Decoder running hot

[djp]

Hi there, My 2-8-0 decoder gets hot enough to feel through the tender body after about 5 minutes of running. Speed control is really poor. Loco starts moving only after half throttle on the Bachmann EZ Command. Keeps speeding and slowing down irregularly. Wheels are clean, track is clean and other locos don't behave like this. Loco motor is not hot as i cannot feel any heat through the body of the loco. Any help would be appreciated.

[Jim Banner]

What decoder do you have in your 2-8-0 locomotive?  If it is anything other than a Bachmann decoder, did you remove the capacitors when you installed it?  The capacitors cause silent decoders to run hot and control to be erratic.

[djp]

The decoder is the factory installed one. For the first few days it worked ok then it started behaving funny. I have not cut any capacitors as i have not found any there [i believe they are yellow in colour right?]. All i see are two coils or something on the pcb along with the other stuff [sorry not very well versed with the electronics lingo]. Would it be better if i just bypassed the whole pcb and soldered the wires directly to the motor, pickups and lights? If you need i can send you a picture of the pcb. Thanks.

[r.cprmier]

Would it be better if i just bypassed the whole pcb and soldered the wires directly to the motor, pickups and lights? If you need i can send you a picture of the pcb. Thanks

I have advocated this method for about a year or so.  Direct wiring eliminates the potential for problems due to this whole adapter block thing.
You can download any information to make you comfortable doing this from various mfgrs, such as Soundtraxx, NCE, etc.  Just pay attention to what you are doing, make good solder joints, and heat shrink your work-after you check your work!  Get a decent multimeter, available at most electrical or electronic supply houses, or Radio Shack.  I have a Simpson I have had for about thirty five years, and it is still trusty and able; but other good ones are available for decent price, commensurate with quality.

The Old Reprobate

[djp]

I have installed a decoder in a 2-10-2 which i got with my President's Choice set and one in my old GP 40. They work fine. The rest of my locomotives are DCC straight from the factory. Any idea why they have put PCB's in the loco's if just simple hard wiring does the job?

[Jim Banner]

Any idea why they have put PCB's in the loco's if just simple hard wiring does the job?

Not everybody is comfortable with soldering.  From some of the installations I have reworked, some people shouldn't be allowed anywhere near a soldering iron.  But for those of us who can solder and can follow simple step-by-step directions, hard wiring is the  best solution.

Having said that, in your particular case I would hesitate to hard wire the factory installed decoder.  The fact that it worked fine for a few days before going funny indicates that the initial installation was okay.  And chances are, it is still okay.  That leaves a faulty decoder as the most likely source of your problem.  If it is under warranty (which usually means you purchased it from a Bachmann dealer) then Bachmann will usually replace it.  But if you hard wire it in place, they normally will not cover it under warranty.

If your locomotive is NOT under warranty, then by all means try hard wiring the factory decoder.  But make all the measurements along the way - motor stall current at 12 volts, continuity from pickup wheels to decoder, and open circuit between all wheels and both motor connections.  As r.cprmier suggests, a good volt-ohm-millamp meter will be a big help in the measurements but then again so will a low cost analogue or digital meter.  The one I use the most cost less than 10 bucks.  Then if the decoder still over heats, it has to be the decoder that is at fault.  Installing a new decoder of your choice should then solve your problem.

ADDED THOUGHT:
Is your 2-8-0 equipped with a sound decoder?  If so, they normally run hotter than a motor only decoder.

[djp]

No, it is not under warranty. I guess it looks like a faulty decoder. It is a regular motor decoder. No sound. It gets as hot as a coffee cup. That is, you cannot hold it for more than a few seconds. I guess that is not normal right?

[Jim Banner]

That is not normal.  Warm is okay but too hot to touch isn't.

[djp]

 I'll try just bypassing the pcb. If the loco still acts up then a new decoder will be in line. Thanks for the help.

[Hunt]

Check the best you can for binding in the drive mechanism and other moving parts. Maybe there is not enough binding to stop the locomotive but enough the motor is drawing power just below the decoder’s shutdown. Check the Amp draw if you have the meter to do it.