The BLI Buzz?

[spookshow]

Has anyone ever figured out the source of the slight buzzing emitted by PCM/BLI diesels? They all seem to generate it to one degree or other (or at least all the ones I've owned have), and I always thought it had something to do with the traction tires. However, I finally tried swapping out the TT-equipped wheelsets on an Alco PB and it didn't help, so apparently the sound is caused by something else.

I've also tried lubricating the truck gears and the worms, but that didn't make any difference either. Anybody ever dug into this? It's not particularly annoying, but I wouldn't mind eliminating it (if the solution is relatively simple).

Thanks,
-Mark

[peteski]

Thus would not be related to a DCC buzz, right?  It is a model without a DCC decoder?

[spookshow]

All of mine have sound decoders, but I don't think it's an electronic buzz. It sounds mechanical to me.

-Mark

[C855B]

Hmm. Pete brings up a good point. I have not noticed any buzz. Mine (four E9's) were non-sound, and I installed TCS decoders. Have you tried unplugging the speaker? Do they buzz on DC?

[spookshow]

I really think you guys are barking up the wrong tree. The sound is evident with the speakers turned off.

-Mark

[C855B]

Ahh... but turned off via a function, or actually disconnected? If they're still connected to the circuit "controlled audio" off or not, they're vulnerable to any stray micro-currents floating around - even the dreaded "ground loop".

[spookshow]

No no no no, it's not the decoder. Try a new theory.

-Mark

[Bob Bufkin]

Sounds like something electrical to me.  None of mine have that sound.

[C855B]

Are you talking about the near-musical hum that varies in pitch with the speed? Then I have no idea. Sounds like a fan noise, but I know it's not. All of yours evidently do it, I've never noticed it.

[C855B]

Are you talking about the near-musical hum that varies in pitch with the speed? Then I have no idea. Sounds like a fan noise, but I know it's not. All of yours evidently do it, I've never noticed it.

But again, is the speaker disconnected?. If it's connected then there remains the possibility of chassis currents playing games.

[spookshow]

I unscrewed the speaker and decoder and moved them away from the engine. Running that way, the sound still comes from the engine (the trucks actually, or so it seems) - definitely not the speaker.

The sound I'm talking about is what sounds like "ticking" in the video soundtrack. On my side it sounds like a slight buzz.

-Mark

[peteski]

My original suspicion was that the sound was caused by the DCC circuitry driving the motor with pulsating (PWM) DC (as most decoders do), not a noise from a speaker of a sound decoder.   You know, the buzz emanating from a motor when it is driven by pulses.  The only way you could try to verify that would be to totally remove the DCC decoder from the model and run if using a pure DC signal (like a standard 9V battery).

[Bsklarski]

Sounds like gear noise to me, but then again what do I know 

[C855B]

OK. It's what we hear as clicking. Frankly, at this point you've got me. Like I said, mine don't do that... just normal noises.

[DKS]

Based on the video, it sounds like ordinary gear noise.