I have a wonderful older Bessemer SD 7 by Proto 2000 none sound. It is a older engine and was a gift. Runs great and it quite! One day it ate a decoder on power up. It was sitting on a turnout (unpowred) when it ate the Digitrax 121 decoder.
Pulled the BBQ decoder and installed a DC chip. Engine free wheeled at .35 amps and stalled at .85 amps? I heard the Digitrax 121's where pretty much junk so that must be it!
Tested the motor again a few weeks later and got the same numbers so motor must be good! Installed a DH123 and had been for 2 weeks. Last night I happened to fire it up sitting on diffrenet turnout, it's dead.
Have not done any testing yet, but if the motor is again fine what should I look for? Think the gauge of the wheels are good, does not pick any turnouts under power and never derails?
Looking for ideas if motor is good and will test after I am done BBQing food, not decoders!
Cuda Ken
I hate Rust
Ken,
You tested the SD7 for stall current. Have you determined if the motor brushes are truly isolated from the frame?
The older Proto Alco S1/S2 switchers were said to be "DCC-ready" but they were not and the bottom motor mount was shorted to the chassis. Since the decoders are giving up the smoke at turnouts says to me that the frame is somehow touching and shorting to another rail.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
Is the factory board still in the loco? The SD7 had the kind of board that needed traces cut for DCC, then you could connect a decoder to the 8 pins. If one of those traces is not totally cut through it could intermittently make contact.
The one of those I put a decoder in, I just removed the factory board and hard wired it all.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Randy and Tom thanks for the answers! I had missed placed the DC plug and just found it late last night. Hope to test the motor tonight.
Orginal board was replaced and decoder install was done my Pullman. Will check the motor install after I test the amp's it pulls.
Thanks again for your time.
Ken