Atlas Decoders

Model Railroader General Discussion (Model Railroader)
1

I have been collecting Atlas locos for years and am now getting into DCC, finally!

In going over my locos I am finding some where the box says “Dual Mode Decoder Equipped” (circa 2001) or more recently “4 Mode Decoder Equipped” etc etc.

Since I am naive to what all decoders are able to do I am wondering if these built-in decoders are fully functional or whether they need to be replaced with something like a full function Digitrax decoder etc.

Of primary importance to me are creating consists, adjusting speed control of each loco so speeds match in consists and perhaps lighting control (ie, front, rear, on/off etc).

Would appreciate any comebacks.

Thanks!!

2

They should be fully functional. Don’t know how many “features” they have but they should work.

-Smoke

3

The earlier Atlas dual mode decoders had a jumper 8-pin connector that had to be repositioned to switch from DCC to DC or visa versa. The newer Atlas decoders have a little switch that controls which system will work. Both kinds have the ability to control the power and directional lighting. They are NMRA compliant and accept consisting and other DCC functions just no sound.

The earlier dual mode decoders sometimes created some motor hum and for that reason some people replaced them. All of my Atlas loco’s still have their original decoders and they work fine.

4

Some of the newer Atlas decoders may have a switch, but the three GP38’s and two GP40’s I recently bought (shipped by Atlas in December '06) still have the 8-pin jumper to select analog or DCC Operation. They’re Atlas #342 Four-function Dual Mode decoders. Not sure why they require moving a jumper if they’re “dual-mode” decoders, but that’s a question for a different thread.

I’ve heard about that motor hum, but I’ve never experienced it.

Steve

5

I’ve got a couple of atlas 342 decoders (these use the jumpers on the 8-pin plug) I started using with early Gensis locos because they were a drop-in…sort of. I believe they will accept programing on the main but I still haven’t discovered how to adjust the top voltage on them, perhaps you have to enter a custom speed table. Generally though they work fine and I have not run into a motor hum problem.

Tilden

6

My Atlas SD24 has the newer decoder with the switch. I guess the GP38’s and GP40’s still have the 8 pin jumper as they originally had.

I have one GP38 that has a slight hum in the motor when sitting idle but it still runs great.

7

One of GP40s from the first run, has just started to develop a hum. I thought it was the motor itself since it has been run many, many hours. I’ll have to check the decoder first.

I noticed that the first dual modes had the very large capacitor, more recent 8 pin jumper ones have a much smaller one.

8

I have 6 Atlas decoders, all factory installed in GP38s and GP40s. Haven’t had any problems. The GPs have a big space where the hatch opens up to change the jumper around. Don’t have to remove the whole shell.

I would just use the decoders if they are factory installed. I tried programming them to automatically switch when on DC, but they don’t do it. The LEDs light up, but no movement. Move the jumper, they work fine. Bypasses the DCC circuitry, so they run like any Atlas on DC.