Dilemma with Bachmann N-scale S-4's

[SP-Wolf]

Howdy,

Have an interesting problem. Don't know where to turn- so- here goes.

Yesterday while trying to program my new Bachmann N-Scale S-4's (First with the stock decoders- then with DZ125's)--Yes- I changed out the factory decoders. I kept getting "NO PG" on my DT400. When I tryed with the Bachmann decoder I figured it was just an issue with them. But- when it happened after changing out to the DZ125's and- the same message came up. I was/am stumped. I did program the DZ125's (2 of them) thru JMRI. A new issue came up- I wanted to set them up for rule 17. I programmed CV 49- to 104 and CV 50- To 024. The head lights work great. The rear's do not work at all. Off of the locomotives- the LED's work fine.

Sorry, for combining my issues, thanks- for any pointers/help,
Wolf

[peteski]

I think that message indicates that the command station does not see the decoder. The decoder communicates with the command station by placing an electrical load across the track power leads.  Decoder uses the motor as that load.  Maybe the Bachmann motor does not provide enough of a load (its resistance is not low enough) to be a sufficient load.  You could try to temporarily install an extra load in parallel with the motor to see if that makes a difference.  Somethign like a 100 ohm 1Watt resistor should do the trick.

That makes me wonder if Bachmann is again using a coreless motor in their locomotive.  Coreless motors in general are very efficient and they draw very little current.

[SP-Wolf]

Hi Peteski,

This is very interesting indeed. I will have to give that a try. This is the first thing that I have heard that makes any kind of sense. 

Thanks!!!
Wolf

[reinhardtjh]

Even if the motor isn't coreless the Bachmann decoder might not be pulsing it enough to show a load to the command station.  Although the DZ125 should so it could be the motor.  As Peteski says, the common fix is to put a resistor across the programming track to increase the current flow.  Typically a 1K ohm is sufficient.  The 44-tonner is notorious for needing this.

[sizemore]

You can also use a 12v lightbulb. I typically have a mothballed old school Bachmann Spectrum F-7A sitting on the programming track to create the necessary load.

The S.

[peteski]

You can also use a 12v lightbulb. I typically have a mothballed old school Bachmann Spectrum F-7A sitting on the programming track to create the necessary load.

The S.

Really?  Simply placing the bulb across the programming track (in parallel with the locomotive) works?  That creates a constant load across the programming track.  In order for the decoder to properly acknowledge programming commands, the load needs to be introduced by the decoder, after it receives the command.

Hmm... but if that works, maybe the additional constant load across the programming track is below the threshold of what the command station needs for acknowledgment current. Then the added load of when the decoder sends its real acknowledgment is enough for the command station to properly recognize the acknowledgment.

[SP-Wolf]

Good 'ol Bachmann--The polarity is marked backwards. I reversed my wiring (Putting the blue wire and resistor to the negative side) and th rear light now works as it should.

Thanks,
Wolf

[trainforfun]

Good 'ol Bachmann--The polarity is marked backwards. I reversed my wiring (Putting the blue wire and resistor to the negative side) and th rear light now works as it should.

Thanks,
Wolf

Wow ! I would have never tought trying that !

[mmyers]

Placing a load like a light bulb, 1K ohm resistor, another DC engine, etc. will increase the load when programming. Although the load is always on the track, power is only applied when the programmer is programming. There is no voltage on the programming track when the Zephyr's programmer is not actually programming. The ack produced when the  low current spike of the motor  occurs is enough combined with that extra load across the rails for the programmer to notice.

A stock S4 decoder on our Digitrax sytem at Bedford on Saturday. No extra load applied. mGuess it's the luck of the draw.

Martin Myers

[SP-Wolf]

Placing a load like a light bulb, 1K ohm resistor, another DC engine, etc. will increase the load when programming. Although the load is always on the track, power is only applied when the programmer is programming. There is no voltage on the programming track when the Zephyr's programmer is not actually programming. The ack produced when the  low current spike of the motor  occurs is enough combined with that extra load across the rails for the programmer to notice.

A stock S4 decoder on our Digitrax sytem at Bedford on Saturday. No extra load applied. mGuess it's the luck of the draw.

Martin Myers

Howdy Martin,

It is odd. I am using the DCS200 Super Chief 8 amp. This is the first time I have encountered this sort of thing. So- I just used JMRI- problem solved.

I will be trying a 1K ohm resistor- just to see if that solves the problem. I gots ta know.....

This DCC thing does keep ya on yer toes!!

Thanks,
Wolf

[ksmiley]

Hi all,

I know this post is quite old but I picked up a N Scale Bachmann S-4 off E-Bay recently and using a Digitrax DCS51, the little all in one box, I kept getting 'dnr' Decoder Not Responding messages. I thought the decoder was toast so was considering clipping the wires off and installing a DZ123. However, after reading this a having a non-decoder DC loco on the programming track with the S-4, it took a new number and I was able to run it just fine.

I do want to say that these locos seem to have a lot of factory grease on the wheels and it took a while to get it running smoothly on my test track. I wouldn't recommend taking this model to a train show without some in-private running time first. I read on Spookshow that this loco uses wipers on the back of the wheels for power pick up. Be sure to clean the wheel backs as there was a lot of residue from the factory which impacted the pickups.

Anyway, just wanted to add to the body of knowledge. The earlier posts here were quite useful.

Kent

[EL3632]

The "needing to add resistance" to a programming track is an extremely common issue with older decoders, particularly old Lenz decoders put in Atlas locomotives from the factory. I typically put an LED track test light on the programming tack to add resistance. My current programming tracks for JMRI and Lokprogrammer are Kato Unitrack with some of the lit bulb track bumpers on each end, to provide resistance where necessary. I have not had any issues programming whatsoever with the bumpers, other than dirty wheels or dirty track.

[ksmiley]

Hi Again,

Further to the above, once I got a new loco address on it and running on the test track, it took a while to get running somewhat smoothly. Something didn't seem right so, out came the multimeter and I started checking connectivity between trucks, wheels, and the DCC board. Turned out, the two left side trucks were not connected. Each truck was connected to the board individually, so the wheel back wiper pickups were ok, but only the right side wheels had front to back truck connectivity. On the DCC board the right side had connectivity between where the truck wires connected, but the left didn't. I put some alligator clips between the two points and ran it a bit, smooth as silk, no jerkiness at all.  So i soldered a jumper between the two points and it runs just like spookshow said his did, fantastic.

I just wanted to share the experience for what is a nice loco, but maybe others out there have what could be considered a lemon.

Thanks,
Kent