brass track, atlas #4 turnouts with snap switches.
I have one feeder wire for a 4x8 foot layout feeding the outer loop of a two loop layout, the outer loop is where the trouble is.
I realized that the engine speed drops slightly right after passing through a turnout placed just before the curve at the end (turn 1 if you are at Indianapolis 500) , travels at reduced speed for about 8-10 track sections, then after hitting the turnout on the other side (turn 2), it picks up again.
With no loco running, I placed a meter on the rails from the feeder wire and moved it along the rails towards problem turnout. Immediately after the crossing or the frog, i saw a 1.5 volt drop when i had my controller at 1/2 speed. All the way through the curve and up to turnout #2, same drop. After turnout #2 voltage back up.
I pinched brass joiners at turnout #1 to make sure they are tight. If i remember what I did correctly, this brought the voltage back up. Thought I had success.
Here is where I am confusing myself.
I ran the loco again and heard drop in engine speed still. I noticed that this happens at this spot - past the frog- when the loco passes. As it runs through turn 2 turnout, voltage and speed regain the 1.5 volts. does voltage normally drop in the track when the loco passes anyway because it is drawing energy? I dont think so but I dont know why it is happening.
Two problems one solution?
Replace the Atlas #4 with a non insulated turnout frog like Shinohara?
Did i miss observing something to locate the real problem?
Add a set of feeders to the slow down section of track. A voltage drop of 1.5 volts with no load on the track should not be happening. With a load (engine) that drop should increase as your observation shows.
Yes, just add more feeders. You still have a bad or loose rail joiner in there somewhere. Pinching it tight is only a temporary fix, as you runs trains it will work loose again, or another one will. You should probably have 4 sets of feeders around a 4x8, if the current set connect at the middle of the front straight, then you should have another set int eh middle of the back straight, and a set between truns 1 and 2, and a set between turns 3 and 4.
I agree that the problem is probably a lack of feeders, but since you said brass track, have you cleaned it lately? Cleaning is a chore that we all must deal with, but brass track makes it more important to keep the railheads clean. Nickel-silver track and brass track both oxidize just from contact with the air. But, the oxide of the NS track is electrically conductive, while that of brass is not.
Install feeders. Clean the track. And, consider soldering the rail joints if that’s practical.
To begin with, always test at full track voltage. Turn the controller all the way up and repeat.
When you use a DMM and check track voltage, without a load, it is an open circuit check. What you measured was open circuit voltage. This is an okay test but there are better ways. What you found was a loss of current caused by voltage drop.
Voltage drop is always caused by extra resistance. Loose or contaminated rail joiners, under sized wiring, suitcase connectors, cold solder joints, loose terminal screws are all potential sources of this resistance.
Switches, over time due to the way power is routed past the frog, can also cause a drop. You have confirmed that once the loco gets past #1 and until it gets past #2, you have a slow down. The DMM readings also show this.
You did have success - at raising open circuit or no load voltage.
When the circuit saw a load by running a train, it lost current. This is why checking open circuit voltage across the rails is just an okay test.
[quote user=“kgill”]
does voltage normally drop in the track when the loco passes anyw