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I have an Atlas Silver Dash 8-40CW.
I've installed a Digitrax DH163P in it.
The two ditch lights had their negative leads clipped off of the headlight lead and soldered to the function wires, with the positive common left intact and hooked to the light board along with the headlight.
The ditch lights work fine, the engine programs ok and runs fine, and there are no shorts. However, when the headlight is turned on, the engine starts making a weird but FAINT buzzing sound as if it was a DC locomotive on a DCC track. (not as loud as an actual DC loco on a DCC track, but the sound is very soft and very similar)
There are no shorts, no crossed wires, no contact between the motor and the truck pickups.
What could be causing the buzzing? (Last time I checked, LEDs don't make noise
)
try clipping the positive lead and wire that to the decoder light output. That might fix the problem.
Why do you say that? Is it because I'm running three LEDs off one common wire? The decoder has another pad for the common in addition to the wire coming out of the harness.
Could the bussing be coming from the Atlas circuit board? (it shouldn't be an issue as it was originally wired that way from the factory, I simply moved the negative function leads to be controlled by the decoder.)
It was just a suggestion to see if the atlas board was the problem and causing some interference. I always remove any boards the locos come with and hardwire decoders in, Never had any problems with buzzing or anything else. If you can just remove the led wire from the board without clipping the wire and jumping it to the decoder then try it and see if there is still an issue.
Is the decoder a positive or negative common?
The decoder is definitely a positive common as I've done many installations before.
The light leads plug into the factory board with plugs (connectors).
Can you have the head light on without the ditch lights ? If so do you still get the buzzing with only the head light on ?
Yes, I still get the bussing without the ditch lights on. The only way to have only the headlight on is to put the engine in reverse though....
Yes, I still get the bussing without the ditch lights on. The only way to have only the headlight on is to put the engine in reverse though....
Hi.
The reason I asked was because I thought that adding the three negatives together might be overloading some component on the circuit board. Usually a buzzing might mean an overloaded component or one on the way out. It could also mean a poor connection.
Can you trace where the buzzing is coming from?
If you switch off all lights do you still get a noise ?
Also with the body off run the loco in the dark to see if you can spot any poor connection which may spark.
The negatives shouldn't be overloading anything on the circuit board. Only the front and rear headlights have their negatives connected to the circuit board. The positives for all 4 lights are connected to the circuit board with three of them connected to one terminal.
I know that I didn't wire it in backwards as the LEDs light and the factory resistors are on the positive leads.
I'll try running it with the shell off to see if anything physical is going on.
I have experienced this same in a Kato SD40-2 ho scale unit. I replaced the Digitrax decoder with a NCE decoder and the unit runs like a watch. Needles to say, thats the last Digitrax decoder I will buy.
I bought the Digitrax decoder because it was the same brand as the club's system (Maybe I'm a little superstitious?)
That decoder will be swapped out for an NCE as soon as it arrives.
Let us know how it goes for you.
Very interesting information since I'm planning to buy and install a decoder now in an Atlas Dash 8-40CW loco myself. What NEC decoder did you get and what digitrax decoder did you have? Please keep us posted as I may need to practice the "learn from others" before I purchase my decoder.
Dave
The Digitrax decoder is a DH165P shrink wrapped chip style decoder with a 9-pin JST plug.
I sent NCE an old MRC decoder as part of their replacement program and hopefully they will send me the D13SRJ which (currently, the newest production), has 4 functions (which is really all I need. One for forward headlight, one for rear headlight, and two for the ditch lights).
Eventually it will be upgraded to sound when someone makes a decent sound decoder for it. (I don't like any of the GE FDL-16 decoders on the market today), although I may use it as a guinea pig for the Ulrich Models custom Loksound decoder.
Digitrax sound decoders are very "behind" when it comes to sound quality and extended functions.
I don't like QSI in general, but other people may beg to differ.
The Soundtraxx Tsunami sounds great, but you cannot physically play realistic sounds on a speaker that fits in an HO scale engine. (other brands digitally manupulate the sounds so that they are audible, but at a similar, but not the same pitch)
so for a basic decoder so you can MU a loco the Digitrax wouldn't be that bad. For a loco you want good sound and a lot of features your better off with the Soundtraxx.
I know the sound out of a 1" speaker isn't going to be that great but for what you can get in a HO loco the Soundtraxx is the best option?
Dave
Yes, soundtraxx has the most realistic sound. That's what made the FDL-16 so bad. Unless you can break the laws of physics, you can't get that nice GE throb out a 1" speaker.
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