DCC Conversion of 1980’s Mantua Pacific - Shorts out system when put on tracks.

[gdelmoro]

System Components:  NCE Pro wireless system, DCC Spealties PSX4 Circuit breakers,  Digitrax SDH166D 1 Amp 8-Bit Sound Decoder 6 Function.

Motor isolated from Chasis and Brushes isolated from motor shell and chasis. Confirmed via continuity meter.

Electrical: Loco Chasis connected to Engineers side drive wheels and decoder (RED) wire soldered to chasis.  Tender chasis connected to Fireman's side wheels and (BLACK) wire soldered to tender chasis.

Motor (+) Connected to (GREY) decoder wire and (-) connected to (ORANGE) wire.  There are no other connections save the speaker factory wired into the decoder.

The decoder was bench tested and tested fine for all functions and motor operation before installation.

I don't see anything wrong but the loco trips the breaker as soon as I put it on the tracks.

Any Ideas? 

[CSX Robert]

Are you sure you didn't get a tender truck or axle turned around?

[NVSRR]

Or is the drawbar between loco and tender not metal or closing the gap?  Could one of the drivers be reversed or old insulation point be worn out?

shane

[gdelmoro]

CSX Robert

Are you sure you didn't get a tender truck or axle turned around?

 

YES the tender silver (metal) wheels are on the opposite side from the Engineer and the other side of both tender trucks are plastic and have no continuity between them and the tender frame. 

[gdelmoro]

NVSRR

Or is the drawbar between loco and tender not metal or closing the gap?  Could one of the drivers be reversed or old insulation point be worn out?

shane

 

there is in fact a metal draw bar connecting the tender to the loco.

[wjstix]

gdelmoro

NVSRR

Or is the drawbar between loco and tender not metal or closing the gap?  Could one of the drivers be reversed or old insulation point be worn out?

shane

  

there is in fact a metal draw bar connecting the tender to the loco.

 

 

The engine chassis is connected to one rail (+) and the tender chassis connects to the other rail (-). If you have a metal drawbar connecting them, it's a short circuit, right? Try removing the drawbar and see what happens.

 

I think all the Tyco/Mantua engines I've had going back to 1971 had plastic drawbars.

[gdelmoro]

Thank you for the replies.

I removed the drawbar and was able to get horn, whistle and a chuff that corresponds to my moving the speed up and down but no movement. 

Here are some photos

https://imgur.com/gallery/n5k3Crn\

Note that in one of the photos with the drawbar removed there would STILL be continuity between the right and left rails. ??? Meter is connected to the tender wheel (Left Rail) and the Loco Chasis (Right Rail). Still a short?

[wjstix]

It sounds like the metal drawbar was the problem re the short.

As far as not moving, it could be a wire isn't connected properly to the motor so it's not getting power. Note too that if this is an open-frame motor (Mantua switched to Sagami can motors around 1989) it may take a lot more power to get it moving than you may expect. Try putting it up to full power and, if still not moving, nudge it down the track a little. (Better yet, if you don't have the engine body attached, and it is an open frame motor, try turning the motor with your finger.) Some of those old engine motors seemed to not want to start moving sometimes.

p.s. engines with the old-style electrical pickup (tender wheels on one side only, engine wheels the other side only) are great candidates for a decoder with some type of 'keep alive', since they're not going to be picking up power as well as an engine with all-wheel pickup.

[woodone]

From your photos I see a red wire soldered to the draw bar terminal. at the draw bar post.

that would make a short- the red wire needs to attach to the frame, then to the decoder- the black wire from the decoder needs to go to the left side tender wheels-no need for the draw bar to be a connection has it is unreliable. NOTE  I see that you have your motor wires reversed.

Orange is the + motor terminal the Gray is the - terminal- if I am seeing the photos correctly.

 

[gdelmoro]

Woodone, the red wire is soldered to a screw which is in a drilled and tapped hole into your chasis. It is above te draw bar but not in line with the drawbar screw hole underneath. Is that ok?  The black wire is soldered to a drilled and tapped screw into the tender chasis. Note that there is only continuity between engineer side wheels and the loco chasis. There is no continuity between the Fireman's side wheels and the chasis or engineer side wheels. Same with the tender tree ic only connectivity between the Fireman's side wheels and the tender chasis. Is that not ok?

Thanks also for the motor wire catch. Still shouldn't it work but in reverse?

thank you

[gdelmoro]

Stix, thanks for the reply. The layout is DCCso there is always 14,? Volts DCC on the track (full power) as I understand it. The gray and orange wires were reversed and resoldered.  

Assume that in any case if we get this thing going I'll need to get a plastic drawbar. 

Thank you

[gdelmoro]

This is an exploded view, maybe it will help  

https://imgur.com/gallery/QqD51YU?s=sms

[gdelmoro]

Hi all, i disconnected the decoder to see if the motor was still running smooth. It hummed but would not turn until i got to full 12v.  Guess my next step now is to try and find a new motor with a gear to mesh with the drive gear. 

[rrebell]

You can put new mags on your old motor too.

[doctorwayne]

rrebell

You can put new mags on your old motor too.

 

 

rrebell is correct:  installing rare earth magnets in place of the original will make a significant improvement in performance.
Stack the magnets so that they fill the full height of the original magnet.  If the stack is just a bit short, with no room for another magnet, simply add a piece of steel thick enough to fill the gap.

 

Wayne

[dennis461]

I may have a Mantua motor hanging around. They are not very good compared to a can replacement.

As I see it, the Mantua ran on18VDC, while DCC puts out 12-15VDC to motor.