Sometimes when I run my MTH PS1 Zephyr, it starts moving with the horn blowing continuously for several seconds, which eventually stops. I've read the entire manual and found no indication that this is a programmable feature.
I usually use an RW transformer. The whistle and bell and engine sounds and station sounds work as intended. The Zephyr has a newer appropriate battery which is fully charged. An MTH PS1 Big Boy runs normally with sounds on my same Postwar transformers. Any advice?
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The horn blowing often indicates a DC offset in the voltage to the track.
If you have a Voltmeter, set it to DC and see if you have an offset.
(be sure to measure both polarities, Red lead to center, then to outer rail)
DC offset can be caused by a number of things but loading one side of the sine wave out of the transformer with diode restricted items is a prime example.
That is why you want to alternate the facing of the diodes when you add them in passenger car lighting, every other car then loads the opposing side of the sine wave.
Thanks Russell, I can check that when I get home, but I don't have any diode loads on the output. And other whistle units aren't affected; they need a definite DC offset to trigger.
Something that I just thought of ... I live off-grid and my 120vac is from a "modified sine wave" inverter, which runs most household appliances just fine. But maybe MTH electronics would be sensitive to an AC waveform that isn't "pure" sine wave? I would think a transformer probably smooths out "modified sine wave" somewhat, but I don't have an oscilloscope to look at it. I have a smaller-output sine-wave inverter, I could try that to see if it makes any difference ...
The other issues that can cause this are dirty pickups and wheels, dirty track, motor lead that is partially grounded to chassis and placing a DC signal on the AC side. Since yours is short duration I would try cleaning wheels and pickups well. G
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