Hi Wolf,
You are correct... the multimeter will pick up a direct short circuit across a wheel set but will not necessarily pick up a fault that is induced by the combination of the voltage and the electrical inductive load of the motor.
The motor voltage can cause a breakdown of whatever insulation value there is in the delrin gear, the air and any fine conductive material that is lodged between the two stub ends of the half axles. Hopefully it is a fault of the kind that is easily found with a multimeter.
Similarly crud can build up where the power tabs are near each other over the pivot and cause an intermittent short and creating heat when under running load but otherwise not show up.
Hope this and all of the above ( all correct by the way!) helps
Cheers from Australia
Trevor
MetrolinkFan I tried the best I could swapped the motor withna new motor with teh brass flywheels,Cleaned the wheens still sparks and overheats.Not sure what to do now I really wanted to run this locomotive.
I tried the best I could swapped the motor withna new motor with teh brass flywheels,Cleaned the wheens still sparks and overheats.Not sure what to do now I really wanted to run this locomotive.
I'm inclined to agree with everyone else. It sounds like you have a short in the wheels or the trucks. I know multimeters can be used to find shorts, it might be a good idea to invest in one. Most are reasonably priced and have detailed instructions with them.
A friend of mine had an SD50 - new motor and all which was also heating and running erratically with sparking - and I located it to the wheels where the split axle had a bit of contact from one side to the other, I thought through a wrongly spaced axle and crud arcing inside the axle gear.
The cure was simple enough We took out the axles and filed a small amount from the axle so that there was more of a split inside the gear. We also cleaned the gear so there was no residual hiding in there.
Having said that, the older motors do run quite warm by comparison to later offerings. The wide body of a PA would allow you to put in quite a size can motor drawing far less current ... perhaps a double sided Canon motor?
Good Luck
Regards from Australia
I need some photos of what your talking about,I posted a photo of my train I do not see my post,Why I do not know.
CHeck the wheels carefully and see if there are any bits missing. The original AThearn wheels are sintered iron - iron powerd is put in a mold and compressed under high pressure with high heat to for them wheel. They are rather rough and more prone to sparking even when in good condition compared to more modern nickel silver or nickel silver plated wheels, but they do have an advantage in that the rough surface gives better traction. This model almost certainly has the older outside bearing type, so you can't just pop in a set of modern wheels. NWSL used to have repalcement nickel silver wheels for both styles of Athearn locos, but with them closing up, I'm not sure where you could get the older style ones any more.
I've seen the sintered iron ones with small chunks missing in the trad as well as ones with a piece missign from the flange. It happens, expecially if the loco is well used.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Do you have photos of what your talking about so I can fix my loco?
I just thought of something to check out. Looking at the HOSeeker diagram, the axles must be insulated with the drive gear, two seperate wheel/axle pieces, with the drive gear in the middle, providing the seperation. This is how the newer axles work, also. Each wheel picks up power from the track, and it goes through the side of the truck.
I'm not real familiar with how the power is picked up and routed through the trucks with metal side frames. I have some of trucks in pieces, I'll take a look tomorrow and see just how they work.
In that area is got to be where your problem is. The axles, and truck sides have to be insulated from each other. The wheels on the engineers side are the "+" and the firemans (conductor) side is the "-" side.
Take a close look as it runs, with the shell off, and pin point exactly where the sparking is.
Mike.
My You Tube
here is a photo of hope it shows up.https://drive.google.com/drive/my-drive
Without some close pictures, it's hard to see what might be happening. It does sound like a short. Athearns are simple, it should easy to see the short. Have you ran it with the shell off, and watched closely?
The motor change didn't seem to make any difference. The bottom of the motor should contact the frame, along with the trucks, (via that little pin on the frame cross member and the metal plate with the hole on the truck), the taller power connection, that connects the trucks to the top of motor, via that metal strip, should both be on the engineers side of loco.
There's not much else to them.
Work on getting us some good cloe-up pictures,
Wish I could do more,
Sounds like a short, like the trucks or wheels are in backwards.
New York, Vermont & Northern Rwy. - Route of the Black Diamonds
protolancer(at)kingstonemodelworks(dot)com
OK, now I see what you have. I looked at the 1970 and the 75. About the only difference is the 75 has flywheels.
You still need to clean any old grease from the trucks, and worm gear, and clean off the armature, and, make sure the connection between the frame and the truck is clean.
About the only difference from the 1970 or the 75 version and the post I made earlier, is the brass blocks. Everything would still apply.
Shows us pictures, as soon as you can, with the shell off.
I switched over a motor usung the gold looking flywheel motor,Still gets hot wheels are clean.I have some new frames I will see what I can do.Thanks for the replies all.
I can help, I've sent you a pm. As a newbie, your posts are moderated, so they take a while to appear.
There is a sticky on how to post photos in the General Forum
Basically you need a free online hosting service like Imgur.com or Imgbb.com
Then you need to figure out how to generate a HTML link that ends in .jpg and use the photo icon above, or a BB link that you can directly paste in your text.
Henry
COB Potomac & Northern
Shenandoah Valley
MetrolinkFan Mine dose not have the brass squares just the wheels and gears.I want to put a photo of it here,But how do I do that so you see what my loco looks like?
Mine dose not have the brass squares just the wheels and gears.I want to put a photo of it here,But how do I do that so you see what my loco looks like?
Welcome to the forums! As Darth says, you need to take it apart and give a good cleaning, removing any old grease in the truck gear case, although, Athearn didn't use a lot, like some P2K's, but a good cleaning is in order, along with the worm gear.
I use LaBelle #106 grease when putting it back together. Just a little on the worm gear will spread out on the rest of the gears.
Check where the trucks meet the frame, as that is the negative side of the power pick up. The cross member on the frame, and the area on the truck that contacts the frame, needs to be real clean, and oil free.
Clean the motor armature, and put just a tiny, tiny bit of oil on the little bearing on each end of the armature. Just a teeny tiny bit, you don't want the oil migrating to anywhere else.
Clean off the wheels, and make sure the little square brass blocks on the axles are clean, and making good contact with the metal plate on the side of the truck, and the axles.
Run it in both directions, with the shell off, and look, listen and feel.
That's about it. Good luck!
The sparks are coming from oxidation or dirt on the wheels, so a good cleaning will take care of that.
For the problem with the motor getting hot, this is probably from the old oil and grease being dried up and putting excess strain on the motor. Adding fresh oil to the bearings and grease to the gears will help to free it up, and cleaning the old stuff off each part should make it even better.
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Help all I am back been long time since I have been here,I was here,I am having isssues with my Athearn HO Alco PA.I got this at a swap meet few years ago,When I run the engine the frame,motor get hot.And I also noticed that the wheels spark anything I can do to.Keep the frame,motor from getting hot and the wheels from sparking?