E-UNIT BUZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ

[Anonymous]

I have an MPC GP-20 (1980) with the old style electro/mechanical E-UNIT. The engine runs great and the E-UNIT sequences forward-neutral-reverse-neutral... fine. However, the E-UNIT buzzzzzzzzzzzzzzzzzzzzzzz is as loud as an electric pencil sharpener with a nail stuck in it! My question is, " Is it normal for the E-unit to buzz this loud?

[3railguy]

E unit buzz has to do with slop in moving parts. Some E units buzz more than others even when new due to sloppy manufacturing tolerances. Often times the stakes that hold them togther loosen. You may be able to tighten them. Some times the drum pins wear causing this. You can replace it. Check all moving parts for fit.

OGR's Barret in the Backshop, Vol 3 has a chapter on repairing these and he brings up this issue.

Repairing E units is tricky and can sometimes be more trouble than it's worth. There are special tools that make the job easier. Your best bet is to replace it with a QSI retrofit electronic reverse unit for around $30. It is quiet, reliable, and won't cycle into neutral on dead spots of track.

[FJ and G]

some guys actually enjoy the buzzing e-units; but not me;

don't care either for buzzing of 027 switches when trains are parked over them. I think making them DC powered would stop the buzz.

[lionelsoni]

Power the e-unit coil with DC through a small bridge rectifier, like the Radio Shack 276-1152 (1.4 amperes, $1.49). Remove the coil wires from the terminals that they are connected to on the side of the e-unit. Connect the bridge-rectifier terminals with the ~ symbol to these instead. Reconnect the coil wires to the bridge-rectifier terminals with the + and - symbols.

[Anonymous]

Thanks all for the very useful information. Think I will try the RS rectifier to energize the E-Unit coil first, and if that does not help go QSI with some sounds to boot!

[Anonymous]

QUOTE: Originally posted by lionelsoni

Power the e-unit coil with DC through a small bridge rectifier, like the Radio Shack 276-1152 (1.4 amperes, $1.49). Remove the coil wires from the terminals that they are connected to on the side of the e-unit. Connect the bridge-rectifier terminals with the ~ symbol to these instead. Reconnect the coil wires to the bridge-rectifier terminals with the + and - symbols.

Yep, this is the easiest way to go with a E-unit problem. They are so inexpensive, you might as well just buy another one![2c]

[Roger Bielen]

Dave, careful with parking cars on O27 switches for any length of time, that buzzing you hear is also heat being generated that'll melt down the selonoid. I've learned this through experience when I had an O27 layout.

[Anonymous]

The sound of an E unit buzzing is a reassuring sound to me. It reminds me of long happy hours as a child playing with my trains. It ranks with the scent of cookies baking, the warm colors of Christmas tree lights, 1950s music on the radio, and memories of my mom cooking supper and my dad coming home from work. It just makes me nostalgic for times long past and loved ones long gone. Odd-d

[daan]

The same problem with my e-units. They make noise like anything and I drive my loco's with the e-units shut off. I'll try the rectifier solution, otherwise I think an old marklin relais will do great too (They switch on overvoltage, like the relais from a horn/wistle).

[Anonymous]

I wired in the rectifies and it help a little. The rectifier alone just changes the 60 Hz buzz to a 120 Hz buzz, by putting all the cycles on one side of the zero cross over. By adding a 470 micoF capacitor across the DC output of the rectifier to act as a filter to smooth out the 120Hz bumps, negative to negative and positive to positive the buzz was finally eliminated all together. Then to get the E-unit to sequence a small switch must be added to one of the AC or DC outputs of the new rectifier. However! I noticed that after switching the E-unit over to DC operation that it ran MUCH HOTTER! To the point, I rewired everything back to AC operation at which point things cooled off. Therefore, I would recommend running engines with electro/mechanical E-unite with the E-unit turned off if the buzz is to loud or better yet go with a solid state QSI E-unit and add sound while you are at it. Overall, it was a fun experiment.

[lionelsoni]

George, I'm sorry I didn't say anything about a capacitor. I thought there was a good chance that full-wave DC alone would solve your problem and didn't want to complicate the answer too much.

The complication with using the capacitor is that the DC voltage at the coil is not the average of the unfiltered rectified sinusoid, but the peak, which is about 1.6 times greater. So, as you discovered, the power dissipated is about 2.5 times greater! You would have to have done something to reduce that voltage, like putting a resistor or a lamp in series.

I don't understand your comment, "Then to get the E-unit to sequence a small switch must be added to one of the AC or DC outputs of the new rectifier."

At least you had fun messing with it!

[Anonymous]

Bob,

I disconnected both ends of the E-unit coil and connected them to the - and + of the rectifier, bypassing the E-unit on/off lever.

George

[Big_Boy_4005]

I don't want to sound rude here, but could you please edit the word BUZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ down to about 10 Z's. The long "word" distorts the appearance of the forum screen when this topic comes up. Actually, it's kind of funny.[swg]

[daan]

It is meant to be as irritating as the sound meant by it..[:D][:D]

[ChiefEagles]

Toy Trains

[lionelsoni]

George, when I saw your recent post, I went back to look at this topic again.

I got out all my loose e-units and tried them on both AC and full-wave-rectified DC. Of 5 Lionel and 1 Flyer units, none buzzed on DC. The Flyer unit and one of the Lionels were even quiet on AC! These included normal gravity units and one horizontal-mounting, spring-return unit and one no-switch unit. The average DC voltage was 15 volts, about the same as the rms AC voltage, from a 1033.

Considering all this, I think that you must have an unusually loose and noisy e-unit. By the way, the fundamental of the buzz on AC is also 120 hertz, since the solenoid pulls up on the slug twice in each cycle, at the two peaks. Any difference that you hear is probably in the timbre, resulting from the changed waveform.