Can you help me figure out how t ofind the short circuit?

  Did you disconnect the Marx semaphore ?  Old Marx wiring could be the problem.

Usually the last addition to the layout, or last modification that was done is the root cause.

I always work in steps, turn the power on, check everything with power on , then proceed...

I bet its the semaphore....

Take the leads to the Marx off the the Z and check again. If it trips the breaker you have track power issues. But before you leap, IMO, the correct chase scenario here is process of elimination, so disconnecting the track and trying again with no load at all checks the transformer out. Add the Marx back in to confirm its operation. Then check you are using the correct polarity to trigger it (ie a hot actuator isn't near or touching a common on the track, more a tubular thing, but.....)

J Daddy and Choo Choo Mike - I disconnected the Marx and the problem is gone..... Now to see if it is worth fixing..

If the issue isn't obvious, like wires, take an ohm reading on the coil. No continuity or real low or real high would be bad.

Likely 4-8ohm , 2 would be suspect, under even worse.

  I think most Marx accessories like 15v., that's their normal accessory voltage on transformers.

Adriatic posted:

If the issue isn't obvious, like wires, take an ohm reading on the coil. No continuity or real low or real high would be bad.

Likely 4-8ohm , 2 would be suspect, under even worse.

  I think most Marx accessories like 15v., that's their normal accessory voltage on transformers.

Thanks.. good info.

It's an ohm per foot wire reading your guessing with so wire gauge and number of wraps give a pretty standard reading. My numbers are a guess.

   A coil short either: shortens the length of the circuit, often dramatically (low ohm), or opens ( zero cont.) , or barely conducts (very high ohm).

It a guess without unwrapping

does the signal have that burned smell? I was reading on line that the Marx signals use thin wire on the solenoids and that too high a voltage eventually melts the wire.

Not sure if 14 v is to much, but I would guess the solenoid melted and shorted, which kicks the breaker.

Which do you have, the #439 with a 74 on pole?

Moonman posted:

Which do you have, the #439 with a 74 on pole?

Yes, that is the one I have.

Yes, the burnt smell even differs slightly on coil vs wiring. The coil wire is lacquer coated vs rubber so they stink different too.

Id guess vibration and age are to blame over 14-15v or they would have a rep for burning up when new and supplied with a new Marx transformer. But over that 15v mark, I wouldn't balk at agreeing because that 15v is the max voltage Ive seen on a Marx trans.

  Imo vibration wearing out lacquer is the #1 failure on most linear coils of any type, trains, HVAC, games, washing machines, etc. Heat, causing lacquer to crack overtime, then failure, is a far second but not impossible (or if you include combo automotive starter motor/solenoids, I think the engines heat kills the extra heavy lacquer coating there)

Marx engines run on low voltage so their coils were not wound with heavy wire. On a Lionel oval layout the coil can overheat and burn out.

Adriatic posted:

A coil short either: shortens the length of the circuit, often dramatically (low ohm), or opens ( zero cont.) , or barely conducts (very high ohm).

A major factor with a coil short is a shorted turn.  The resistance of the coil looks normal, but that shorted turn acts like a transformer secondary with a direct short.