I have an Atlas N scale SD9 #53511 in the series; it has a grey frame, scale speed motor. It seems to run as though it has bad electrical pickup, or that it is on dirty track, or it has dirty wheels, etc. I have two other engines from this series (Espee tiger stripe; may be SD7, but basically the same engine) and they are so smooth that it is amazing. Thus, I deduce that there is something wrong with my #53511 SD9. I have cleaned the wheels, reassembled the trucks, gauged the axles, lubed the bearing blocks and gears, cleaned the track, checked the copper strip pickup, and everything else that is simple and can be done without disassembling the frame. My next effort is to remove the motor and check it out of the engine. Here is my question: As this is a decoder ready engine, can I remove the light board and have the engine still operate on DC power? Is the light board necessary for electrical pickup even in a DC engine? My ideas was to eliminate the possibility of cold solder joints or defective light board by hard wiring the motor (if it is good) to the frame like it was in the old days. Hope this was clear. This is my third post in the DCC & Electronics forum and I am growing more bold all the time. Should I check the brushes? This is a new engine. Also, the brass flywheels are slightly "smudged" with some type of corrosion. The "smudge" is a fingerprint. Not a factor in electrical operation, but I thought it was odd. Does that mean the commutator might be dirty, too? Thanks for the help on this.
Flash, I would check the motor contacts under the circuit board. It's the same thing that happens to DCC Atlas locos.:tb-biggrin:
If the design is like the MP-15 and SD-60s the motor gets it's electrical contact from the bottom of the light board. If the light board doesn't make contact with the motor pickups, the lights come on but the engine doesn't move or you can get a slight torqueing (flexing of the drive train) and the motor can momentarily loose contact with the light board. In either case, what I'd suggest is removing the light board, bend the motor contact strips up a little to ensure contact and close it up.
Try connecting DC power directly to the frame halves and see if the motor runs smoiothly. If it does, check the contact between the pickup strips and the contact nubs on top of the trucks. I had a loco where the nubs were dirty. Bending the strips a tad and a quick shot of contact cleaner solved the problem. If its still jumpy, check the motor contacts to the underside of the light board as suggested.
Flash: Check the motor contacts under the light board. Also make sure the contacts are properly contacting the trucks.
Did you DCC Forum guys all PM each other so you would give me the same answer? :unsure8ao: It was the contacts under the light board, all right. I didn't know this was how the engine received the track power. The strip connected to the motor pole on the top appeared as though it had been crushed down and only the top edge of the strip was partially contacting the light board. I pulled the copper strip back straight and then bent it into a "U" shape being sure the top of the "U" was higher than the bottom of the light board. The motor was very, very smooth when "jumpered" through the frame halves or through the copper truck pickup strips. I cleaned the wheel pickup copper strips just to be sure. Thanks guys! I learned something today. I want to ask my N scale buddies in my club if they have heard of this. On to the Ron Beardon mod on one of my two GP15s; I want to compare the difference the mod makes. This has been a very successful day and it's not even over yet!! :thumbs_up:
I have the same problem with my N scale Atlas SD9. It has a very poor motor voltage pick up design under the light board. You have to adjust the short motor contact just right to make good electrical light board contact. However, as the loco ages the contact looses it spring tension and then it starts the eratic movement you mention in you blog above. I bought a replacement motor because the short pick actually broke at the base where it meets the motor brush contact on top of the motor. I also had the same problem using an MRC #1812 dcc/sound decoder. I'm trying to figure out a way to solder the board contact to the short motor contact. I beleive this would be the only sure fix to continally supply uninterupted voltage to the motor. This is a quality issue that Atlas has to solve. I know I'll never buy another Atlas locomotive. Kato only from now on.
Here are instructions for soldering jumpers to those Atlas motor contacts. Works for the DC boards too. Atlas P&P BTW, good luck getting ATLAS to "fix" the problem. Digitrax told them the design was not the best and even recommended a minor design change to fix it. That was in 2003. Still waiting... Martin Myers
atlas china quailty martin: had the same problem with a B23-7 that was given to me. it ran great for about 2 years, and after that much time and after having been shopped about 5 or 6 times that short motor contact snapped at the brush. you bet it is a minor problem and slightly different forming of that contact would have prevented it altogether. i have suspended all purchases of new atlas locos, and we have far fewer problems with the older japanese-made locomotives at my club.
i looked at the fix and it seems fairly simple and straight-forward. however, soldering the new wire leads to the old motor contacts is not acceptable. the contact may break again farther down, after a new weak spot develops (and it will because the motor inevitably moves around- even with the 'clever' plastic mounting yoke) and there ya go- loco dead agin. now i see why the new atlas locomotives are so light in weight- harder to throw them through their front window!
Remove and solder the wires to the brush caps, now re-install the brush caps. While this is a wired decoder application, the wires to the brush caps work exceptionally well.
