Transformer issues

[lionelsoni]

There are two main considerations in selecting a VOM ("multimeter"):  Analog or digital, and "true RMS" or not.  The first consideration is very subjective.  Digital meters are usually more accurate, while analog meters give a better indication of changes in the quantity measured.  (I prefer analog.)

A true-RMS (root-mean-square) meter reads the square-root of the average of the square of the instantaneous quantity, which is the usual way of describing alternating voltages and currents.  For a resistive load (like a lamp or a heater) it is the equivalent DC quantity corresponding to the same power consumed by the load.

For example, the power-outlet voltage used in North America is described as 120 volts RMS.  But during every cycle it is instantaneously more or less than 120 volts.  The peaks of the sinusoidal waveform are actually 170 volts.  Most VOMs are designed to assume that the quantity measured is sinusoidal and put out the wrong value otherwise.  Some, the "true RMS" ones, give the right answer for all waveforms--and are much more expensive.  I would stick with the cheaper kind of meter, but be aware of its limitations.

Some years ago I posted the following chart for correcting a typical meter's voltage reading for the Lionel CW-80:

 Meter           RMS 
  0             0
  0.5           1.6
  1             2.7
  1.5           3.7
  2             4.6
  2.5           5.4
  3             6.1
  3.5           6.9
  4             7.5
  4.5           8.2
  5             8.8
  5.5           9.5
  6            10
  6.5          10.6
  7            11.2
  7.5          11.7
  8            12.2
  8.5          12.7
  9            13.2
  9.5          13.7
 10            14.1
 10.5          14.6
 11            15
 11.5          15.4
 12            15.8
 12.5          16.2
 13            16.6
 13.5          16.9
 14            17.3
 14.5          17.6
 15            17.9
 15.5          18.2
 16            18.5
 16.5          18.8
 17            19
 17.5          19.3
 18            19.5
 18.5          19.7
 19            19.8
 19.5          19.9
 20            20

[teledoc]

You can get a cheap one from Harbor Freight under $10.

[Flintlock76]

A multimeter is a very  handy thing to have in this hobby, trust me!  If you don't have one, get one, there's some reasonably priced ones out there that won't bust your budget.

And don't be surprised if that Marx transformer's died on you, it's been known to happen.  Happened to me.

[TrainLarry]

Does the engine run with another transformer?

If you have a multimeter, set its range to read 20 volts AC and check for voltage at the terminals.

If there is a headlight on the locomotive, or if you have a lighted car, it should light.

Note that a 50 watt transformer is very small, and will only run a small locomotive. A large locomotive may barely run.

 

Larry

 

[Conkeeper89]

K, thanks so much

[teledoc]

Simple answer, is use a multimeter, to see if there is any voltage at he output.  The wattage means nothing, without having voltage at the output.

[Conkeeper89]

I have a Louis Marx transformer with a 50 watt output. How do I troubleshoot it to see if it works? My engine won’t run at all currently with this transformer