Strange Locomotive Behavior

[GoCanes]

 I have become fairly proficient in replacing parts and repairing  HO and N locomotives (fairly minor stuff, like changing out engines, running gear, couplers and soldering repair).

What I have trouble with, is diagnosing problems.

What are (or where is) a good source)for routine/basic engine diagnosis?  

For instance, I have a Spectrum Dash 40 N scale Loco.

It quit running during break in (it's DCC ready but I'm running it on analog/DC), no headlight, no movement, no nada.

A few days later, I had it on my layout to re test, it still wouldn't power up, until another loco accidently crossed over the blocked section of the spur it was on, and it suddenly powered up, and ran perfectly AS LONG AS ANOTHER LOCO WAS ON THE SAME BLOCK.

So, absolutely no power when on a track alone, but if another DC loco is on with it, it powers up and runs smoothly.


No idea what to make of this.  (There is no track or power supply problem, it's the locomotive)

Thank you

 

[Desertdweller]

I've seen this problem before.

You can quickly check the operation of your locomotive by applying power leads from your powerpack to the loco's wheels, and see if it runs this way without being on the track.

I think the problem is in the track.  You likely have a poor electrical connection at a track joint.  The weight of the second locomotive is pressing down on a loose track joint, completing the circuit. Two locomotives weigh enough to do this, one doesn't.

Take a needle-nosed pliers and squeeze your track joiners together a little tighter

Les

[GoCanes]

It is  not the track, nor any external factors.    Still learning about DCC, so I don't know if it being DCC ready is the source of the problem.

The power leads to the wheels didn't have any effect either

Probably going to send this one in.  When it runs, it runs great.  Weird.

[poliss]

DCC Ready means it doesn't have a decoder. It's a standard DC powered locomotive that is ready to be converted to DCC by buying and fitting a decoder.

[GoCanes]

DCC Ready means it doesn't have a decoder. It's a standard DC powered locomotive that is ready to be converted to DCC by buying and fitting a decoder.

Well, that eliminates a problem with the DCC components. (I had assumed there was some added wiring or something in the DCC Ready locos)

Never seen this sorta thing before.

Nothing mechanical that I notice.  Has to be some sorta short? 

[phillyreading]

What being "DCC ready" may mean is that it has a wiring harness built-in but needs to have the DCC decoder chip or other electronic parts installed.
I had something that was supposed to be TMCC ready(O gauge) and all it meant is that it had a wiring harness connector installed to add TMCC to it.
The motor may need to have stuff done to it as well to be DCC useable.

Also in O gauge three rail, if an engine is in sleeper mode(not powered up) but power is to the track, power will flow through that engine as well, in plain English it will bridge an insulated section of track.

Lee F.

[NarrowMinded]

if there s no decoder there are jumpers where the decoder plugs in, check those jumpers,

But for the life of me I can't think of a reason why jumping the track with another loco sort of acting like a resistor on the track would make a DC loco run, EXCEPT for maybe the vibration from the other loco making the poor connection on the faulty  loco make contact....

NM.Jeff

[GoCanes]

if there s no decoder there are jumpers where the decoder plugs in, check those jumpers,

But for the life of me I can't think of a reason why jumping the track with another loco sort of acting like a resistor on the track would make a DC loco run, EXCEPT for maybe the vibration from the other loco making the poor connection on the faulty  loco make contact....

NM.Jeff

Weird, isn't it?