MTH PS2 3V Diesel Tether Questions

there is no audio amp in the slave. You should change the lead's speaker to a higher ohm if you're adding another to that amp (or wire in series).

PS2 3 volt = 2 x 8 ohm speakers for example. You have to know the limit of the amp.

I believe the tether carries the tach info to the slave. There's a post about it from Dave Hikel in the past. I forget what it carries exactly.

Lead units run by themselves. Slaves need the lead unit for info.

@Lehigh74 posted:

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If the tethers don’t carry track power, what do they carry?  I’m somewhat challenged electronically, but I’m guessing they carry logic signals to operate the trailing unit headlight, smoke unit, speed control and coupler.

Correct. the tether carries only "logic" signals to control the trailing unit lights, smoke, motors, and coupler.  These low-current logic signals are amplified/buffered to high-current.  The high-current comes from the power pickup in the trailing unit.  The board in the trailing unit is referred to as a "slave board".

Is it possible (for someone that is electronically challenged) to add a speaker to the trailing A unit?  Each A unit has a board so I’m wondering if there is a connection on the trailing unit board to plug in a speaker for the trailing A unit.

The audio signal is not carried on the tether.  I suppose one could co-opt some of the logic signals (thereby giving up their functionality) and wire the audio from the lead unit to the slave board via the tether.  But in my opinion this would be an electronically challenging project with plenty of opportunities to mess things up.

What is the part number for the speaker?  The MTH site has a parts list, but it’s for a 5V board.  And it doesn’t give part numbers anyway.

Will the lead A unit run by itself?  I’m guessing it will, but the manual is silent on this and I don’t want to risk it.

The lead A can run by itself.  The trailing slave unit with disconnected tether should just sit there.

Thanks Joe and Stan.