Paul Daniels could not have done this!!

[electricity_bill]

Hello again
About eighteen months ago, I fitted an MRC decoder to an Aristocraft Alco A unit. It was connected to a matching B unit using a the A unit decoder (see G Scale Journal Spring 2011). It ran really well throughout last summer and I put it away for the winter. On getting it out this spring, I noticed that the current drawn had increased substantially and it did not seem very happy. I got round to looking at it today and split the A unit from the B unit. I was amazed to see that the A unit was hardly able to move alone and a quick check revealed that the bogies were driving in opposite directions!!!
A quick swap of the bogie direction saw them back in harmony and the current drawn was back to the previous level.
How can this happen?
Bill

 

[Gizzy]

I guess you didn't think much to that?

'Not a Lot'....

 

[Tim Brien]

Bill,
your choice of decoder. These are renowned for their inability to retain required CV settings.

 

[electricity_bill]

Reaul Daniels could not have done this!!

Yes but

one bogie reversed?

Are eye

Bill

 

[KeithT]

Reaul Daniels could not have done this!!

I blame Fred.

 

[ntpntpntp]

Reaul Daniels could not have done this!!

If there's only one decoder driving both bogies then I don't see how one bogie would somehow reverse direction compared to the other, unless it managed to swivel 180 degrees on the chassis or was removed for servicing and incorrectly refited / rewired. Swivelling round seems unlikely if the bogies have truck mounted couplings? Also you'd get a short if one bogie was swivelled without also swapping the pickup wiring over. For one bogie to run backward the motor wiring would need to be reversed without having reversed the pickup wiring.

If you haven't had it apart then very curious!!