After the Plunge...

[ljudice]

Ok, dragged out the old DC power pack - and...

The loco seems to have intermittant contact through one of the brass "saddles" which come down from the circuit board
to make contact with the motor.

Any ideas??  Can it be bent into place?

Forget that---  On the fireman's side there is a tiny brass tab sticking out from under the motor!   It is attached to something and
is loose.  WTF?

[C855B]

Yes, shouldn't be an issue to fix. Just make sure it doesn't contact the frame. For that matter, check both sides closely - a short from a motor contact to frame could easily be behind your decoder problem.

EDIT: Hmm - check one of your known "good" ones to compare that loose tab. I'm not picturing it at the moment.

[ljudice]

See my update above....

[C855B]

Yeah, that is weird. There should be nothing between the motor and frame - it should all go to the board.

[ljudice]

Yes, shouldn't be an issue to fix. Just make sure it doesn't contact the frame. For that matter, check both sides closely - a short from a motor contact to frame could easily be behind your decoder problem.

EDIT: Hmm - check one of your known "good" ones to compare that loose tab. I'm not picturing it at the moment.

Nothing even like it on the others.......   Will post photo...

[ljudice]

[soo]

That is what is called the motor contact in layman's terms.

Wyatt

[C855B]

Interesting. It isn't making contact with either of the brush terminals, is it? By its position it appears to be putting upward spring pressure on the motor frame.

It certainly is suspect, however. Just need to make sure it's not making contact with anything in the circuit. Could also explain the difference running with the body off, since the body would put pressure down on it for positive contact with the frame.

The motor contact should be the "flag" on each side extending down from the board, with spring pressure against the brush cap. This little tab thing at the bottom is something I don't immediately recognize, but I don't have that model of loco.

[Bendtracker1]

Yes, and it needs to be straightened out and tucked in behind the tab of the chip.  You didn't see it on the others as they are in behind the large tab already.
While you're at it, be sure to remove the cat hair so it doesn't get caught up in the motor.

[ljudice]

Right, I know about the motor contact, it's the tab thing sticking out that makes no sense.

It is loose - connected to something under the motor but not firmly attached.

[ljudice]

Yes, and it needs to be straightened out and tucked in behind the tab of the chip.  You didn't see it on the others as they are in behind the large tab already.
While you're at it, be sure to remove the cat hair so it doesn't get caught up in the motor.

   This is a cat free zone!!!

Thanks will give it a try....

[ljudice]

That did it!    Working like a charm now...

Thanks everyone!!!!

[peteski]

No motor contact should be touching the frame (if the frame is used for electrical pickup) in a DCC-controlled loco.   What you had was not supposed to be there.  I think you should make FVM aware of this problem with quality control. A link to this thread would be a good way to do this. I think that this also explains why the loco acted differently with the body on.  The body probably pushed that strip to contact the metal frame.

[Bendtracker1]

  I think you should make FVM aware of this problem with quality control.

Pete,
I don't think I'd be too quick to call FVM on the carpet over this.
Since he is new to DCC, it might have been the case that he didn't get the motor contact strip tucked back in behind the chip tab and when he replaced the shell, it mashed the contact onto the frame.  Just look at the way it's bent, kind of matches the frame.

[peteski]

Pete,
I don't think I'd be too quick to call FVM on the carpet over this.
Since he is new to DCC, it might have been the case that he didn't get the motor contact strip tucked back in behind the chip tab and when he replaced the shell, it mashed the contact onto the frame.  Just look at the way it's bent, kind of matches the frame.

If Lou took off and reinstalled the factory circuit board then you are probably right.  Lou might have missed that the springy metal motor contact needs to be tucked under the metal "tongue" coming down from the circuit board. But if Lou never removed the circuit board then it is FVM's fault.

This could also explain the strange behavior. The top motor contact was attached to the decoder's motor output while the bottom one was connected to one of the rail pickups (DCC square-wave signal). That would explain that the motor was working but very slowly. Also, the decoder survived because there were no shorts anywhere.