On30 2-8-0 Motor HumI

[RGS Goose]

I purchased a Bachmann On30 2-8-0 some time ago which has only been test run occasionally up until now.
When I begin to apply power to the motor (using an NCE Procab system), the motor hums quite a bit before the loco moves. The hum slowly disappears as the loco accelerates. I suspect it is the chopped DC that our DCC systems feed the motors that is causing the hum, but do not know enough about it to know if it is the motor or the DCC decoder that is the real problem ( or both ).
Can anyone enlighten me as to the cause, and also tell me if there is a relatively easy way to stop this hum, as it is a bit annoying.
RGS Goose.

[ChrisS]

I have the same loco and my powercab system is on the way. I'll comment once I have some results for you

[railtwister]

You don't mention which decoder you are using, so I'll guess it's the OEM Bachmann one. Some decoders cause more hum than others, and I think some systems may do the same, since I have noticed no objectionable hum from Bachmann decoder equipped locos using my Lenz system. You might want to try one of the more 'upscale' decoders that feature supersonic operating frequencies, just to see if there's a difference. The hum will still be there, you just won't be able to hear it...

Bill

[rayport]

Problem could also be as simple as the starting voltage. If it is the OEM decoder the engine will probably not begin to move before step 5 or 6 (of28). If this is the case raising the value of CV2 to somewhere in the order of 25 to 30 may cure the problem and have the engine start to move at speed step 1 or 2.

[JohnR]

If you haven't run the engine much, it may need some break-in time.  The hum could be do to a stall state as it tries to get the wheels rolling.  The CV2 adjustment should help to get the start voltage high enough to get motion at speed step 1.  Give the engine a good break-in.  If you don't have a loop to run on, prop the engine up under the cab and pilot so that the drive wheels are above the rails.  Keep the tender on the track.  Run the engine in forward for at least 30 min.  Change the speed a couple times as well.  After the forward break-in, do the same thing in reverse.  While your at it, run it as slow as it will go and look to see if the wheel rotation is smooth.

Longer term, I'd suggest replacing the factory decoder with one from Digitrax or Lenz.  These have better speed control features and may offer quieter running. 

-John

[ChrisS]

my powercab arrived last night.
my bachman 2-8-0 does not hum at all with the stock decoder. it actually works well, i need to follow the above advice and change staring cv. its doesnt move until about step 11.

that being said, i installed a bachmann 8 pin decoder in my ams #50, and it doesnt work with dcc, just hums and wont move, the headlights work, but no movement..... so i ordered an nce decoder for it... it works in dc, so i'm assuming dead decoder... 

[rayport]

I had the same problem with my AMS #50. It was in their circuit board. Had to return the engine to AMS and now runs fine - except they need additional pickups installed, the usual problem with 4 wheel locos.

[ChrisS]

sorry to hijack.
rayport, you're ams 50 didnt work on dcc? mine just sits there and hums. i did install a $20 bachmann decoder, i am going to drop in an NCE unit when it arrives.

is it the loco, or the cheap decoder?

[rayport]

Mine was the AMS board. Tried several decoders which were all OK in other locos. The #50 also ran fine on DC, but nothing on DCC. Suggest that you contact Ada Ho at AMS. She was very helpfull to me.

[ChrisS]

Thanks. I just installed 2 other decoders and the same problem. I sent them an email
and will call in the morning.

[ChrisS]

well i talked to a couple of fellas at AMS this morning, they say i have the option(at their cost) to mail the loco to them and they will repair it.... but they didnt recommend that.
they suggested if i was willing and able, just to hardwire the decoder in and eliminate their board, but gotta keep the resistors for the lights.
so, i guess i'm performing surgery tonight!

[ChrisS]

Ok. Very simple fix once I looked at the board closely there are 2 solder contacts, unused. Labeled motor 1 and motor2. They have the track pickups going directly to the motor and to the board. Shorting the decoder. I moved the motor leads to motor1 and 2. And it's all better now