Converting an analog DC N scale loc to DCC

[abe]

Hi,
I understand that a loc. motor wire contacts should not be connected anywhere to the chassis in DCC operations.
When I check my motor contacts with a meter I see that there is about 47Kilo ohm resistance between the contacts (brushes) and the shaft that goes through the motor. There is no way I can insulate the motor shaft from the brushes. The shaft is mounted inside the metal motor housing. So it is all metal on metal.
Can anybody help me.
I have a Minitrix 12860 loc and would love to make it run in DCC operations.
Thanks,
Abe
P.S. Does anybody know where I can have it done? I have a TCS Z2 decoder.

[rustyrails]

Abe, you might try posting this question on the N scale board here.  Here's one company that does custom decoder installations:

http://www.tonystrains.com/index.html

and there are plenty of others.  Also, if you search on "minitrix dcc" there are lots of articles.  Wish I could be more helpful, but I haven't had an N scale engine disassembled in about 20 years.

[Jim Banner]

abe, that high a resistance is most likely from carbon dust off the brushes as they wear (I assume the locomotive has some miles on it.  I also assume that you disconnected everything from the brush terminals before making this measurement.)

You may be able to blow the dust out (gently - do not used high pressure compressed air as it may damage the fine wires in the armature) or you can wash it out with contact cleaner (the non-lubricating kind.)  Personally, I wouldn't worry at such a small leakage.  At 48k, the leakage at 12 volts would be only 1/4 of a milliamp

Jim