one of my old DC Athearn (GP9) fell and broke apart. After some messing around, saw the front truck had lodged too far forward. Made some adjustments to free the truck.
Putting the chasis on the work bench, took transformer power and applied directly to the commutator and one of the leads that powers the light. The engine roars to life. Put it on a test track (different transformer) that it crawls for a while, occasionally stops. I can press the conducting link across the top of the engine and it will start running. So what is the likely culprit? Is the loss of voltage that significant between track power vs directly powering at the commutator? I'm figuring something is loose somewhere, but can't pinpoint it.
cap3344I can press the conducting link across the top of the engine and it will start running.
Are you talking about the metal strip that connects each truck with the top of the motor?
Carefully remove the strip, and make sure it's clean, where it contacts the brass strip on the top of the motor.
Also make sure it is clean where the strip contacts the truck, on each end.
cap3344After some messing around, saw the front truck had lodged too far forward. Made some adjustments to free the truck.
What did you do for "adjustments? The frame has a little pin that fits into a hole on the truck. That connection, between frame and truck must be real clean.
That is the "minus" (-) side of the electrical supply to the motor.
How "old" is old? Are the sideframes, on the trucks plastic, and removable?
Is there a little sqaure brass block that the axle goes through, on each side.?
Also, with the shell off, and both trucks correctly in place, place the loco on a mirror, (something perfectly flat) and try to slide a piece of paper under each wheel.
This will tell you if the frame got bent from the fall.
Also, you can eliminate the metal strip across the top by soldering a wire from each truck to the brass strip that is on top of the motor.
When you remove that strip, for soldering, be extra carefull, as that strip holds the top brush in place, and if your not carefull, the brush spring will launch into space.
Mike.
My You Tube
The contact between the metal strips on the motor and the trucks on Athearn locomotives is notoriously an intermittent problem source.
.
Since you have it apart, the common solution is to run a short wire from the metal motor bar to the truck bar.
Sorry, I do not have a picture.
-Kevin
Living the dream.
Thanks, going to have to dig a little deeper into this. How old - don't know, came from my Dad's collection... so 20++ years I suspect. Including a picture here (if I linked in Dropbox properly)
Not one we can see. edit here's the google pic, if it stays. The times I've tried this before, it becomes invisible
Henry
COB Potomac & Northern
Shenandoah Valley
No picture. I don't how to use Drop Box, so i can't help.
Read the Tutorial on how to post pictures, at the top of the General Discussion forum.
mbinsewi No picture. I don't how to use Drop Box, so i can't help. ...
...
If you use a Gmail Account, you can upload a picture to Google Drive and copy the link from there. If you need a tutorial on using Google Drive, PM me with your email address.
Cheers from Australia
Trevor
Thanks Trevor, but no thanks. I was just responding to the OP.
I use PhotoBucket, and I'm very happy with it.
This link worked for me
https://2d319997-a-62cb3a1a-s-sites.googlegroups.com/site/steveattias/videos/home/GP9_IMG_0394.jpg?attachauth=ANoY7cqGu_eLL9r_hE0_Fi7N2R9_jrYoB1UZ8l_vEzUK0Cepf11xjWVwd5rUSpSulV2XkxKfgBzbInrn0ee3H2PrWlegtmBXYAfbEmNq45YGmWxPR7fGCoVRLi9a_fkliqx2I6tSbVdhZNtUzjh85Qla-7FHvOCBX8SnJuo0CEKpy-Ehk6pM2JMtBn7BTnx-WMIbADoMUBEwyKuS4jJebnvwMAb6K9BxDDO-wVyd6Zru-GWyh4lQ7QY%3D&attredirects=0
mbinsewiThis will tell you if the frame got bent from the fall.
Mike,From my two experiences the frame doesn't bend it breakes. Sadly I learn that from dropping a BB GP7 and SW7.
Thankfully that was back in the day when LHS actually stock parts. I shudder at the idea of needing a GP7 or SW7 frame today.
Larry
Conductor.
Summerset Ry.
"Stay Alert, Don't get hurt Safety First!"
OK, Henry's picture works, the OP's link doesn't.
