PS3 Forward Proto Coupler:

Upgraded to proto 3 from what?  PS1 proto couplers are different from PS2 and PS3 proto couplers.

What the heck do you need an opening coupler for on a subway set

PS2 and PS3 couplers are the same.  PS1 couplers operate at a higher voltage.

Be carful operating PS3 diesel/electric boards with only one coupler and no load resister on the other.  It will blow the FET on the board.  The diesel board requires two coupler loads to operate properly.  It will fire a single coupler a few times, then blow the FET if another coupler or a load is not connected to the board.  The PS3/2 stacker board shouldn’t need both loads.

@Ron045 posted:

Upgraded to proto 3 from what?  PS1 proto couplers are different from PS2 and PS3 proto couplers.

Upgraded from PS2

@bluelinec4 posted:

What the heck do you need an opening coupler for on a subway set

I actually want to move the coupler to the rear of the engines.

@Jon G posted:

Be carful operating PS3 diesel/electric boards with only one coupler and no load resister on the other.  It will blow the FET on the board.  The diesel board requires two coupler loads to operate properly.  It will fire a single coupler a few times, then blow the FET if another coupler or a load is not connected to the board.  The PS3/2 stacker board shouldn’t need both loads.

does this go for the board that would be used in a NYC subway engine?

The PS3 subways use the diesel PS3 board, so they need two coupler loads.  If it was upgraded from PS2 using a PS3/2 board, they can have one coupler load since this kit is also used in steam upgrades that typically only have a rear coupler.

The new AA, ABA diesels sold individually come with two proto couplers, but include a short dummy coupler to allow close coupling, but also include a dummy load to replace the removed rear coupler.

@Jon G posted:

but also include a dummy load to replace the removed rear coupler.

Can that dummy load be gotten without the kit, or make a substitute

@MCD4x4 posted:

Can that dummy load be gotten without the kit, or make a substitute

https://www.mthpartsandsales.com

Obviously could be DIY'd given you had the standard connector and resistor.

https://ogrforum.com/...er-resistor-question

@Bryant Dunivan 111417 posted:

thanks for help on another thread regarding upgrade files.  I learned to re-read the instructions 6 times.  I found that the rear coupler must be hooked up or a 4.7k-ohm resistor must be used if a coupler is not attached.  I intend to use the rear coupler on the trailing B unit.  My concern is the inadvertent operation of the powered A unit detached from the trailing B & A unit would fry the PS3 board because nothing would be attached to the trailing coupler lead from the board.  1 answer is obvious, “ don’t run without anything attached to trailing coupler”.  Is this the only solution or are there alternatives to allow single and multiple engine operation on the fly?

From this topic the connector type https://ogrforum.com/...mth-2-pin-connectors

@gunrunnerjohn posted:

They're not JST connectors, they're Molex Mini-SPOX 5264 Connectors, pins are at the bottom of the page.

Also called

@Engineer-Joe posted:

search for sbc-2 connector at All electronics for them.

Just use a burned out light harness and a 4.7k, 1/8 or 1/4 watt resistor. Cheaper than buying one from MTH.

My understand is the PS-32 also need it.  But running a rear coupler alone is ok.  What you can't do is run a front coupler alone.  Like F-3 diesel A unit.  If you have a unit with only a front coupler you must add the resistive load to the rear coupler plug.  G

Just checked with MTH.  The PS3 diesel board and the PS3/2 stacker board can run a single rear coupler, but if a front coupler is used either a rear coupler or dummy resistor must be installed.

@Jon G posted:

Just checked with MTH.  The PS3 diesel board and the PS3/2 stacker board can run a single rear coupler, but if a front coupler is used either a rear coupler or dummy resistor must be installed.

I wonder what design oddity made that necessary?

No idea.  Smoke and mirrors from the designers on the left coast.

@gunrunnerjohn posted:

I wonder what design oddity made that necessary?

John,

The Subways come with one coupler in the front only. Can the wire to the "front" coupler on the board be moved to the "rear" coupler pin on the board?

I suppose it could, though I'd just put the previously mentioned 4.7K resistor across the rear coupler connection.  However, if they come from the factory with only a front coupler, one has to assume that provision should have already been made in the wiring.

@Jon G posted:

Just checked with MTH.  The PS3 diesel board and the PS3/2 stacker board can run a single rear coupler, but if a front coupler is used either a rear coupler or dummy resistor must be installed.

Isn't that exactly what I said  G

@GGG posted:

Isn't that exactly what I said  G

Don hated to admit that you are right…