My MTH K4 Pacific loses power (very briefly) when passing over an Atlas snap switch when aligned for the mainline, but does not lose power when the switch is aligned for the diverging route. It only does this when riding over one of many turnouts on my layout. I have six DCC equiped locos, and the MTH K4 is the only one that gives me this problem and only at one turnout location.
Any help in solving this problem will be appreciated.
IIRC, the Snap Switches have an all plastic frog. This will give you a momentary dead spot with a locomotive with a limited number of pickup wheels. Since this happens when the loco in question goes through the switch only one way, there’s one of two obvious possibilities:
The loco has a limited number of pickup wheels on one side.
The wheels are dirty and not all of them are picking up power from the tracks.
Check which side of the loco or tender is on the frog of the switch in question when it goes dead. I’m not familiar with the MTH locos and how their electrical pickup works, but the older ones had the loco pick up from one rail and the tender pick up from the other. Once you determine this, you should be able to figure out what’s wrong.
MTH decided to use pickup from the tender instead of the loco. Tender wheels are clean, I even replaced the turnout. I referred this problem to MTH and they have no answer. I appreciate your response, Tom. Thank you.
I would run a jumper wire from one end of the turnout to the other. If the engine was to blame, this would happen at all of your turnouts, since they are all the same size and geometry. Instead, your experience suggests that you’ve got a loose connection. My guess is a rail joiner. When this relatively heavy engine crosses the turnout, it momentarily loosens one of the rail joiners and breaks the connection.
You can test this with a simple clip-lead between the turnout and the connecting track. Remember, if it’s a rail joiner it could be on either the outer or inner rail and it will have the same effect. To figure out which one it is, run the engine very slowly until it actually stalls when it loses power, and doesn’t have enough speed to “coast” until it picks it up again. Press each of the joiners gently with a screwdriver until the engine gets power again. At that point, think about soldering the joiners.
Another trick is to run completely in the dark. You may actually see a spark jump the gap as the connection is broken and re-made.
Another quick way to check, I have a toy train power pack that I use for wheel cleaning on the bench. Touch the leads from the pack to each wheel tred on the tender that’s supposed to pick up power. The engine should run each time you touch one of the wheels with the wire. If not, you have a dead wheel. Also, if they use wipers on the wheels or axles to get the power from the wheel to the motor, check that the wipers are actually making contact. Unless they took the cheap way out, there should be a span of at least 1.5 inches between the pickup wheels for each side.
Another off the wall troubleshooting idea: turn the loco around and run it through the same turnout. Does it still stall on the same leg of the turnout?
Another thing that just came to mind: do you have insulated rail joints on the rails coming off the frog of this turnout? How about other turnouts that the loco runs through OK?
Tom: I’m on my way to the workbench to try some of your ideas. The loco does lose power in either direction on the mainline setting. I have no insulated connectors on my layout. The rail joiners are tight (new ones used when I replaced the turnout with a brand new one).
I’ll check the tender contacts. That seems the most likely cause of the problem.
This has been the most difficult problem I’ve encountered since I started in HO model railroading in December of 1950. Just goes to show that there is always something new to learn.
Thanks again for your input. I appreciate it.
Since you replaced the turnout and still have a problem, it is probably something under the track, a bump or something or a dip so the engine has a momentary problem.
I did a physical inspection of the tender’s pickups, which are soldered in place. Nothing was broken loose. I followed up with a continuity check, and that turned out fine.
After trying two methods of wheel cleaning (liquid and brush), I cleaned the tender’s wheels again with sanding film. That cured the problem. The loss of power was something I’ve experienced witht his model right out of the box. Seems like MTH needs to address this problem before selling the model.
Thank you so much for your input. Now I’m back to more scenery work and more fun with this wonderful hobby.