Anyway, you have a "newer" model, from the 80's & early 90's.
So check all of the items that have been addressed in earlier posts, and when you get back, trouble shooting can continue.
Also describe, as I asked before, what "adjustments" you did to the front truck?
EDIT: That is true, Larry. Whatever they are cast from, breaks before it bends.
Hello All,
Sorry to hear about your unfortunate mishap.
Do you have a multi meter with a continuity function (beeper)?
If the loco landed on it's wheels definitely check the two prog-type contacts from the clip on the bottom of the motor to the frame.
A severe enough hit could push the motor down and flatten these contacts enough to cause intermittent running.
If it landed shell side down then the culprit might be the contact strip from the motor to the top contacts of the gear towers.
This contact strip might have been bent upwards and need some "gentile persuasion" to re-establish the electrical paths.
When removing the top strip- -as has been mentioned- -be careful to not loose the brush spring.
Using your meter put one probe on the wheel and one probe on the related contact on the motor and move the trucks around to see if you can reproduce a break in electrical continuity.
If you do decide to bypass the upper contact strip you can cut off the ends that contact the top of the gear towers, while retaining the center section that acts as the clip to hold the spring and motor brush in place.
The frame will still act as the electrical path, through the bottom contacts, to the motor.
If this were mine I would commit to isolating the motor from the frame entirely and wire from the trucks to the motor directly.
One trick I used to isolate the motors in my BBs was to cut off the ends of the top strip and swap that clip for the bottom one, after flattening the prongs of the bottom strip.
For added piece of mind I also cut off the horizontal part of the gear tower contact and soldered the wire to the side.
I also cut off the contact strips from the trucks to the frame and soldered the wires to the side of the trucks.
The I used Kapton tape on the bottom motor mount to provide added electrical isolation between the frame and motor.
This will make running on DC more reliable.
If you do decide to completely isolate the motor from the frame on this, or any other BB that you have, converting to DCC will be much easier.
Good luck, and as always...
Hope this helps
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
Thanks to everyone , lots of great advice. Probably not going to tackle this until after the holiday but now I have at least a clue. Pulled an old truck apart, so I can see how each side power gets to the chasis and motor. I suspect the bottom tabs on the motor are a problem. I will consider doing the solder/wire suggestions - my soldering skills are still growing. Lots oto learn, just this unplanned event is taking time frmo other projects - including some initial landcaping on my little 4x8! Agains thanks to all and have a great Memorial day holiday!
Back after the holiday... I haven't done any rewiring, just working with trucks and motor mounts and electrical connections between. I get the loco running consistantly, but very slowly, even at ~18v. I've got a spare engine and flywheels that runs noticeably better. I want to swap that in first and see if it gets any better results with the current frame and trucks. If it runs better, then I can isolate it to the original motor and I'll probably try my hand at a complete overhaul. If it still runs poorly then I'm going to say the chassis/trucks are an issue, either connectivity or perhaps the frame is causing some binding. I still like the idea of rewiring the connections between the trucks and the motor. going to try this on at least one of these.
Not Athearn geeps, but rather Athearn SWs modified to represent SW1200RS locomotives...
All of the locos have extra weight added, and in addition to being very smooth runners, they're also exceptionally good pullers for their size, seen here at the head of a 71 car train, which they easily handled up a curving 45' long 2.8% grade...
Those older Athearn frames can be straightened, but they need to be completely stripped-down so that they can be placed in a vise....hammers are not recommended.
Wayne
Great idea... this is a DC set up? Did you isolate the motor from the chassis too? I think I'm going to try a LocoFI setup, so this would be real useful. What gauge wire did you use here? Thanks.
Did the motor/flywheel swap this morning. It's running a lot better now, so I'm setting aside the original motor for a lesson on rebuilding a motor. have another GP9 I'm going to look at for rewiring and motor isolation. Thanks to all for advice and suggestions. Considering this as lesson learned (be more careful stupid) and closed case!
cap3344 this is a DC set up? Did you isolate the motor from the chassis too?...
Sorry, I should have mentioned that it's DC operation, so there was no need to isolate the motor. For DCC, it would be easy enough, though.