MRC Railmaster - Overload keeps tripping

"BSwabby" wrote in news:7cb3ad6070581@uwe:

Do you have a multimeter? If not, spend $10 and get one.

Got one? Good. Disconnect the power pack and set your multimeter to OHMs. Place one lead on each rail, and take a reading. There should be infinite ohms resistance between the rails. ANY non-infinate reading means some how there's an electrical path. (This is more or less a sanity check.)

Now, connect your power pack and set your meter to VOLTS DC. Without the engine on the track, measure the voltage at the source and the farthest point away from the voltage, as the rails run. This should be the half way point with one set of feeders. You should get the same voltage reading at that point. If you don't, you have something creating resistance (either distance [unlikely] or rail joiners). The solution is to add more feeders.

You are running the same engine both times, right?

Puckdropper

Well, no, with one set of feeders you *won't* get the same reading there.

Even if there are no other problems, it will be caused by the distance through the rail itself. Depending on the track being used (nickel-silver, brass, steel, etc) the actual resistance through the rails can be quite high. For example, folks like nickel-silver track because "it doesn't oxidize" like brass track does. But it's resistance per foot is higher than brass track, and much higher per foot than properly-sized copper wire. (And actually, it does oxidize. It's just that unlike brass, nickel-silver's oxide is conductive.)

Again, assuming there are no other problems found, that would be a true statement. And it would be A Good Thing To Do even if other problem(s) ARE found and fixed.

Stevert

With no load other than the meter the voltage should be the same.

Ya know, we all forgot the obvious. OP are your railjoiners tight and the track and wheels of the loco clean?

Dirt wouldn't explain why the power pack's overload protector trips. That implies a short somewhere.

IMO, and the experience we have had at the club, counting on rail joiners for electrical connection is a mistake. Rail joiners are for alignment, drops are for electricity. We went through our layout a couple of years ago and made sure we had a drop to EVERY section of track. A good many strange behaviors just don't happen any more ... ok we still have some strange behaviors but, connectivity isn't likely to be the cause.

Paul

Are you using the same engine and cars on both loops. Does all of you equipment work on the working loop? Add cars one at a time and energize the track.

Make the resistance measurement as suggested. With nothing on the track, the reading should be infinite (unless your meter is set to measure multi-megaohms, in which case it should still be very high.)

If the reading is not infinite, open the track circuit (separate the track) in 2 places and test each section. Repeat the process on the (any) section that reads low. The process is divide and test (conquer).

What happens when you energize the track with nothing on it?

Are both loops connected to the variable DC output?

Make the voltage measurement that someone else suggested. With no load (no engine or illuminated or otherwise powered cars) on the track, the voltage should be the same everywhere. This proves that the track itself can be energized and that the circuit is continuous (and the problem is in the engine or cars).

Good luck

snipped-for-privacy@mail.wan.vpn (Paul Newhouse) wrote in news: snipped-for-privacy@corp.supernews.com:

That's fine for flex track, but what about sectional track? That's an awful lot of feeders. You may want to look in to something like soldering rail joints with sectional track instead.

I don't have any electrical problems with my soldered rail joints and 2 feeders every 4' module. It's when I don't get those extra feeders that I start to have trouble!

Puckdropper

That's a lot of soldering *8^)

BZZZTT! Wrong answer. The resistance of the rail *is* the load, and will result in a voltage drop at the far end of the layout. Please see the resistance tables Mr. Gartner has kindly assembled for us:

Stevert wrote in news:kT09j.7971$ snipped-for-privacy@nlpi069.nbdc.sbc.com:

Ok, looking at the web page you linked: Using #18 feeders, the voltage drop at 1A is apparently .010 volts per foot. Let's say the wires run 10', so you've got a voltage drop of 0.1 V. That's well within the tolerance of a $10 meter. (There's more than stated tolerance to just how accurate your meter is.)

Now, let's look at code 100 track, same amperage and same run.

In this case, "the same" should be interpreted to mean "close to the same, but with an implicit tolerance of around +- 0.5V."

Puckdropper

How much current does your voltmeter draw? Mine is in the micri amp range.

Sorry Wrong answer!!!!!!!!!!!!!!!!!!

The 'Rails' are just conductors. There needs to be a 'load' [Loco, light bulb, unwanted Short Circuit] before the 'resistance of the rails can have ANY effect on the voltage available.

Chuck D.