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I recently scored this nice little MTH Premier switcher, and on it's first run out, it stalled on a pair of switches in a staging yard.  Bummer, that's what switchers are for!  So, I took a look and of course, the reason is obvious, no rollers on the locomotive, only a pair on the tender.  There were some holes in the frame for the standard MTH roller hardware, so it seemed like it would be an easy upgrade.

WAIT, they used the roller pickup wire in the tether for the front coupler!  Bummer, no way to get the power back to the electronics in the tender.  Not to be deterred, I fell back to my normal fix for Lionel IR tether locomotives, a separate tether wire.  So here it is in pictures.

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First step, mount the MTH roller, the BD-0000042 is the shortest one they have, and it just fits.  It was a bit tricky inside as they didn't intend to install rollers and mounted stuff above the mounting holes.  After removing some things, I was able to get a roller and wire installed.  I did have to grind down the inside roller insulator to get it into place.  The clearance is small in the roller well, and when the roller is fully depressed, it can contact the locomotive frame.  To protect against that, I stuck a piece of Kapton tape in there to insulate it.  The parts used were the BD-0000006 and the BD-0000009 roller pick-up insulators along with the BD-0000042 roller.  I don't happen to have the number of the hex post that secures these handy...

MTH Switcher Reliablity Upgrade N1

The red wire is from the roller pickup, it goes through a 1.8A trip PTC to protect the wire.  This is in case of a derailment or the tether pin getting shorted to something when not plugged in.  That shouldn't happen, but then things seem to happen when you least expect them to.

MTH Switcher Reliablity Upgrade N2

Here's the two tether pieces, I use machine socket parts to create the tether.  The tender end is tapped directly into the roller wire in the tender and routed down to mate with the locomotive wire.  I used a piece of clear heatshrink to secure the power wire to the "wireless" drawbar.

MTH Switcher Reliablity Upgrade N3

Here they are lashed up, it's hardly noticeable that something has been added.  Now it has no issue at all going over switches, job done!

MTH Switcher Reliablity Upgrade N4

Hope this helps someone in the same boat.  It's a nice little switcher, and now it can actually perform it's intended purpose.

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Hay John,

About the 1.8 amp PTC, is this a standard size for all small loco's that you install? I would guess that for a larger loco ( which probably doesn't need the extra set of roller(s) since it usually has 2 to 4 rollers under the engine), it would require a larger PTC amperage rating. Maybe you have never experienced this with a larger loco. If you have, what would be the size of the PTC value in this case. Could you supply the part number of one or both PTC's and the latter PTC's amperage rating. My guess is you got the PTC from Digikey. Thanks for sharing the experiance, it's great info!!!

 

George Mason posted:

Thanks for sharing. For fear of damaging things, I would not have the nerve to try that. Well done!

is it possible to switch an older DCS locomotive from the thick tether wire to the tetherless connector? 

George, it's not really practical to switch to the "wireless" drawbar, there are hardware mounts on both ends that have to be there to support it.

John J. Giuliano posted:

About the 1.8 amp PTC, is this a standard size for all small loco's that you install? I would guess that for a larger loco ( which probably doesn't need the extra set of roller(s) since it usually has 2 to 4 rollers under the engine), it would require a larger PTC amperage rating. Maybe you have never experienced this with a larger loco. If you have, what would be the size of the PTC value in this case. Could you supply the part number of one or both PTC's and the latter PTC's amperage rating. My guess is you got the PTC from Digikey. Thanks for sharing the experiance, it's great info!!!

I use from 1.3A to 1.8A for these.  I happened to be out of the 1.3A ones or I'd have used one here.  Truthfully, I doubt you'd ever need more than a 1.8A trip for any locomotive, remember these are only for momentary power loss, and it takes a lot more than the trip value to instantly trip a PTC.  I get the PTC parts from Digikey, you are correct.  Since it's a #22 wire to the tether, I figured I could "risk" a 1.8A trip part.

Any of these should be suitable: Digikey 1.3A Trip PTC List

A good choice that's cheap is the MF-RX065/72-0-ND, it should do nicely. 

Here's it's trip curves.  For a direct short, it should trip in less than .1 seconds with 10 amps of current.  With a partial short of 4 amps, it will trip in under 2 seconds.  With #22 wire, that is plenty fast.

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clem k posted:

I have the 2 rail version PS- 3  0-6-0. Had my dealer add the roller and tie all the ground wires together. Didn't need to run a extra wire because I have Kadee couplers on it, it operates in a 3 rail environment. Never stalls and smokes 100% better.

This had nothing to do with Kadee couplers for PS-3 steam.  The 6 pin wire harness for drawbar carries Track power between tender and engine.  So you can add pickups to either and tap into the AC Track power wires.  The engine boiler board runs all engine functions, and the tender board runs all tender functions.  So you can keep MTH couplers and still do what you want for PS-3 steam. 

There is no 5V Coupler wire on MTH trains???????  Couplers run off PV.

Now on a PS-2 engine with forward coupler and PS-2 board in tender, you can gain one wire back by removing coupler connection and repurposing the Forward Coupler trigger wire.  You could also do the headlight different and regain that wire.  G

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