Oh and Ken - if you don;t already have one, get a DC power pack. A full working MRC Tech II series can be had on ebay for cheap. If you don't have a multimeter with anythign more than milliamp capability, get one - even the $5 one I got from Harbor Freight has a 10 amp range (fat chance I'd put 10 amps through it at the listed maximum voltage - 750V! But at 12V it will probably take it). It's not super accurate on those ranges but it doesn;t have to be. Test unknown locos on DC before you even try to put a decoder in. The meter goes in line with one of the track power connections, use s small piece f track as a test track. Hold the wheels or motor shaft so it can;t turn and crank the throttle up - unless it's a completely crappy (like old train set) loco, doing this for a few seconds just to see what the meter reads is not going to melt it. Check the amps. Then get a decoder that meets or exceeds that stall current - say it reads 1.5 amps, a decoder with a 2 amp stall current rating will be safe to use - it won;t fry no matter how many cars you load up behind the loco, at least not from overloading. That doesn't mean you couldn't still fry one from a wiring error, but at least in anything approaching normal operation it won't.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Sounds like the motor was bad - shorted winding probably, perhaps from the previous owner leaving it stalled too long or leaving it sitting on DCC track without a decoder. It's not completely open, or the motor would not self-start if it stopped on that winding, instead somewhere deep within the insualtion melted off the magnet wire and shorted, making one coil say 20 ohms whereas the intact ones are say 100 ohms (just made up numbers - put a meter on it to see the real numbers - trying each combination you will probably quickly find the trouble). 20% power is probably just the minimal start voltage the Athearn motor requires - when you get that Dynamis system you'll be able to program the decoder so it starts at speed step 1 instead of 15-20.
cudaken I know that for what ever reason I am over loading the decoder, gets hot and melts. On the Dash 9, it was worked hard and pull sometimes up to 40 cars. I did add weights to, but could still spin the wheels. SD 50 on the other hand never pulled more than 15 cars, never had the power to do it. On the other hand I have a current style RTR SD 50 that is pulling 30 cars with the same decoder as the other SD 50. I am sure there is something mechanical wrong with the SD 50, rather it be a bad motor or problems in the trucks. I will take it and the Dash 9 to LHS this week with the DC chip's installed and see what kind of amp's power they pull on a MRC 9500.
I know that for what ever reason I am over loading the decoder, gets hot and melts. On the Dash 9, it was worked hard and pull sometimes up to 40 cars. I did add weights to, but could still spin the wheels. SD 50 on the other hand never pulled more than 15 cars, never had the power to do it. On the other hand I have a current style RTR SD 50 that is pulling 30 cars with the same decoder as the other SD 50.
I am sure there is something mechanical wrong with the SD 50, rather it be a bad motor or problems in the trucks. I will take it and the Dash 9 to LHS this week with the DC chip's installed and see what kind of amp's power they pull on a MRC 9500.
Little up date, on the SD 50 I installed a different motor today and all so found the board was a Digitrax, it is nothing like my other Athearn RTR boards. Installed a new board and a DH 163 deoder. It now starts moving at 20% power where before it took 50 percent.
Making some head way.
Cuda Ken
I hate Rust
ARTHILLI connected DC leads to the output side of the decoder. That warmed it up.
Art might be on to something. Grab a magnifier and make sure there are no stray wires crossing contact pads/pins from the DCC feeders to the DC motor output on the decoder. Even the tiniest wire could cause problems. I once had a ~64 gauge wire crossing terminals on a 1.5V DPDT switch. It was enough to throw the whole thing off and overheat it.
Other possibilities:
1) Running wrong voltage to track for your scale. For HO scale, you should be running about 15V->16V
2) Decoder is not properly heat sinked. If you just let your decoder "float" freely inside your train, it might not be able to loose the heat. I like to bind mine to the body shell or frame with Bathroom caulk. You would be surprised the amount of heat that is transferred to the shell/frame from the decoder.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
I connected DC leads to the output side of the decoder. That warmed it up.
If wires are melting, and the system is shutting down, my first guess would be a short. Also my second and third guess.
Well the answer is me owning it a course
I have had 3 decoder melt in the last year. First one was in a Blue Line GE AC 6000, I forget which one it was and it was a N Scale decoder. It was replaced by LHS a year ago and has lived for a year now.
Today I took to RIP (remain in places) engine to work to see what was wrong with them. Both are Athearn RTR engines.
1 Athearn Dash 9 had a DH163PS installed. This had been a great running engine and saw a lot of time. I guess it was this spring when it had it first problem. While pulling a modest train of around 20 cars and in a tunnel it stalled and melted the wires from the truck's to the PC board. Replaced the PC board, installed heaver wire. Decoder looked a little toasted cover was melted a little but worked fine. It finally gave up the ghost after another 50 hours of run time. When engine was on the track it would shut down the DCC system. Today I installed the DC chip and it seems fine.
2 Athearn SD 50 a problem child from E-Bay from the get go. It is a older RTR, looks a lot like a Blue Box when taken a part. Still has the metal arms on the trucks. Each truck has a wire solder to it and goes to the PC board. Other power side of PC board only has one wire that is in the front and is grounded by a screw to the chassis. It has all wise taken a lot of throttle to get the engine just to move, say 25%. Get to a decent speed 80%. I have all so posted about this engine in the last two weeks, it is the one that eats light bulbs.
Today all I was going to do is install new lights and lube it good. Sat it on the test track and it would hardly move, took 100 throttle to do 30 sMPH. Decoder is DH123PS and cover looked a little melted but not burnt like the one in the Dash 9 above. Installed the DC chip and it ran a little faster but still not well. Installed the decoder chip again and started to clean the arm with a easer. Motor stalled, then DCC system shut down! Installed the DC chip and it ran but still poorly.
I am sure there is something mechanical wrong with the SD 50, rather it be a bad motor or problems in the trucks. I will take it and the Dash 9 to LHS this week with the DC chip's installed and see what kinf of amp's power they pull on a MRC 9500.
Thank You for the up coming answers.