find.
https://midwestmodelrr.com/ath90037/
 
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Here is a video regarding the PA
I meant to post this a while ago. I have noticed that some of my track work is not perfect but other locos seem to run alright on it.
 
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After watching your I believe you have a loose connection somewhere. . When the unit looses power the head light dims. In my opinion when the unit is in the turns the motor is shifting enough to break the to the frame. I would change out the motor mounts to the type that screw in on the bottom. I have had a similar problem and it worked for me. Now whenever I get a Athearn the first thing I do is change out the mounts. Good luck
 

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