Hi Guys, I have an MTH cab forward that I haven't used for a couple of months. My tender is humming after it warms up it becomes intermitten. Any ideas if anything is wrong?
Thanks Frank
Why is the MTH tender humming? Because it doesn't know the words...
Seriously, although I'm not familiar with this exact engine, would I be correct to assume that it has sound, and the speaker is in the tender? At any rate, the first thing to do is to figure out what is humming in the tender. If it is from a speaker, it could be a problem with a bad sound board, a bad filter capacitor on the sound board, or even a power supply problem. If you have other MTH locomotives and they don't hum, then we can probably rule out the power supply. If there isn't any sound in the tender, then you would just have to crack it open and investigate the source (which you will probably have to do anyway). I assume the engine operates normally other than the hum? Does the hum sound like a 60 hz powerline frequency? Any MTH owners out there with any experience like this?
- James
Sixty hertz is halfway between B-flat and B.
Bob Nelson
Bob,
No kidding, I have used a similar fact to estimate the frequency of noise when a scope was not available. My vocal range is from middle C (~256 Hz) to two octaves below middle C or about 64 Hz. 120 Hz is about in the middle of my range. It is not exact, but it gets me in the ball park. The only note I remember is that the A above middle C is 440 Hz. From that, and knowing that there are 13 half steps in an octave, you can figure out the frequencies of the other notes.
Bruce Baker
I would first check the solder joints on the pc card in the tender to make sure that none are broken. I am sure there are some filter caps on the pc board, and be sure to check the solder joints on the caps. Usually, they are rather heavy and if they are not well soldered to the board and/or glued down, they can break a solder joint. If you have a bad solder joint on a cap, you are probably going to get 120 Hz hum.
Bruce, it's 12 semitones, unless you're counting both the first and last pitches. In any case, the calculation is 12*ln(f/440)/ln(2) for the number of semitones above A440, the ISO 16 standard. This gives about -34.49 for f=60. Add 36 to move it up 3 octaves, and you have 1.51, halfway between B-flat and B.
Middle C at 256 is the so-called scientific pitch. It's about a third of a semitone flatter than the A440 standard, but close enough for government work.
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