I think I already know the answer to this question, but figured it wouldn't hurt to ask. We have an Athearn that fried it's 3rd decoder since Christmas last night. This time, it lasted about a month before it bit the dust. I re-worked all of the electrical connections when I reinstalled it (so I know they were good). I think the motor in the unit is simply pulling too much current for the decoder and that's what's causing them to go bad. I know they're gone the loco starts to short the layout. I pull the doecoder out of the locomotive and the short stops. We're using Digitrax DH126 series decoders in the model. Thanks in advance.
The problem could be intermittant shorts between the motor and the frame. In the DC set up the bottom brush of the motor got its power from the frame. For a DCC set up the bottom brush needs to have a wire attached and TOTALLY insolated from the frame. It could be the insolation is iffy and if the motor shifts slightly it is shorting out the decoder.
Best thing to do with these is to swp the motor clips - but be careful removing them since they hold the whole motor together as well as contain the brushes and brush springs. The one with the extra prong sticking out on the bottom is used to make contact with the loco chassis, if you put that one on top, or at the least, clip off the extra prong, you make it much less likely to get contact with the frame, which will instantly fry a decoder.
In addition, you need to insulate the bottom of the motor well. Don't use electrical tape, get some Kapton tape. It's much more resistent to abrasion so it won't wear through. Kapton tape is highly desirable for decoder installs. No, it's not cheap, but it's not THAT expensive. Not compared to 3 fried decoders.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
RR_MelRR_Mel wrote the following post 3 minutes ago: I cut out a piece of .01” thick scrap sheet Styrene and drop it in the bottom of the motor well for insulation. Mel
I also use the same method as Mel, but with ABS plastic sheet and I don't cut off the tab. I put the brass plate on a piece of flat steel bar and with a nail set, I hit the tab back into place where it was punched out, then file the area flush. I also insulate the trucks from the frame by cutting off the steel plate where the bolster rests and replace the steel plate section with a fibre washer so it sits at the same height.......but I run DC...I do it because I don't want a hot frame and it produces better truck pick-up overall, helpful for constant lighting circuits with LED's.
Good Luck!
Frank
RR_MelLocked rotor the BB motor can draw over 1¼ amps.
Thanks for the reply Mel.
I should have added, that one of the decoders got nuked because of this. A small peice of decoder wire that I had trimmed down became wedged in and bound the gears. I thought I had the problem sovled (ie, I thought this WAS the problem) after I removed it. For the diagram above, I assume the circut is across the orange and grey decoder wires to the motor? Is that correct? How do you wire them on your installs? soldered together in a peice of shrink wrap??
And to everyone else, I think the motor is fairly well isolated. But since it's easy enough to pull the motor out, I'll do that and double check it. And yes, I do need to get some kapton tape.
I've got 1 spare decoder left, I'm not sure I'm brave enough to drop it in yet. :)
Thanks again for all the replies.
As someone who told a person that they'd been throwing away good lightbulbs for years, I recommend NOT throwing away "burned out" or "shorted" decoders unless you see the nasty looking spot on the decoder.
Myself, I'd store it away with a piece of orange tape on it--my color for POSSIBLY defective. Or maybe in a marked envelope or baggy.
Or.
One could just throw it away.
Ed
I was surprised a couple of years ago to buy a "DCC Ready" Athearn engine and find out the engine hadn't been insulated from the frame. They added the lightboard with a DCC receptacle etc. but hadn't insulated it. Once I took it apart and took care of that, it worked fine.
Lonnie Utah RR_Mel Locked rotor the BB motor can draw over 1¼ amps. Thanks for the reply Mel. I should have added, that one of the decoders got nuked because of this. A small peice of decoder wire that I had trimmed down became wedged in and bound the gears. I thought I had the problem sovled (ie, I thought this WAS the problem) after I removed it. For the diagram above, I assume the circut is across the orange and grey decoder wires to the motor? Is that correct? How do you wire them on your installs? soldered together in a peice of shrink wrap?? And to everyone else, I think the motor is fairly well isolated. But since it's easy enough to pull the motor out, I'll do that and double check it. And yes, I do need to get some kapton tape. I've got 1 spare decoder left, I'm not sure I'm brave enough to drop it in yet. :) Thanks again for all the replies.
RR_Mel Locked rotor the BB motor can draw over 1¼ amps.
Mechanical binding some where??
Kapton tape not a real budget breaker:
https://www.amazon.com/BCP-Kapton-Polyimide-Silicone-Adhesive/dp/B00W3FAFP0/ref=sr_1_3?ie=UTF8&qid=1506048744&sr=8-3&keywords=kapton+tape
SouthPennMechanical binding some where??
There was, but I found the problem and I fixed it. The funny thing was, it had been running really well after that.