MTH Switcher Reliability Upgrade

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? 

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.

Bravo John!  Should have had it in the first place.

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.

John,

One huge advantage for doing the 3RS, Kadee coupler thing is getting your power feed back on the little engines!  I put rollers on all of mine.

Before I started using Kadees, I did the same thing.

Dave

So you're saying you get the 5V wire back since you don't have a coupler using it?  Makes sense, but the added wire was no big deal and I still have the electrocouplers.  I like the look of the KD's but it would be a LOT of work to convert my fleet.

Can you advise the part number for the PTC. I went to digikey web, what I pulled up was special order.

 Thanks 

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.

gunrunnerjohn posted:

So you're saying you get the 5V wire back since you don't have a coupler using it?  Makes sense, but the added wire was no big deal and I still have the electrocouplers.  I like the look of the KD's but it would be a LOT of work to convert my fleet.

It is a commitment.

David Minarik posted:

gunrunnerjohn posted:

So you're saying you get the 5V wire back since you don't have a coupler using it?  Makes sense, but the added wire was no big deal and I still have the electrocouplers.  I like the look of the KD's but it would be a LOT of work to convert my fleet.

It is a commitment.

Or you should be committed.

Thanks 

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

GGG posted:

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

Correct.

Or just add a single wire like I did and keep all the existing controls.