Why Did MTH Produce Tethered Multi-Unit Diesels for so long?

Good questions, Rod.  I have a PS ABA set that I was going to upgrade to PS3 until I learned it took an upgrade kit in each A unit.  The tethers do make it hard to connect and put on the track.  It has sat on the shelf for many years with an occasional run.  A friend who runs conventional was interested in it, so I finally decided I would sell it to him.

Here is my impression on this- both as a repair person, and an owner of many of these, and experience from helping/seeing others use them in various situations.

#1 comes down to cost. The slave board in PS2 was relatively cheap compared to yet another full stack PS2 board set, encoder on the motor, battery (PS2 era).

#2 Added complication when running in conventional mode- which may have been a bigger requirement in that time era- people buying MTH PS2 engines, but not yet buying into DCS. The problem in an ABA set or just AA set, the trailing engine faces backwards. Modern PS3 -especially Premier- diesels intended for this scenario have a bunch of extra switches that can reverse the lights, reverse motor direction as a huge complication and cost to the wiring harness beyond the original board.

Again, this is just my perspective- a single processor or control board in the lead engine, connected to the trailing engine via tether- works both in DCS and conventional without a bunch of user interaction with switches. And arguably, it's less electronics and in theory, cost less to produce.

In PS3- they tried slave boards in very few engines- example turbotrain, but that is a unit train. I think either cost or complexity- maybe even reliability, they opted for just 2 complete PS3 diesels, but then that turned into the extra switches required for the conventional running scenario needed to reverse the lights and the motor direction on a trailing unit.

It's all a compromise in some way. Not trying to derail- but big L and these new LCP2 based AA diesels, the second unit being a listen only bluetooth is another example of compromise- you cannot split them up and run only the trailing engine under bluetooth by itself.

So yes, different companies and models have dealt with this different ways, and I completely understand the hate for tethers. I do know the pain. But I've also seen the alternative.

@Mark Boyce posted:

... The tethers do make it hard to connect and put on the track.  ...

This is the thing I dislike most.  And it creates another point of failure.

I also don't need two powered engines, so getting an A-A set is just too much expense.  It's made it a lot easier to resist buying more engines - I have plenty already.

@Mallard4468 posted:

This is the thing I dislike most.  And it creates another point of failure.

I also don't need two powered engines, so getting an A-A set is just too much expense.  It's made it a lot easier to resist buying more engines - I have plenty already.

I hear you; no one likes messing with those tethers. I tend to leave a tethered set on the layout for quite a while before removing it and running something else. It is what it is I guess.

A simpler route is RK sets where there is only the powered A and the other two are dummies. But you still have a tether to deal with. One option for a Premier set is to pull the motors and electronics in the trailing A and use it as a dummy. You could then wire the rear lighting to be on whenever there is track power and remove all the tethers and connectors. I imagine there are folks that have done that exact thing especially if the trailing unit slave  board fails.

Rod

@Vernon Barry posted:

Here is my impression on this- both as a repair person, and an owner of many of these, and experience from helping/seeing others use them in various situations.

#1 comes down to cost. The slave board in PS2 was relatively cheap compared to yet another full stack PS2 board set, encoder on the motor, battery (PS2 era).

[Rod]-If this were the case, why do slave kits cost 20 bucks more than the master kits?

#2 Added complication when running in conventional mode- which may have been a bigger requirement in that time era- people buying MTH PS2 engines, but not yet buying into DCS. The problem in an ABA set or just AA set, the trailing engine faces backwards. Modern PS3 -especially Premier- diesels intended for this scenario have a bunch of extra switches that can reverse the lights, reverse motor direction as a huge complication and cost to the wiring harness beyond the original board.

[Rod]-So why not use PS-2 boards in both A's and set the direction as backwards standard for the trailing A unit? This  would work fine for conventional. Then in command mode you could make a lashup and change the rear direction if you so wish.

As above Vernon; I don't buy the added cost angle of making both A units fully functional PS2 or PS-3 engines. Seems to me the savings from deleting the tethers would more than offset the board cost difference, even if there was a difference. But hey, that's just me. Thanks for your input!

Rod

I remember years ago when i first acquired some MTH AA or ABA units I wanted to create a post asking members how they connected the tethers on these diesel sets.  Did you do it the easy way and lay them on their side and connect the tethers out in the open before setting everything upright and trying to place the wheels on the track?  Or did you put them on the tracks first and try to work your fingers underneath to tether up that way.  Both methods had their drawbacks.  

Ultimately I never did ask the question for fear of looking like an idiot.    Now I see I wasn’t alone.  (For the record most of the time I laid them on their sides.)