Athearn SD38-2 Odd Running Problem

[Anonymous]

Just picked up an Athearn bluebox SD38-2 from a guy on eBay. Has a decoder installed in it and the guy installed ditch lights, but set one of the lamps to fn2, which on my zephyr is a momentary contact function, not latching. I think I can change that... but that's not my question/problem for this topic... Sorry to run off on a tangent like that.

The loco, if run "forward", will derail in a couple of spots on my layout where my radii get a wee bit tighter than 18", like 17.5" or so... Yes, I have much improvement to make in my track laying skills... Anyway, if I take the same loco and physically turn it around and run it in reverse, it won't derail.

Any ideas why this is the way it is?

[randyaj]

Pete,
Check the wires inside the carbody. If the wires are a little big or they are too tight to the lead truck, or if they are bunched up in such a way that is binding the truck from turning in one direction it may cause the engine to derail.
Randy Johnson
Iowa

[SSW9389]

Athearn doesn't make an SD38-2. The only ones I know of are either brass or KATO. Maybe it's an Athearn frame with an RPP SD38 shell on it? ? ? Whatever randyaj has most likely hit on your problem. You have to use small flexible wire or the trucks will not operate properly.

[rrinker]

Also check the wheels for a bent one, or a missing chunk out of a flange. On two different brand new units (nearly 20 years old, but never run before) I've seen this. The bent wheel one wobbled noticeably - on checking the wheels, it was apparent that the wheel in question didn't seat properly in the press that pushes it onto the stub axle, and the machine just rammed it on. The one with a chunk missing from the flange, dunno how that happened, maybe incomplete mold fillup. It didn't derail but it thumped over turnouts. I caught the chunk missing when I checked for proper wheel gauge.

--Randy

[Anonymous]

Thanks everyone. I'll check it out tonight or tomorrow and report back my results.

[Anonymous]

OK. Everything is running good now.

Main problem - derailing - found that the front truck wasn't turning far enough. There was a pretty stiff wire that the guy who installed the decoder ran from the front truck pickup to the back truck. I removed that wire, but it was still derailing. Did a little modification to the frame with the old dremel tool, now the thing turns like a champ.

Second problem - ditch lights each on a sep. function - wired both lamps to fn1... Need to change resistor as lamps are a little dull now, but at least now they both come on at the same time and stay on...

[rrinker]

What kind of decoder is it? I would probably put the wiring back so that each ditch light has it's own function - that way you can make them alternately flash. Didn't check your location, if you're in Canada then no flash is fine [:D] The mapping kind of make sense because you can program the decoder so that hitting F2 for the horn starts the ditch lights flash, which is typical US practice.

--Randy

[Anonymous]

Randy - Thanks for the tip on the decoder/ditch lights. Didn't know they were supposed to flash (dummy me)... It's a digitrax 163 decoder, so I should be able to figure out how to make all that work the right way.

[rrinker]

QUOTE: Originally posted by petejung

Randy - Thanks for the tip on the decoder/ditch lights. Didn't know they were supposed to flash (dummy me)... It's a digitrax 163 decoder, so I should be able to figure out how to make all that work the right way.

Well they don't HAVE to flash, that's US practice. I was just pointing out that if you WANT them to flash, you need each bulb on a different function. The setup you need is given as an example inthe Digitrax decoder manual (if you don't have one, get the PDF from the Digitrax site.)

--Randy

[Anonymous]

Thanks Randy. I'm one of those guys that if he doesn't know any better, he's happy... But now that I am aware that they are supposed to flash, it will haunt me until I fix my error. Plus, it will be good practice to re-wire it and I suppose potentially need to reprogram some CV's. I've never done any programming to a decoder except the loco address. 'Bout time I expand my horizons a little :)

[rrinker]

Check out RR-CirKits and order a Locobuffer. Then go check out the JMRI web site http://jmri.sourceforge.net and download the FREE software. For this you are interested in the DecoderPro component. On some mostly plain English screens you can select how you want the lights to work and it will handle the programming.
I don't have any problem converting the hex numbers and so forth, and I STILL use DecoderPro. It's simply better, faster, and easier than using the throttle or Zephyr console to program.

--Randy