Question- Slave board installtion

That's a good question!

The master engine sends the following to the slave via the 10 pin harness:

Both motor leads, smoke heat return and fan motor return, Positive voltage, interior lights, rear light, rear coupler, PCB Ground (board ground not track AC ground), and MARS2.

Are you trying to use a slave board in the motorized slave unit?  If not, and you just want to power the motors from the lead unit, you will have a problem overloading the Master engine board with 4 motors on one board.

Operating the rear coupler from the lead engine can work, but it needs 2 wires.  PV and Rear coupler return.

Using the CV board for lighting is ok.

The only unknown if using a slave board, but only an existing 4 pin harness is whether the slave board needs the PCB and or PV to work properly.  All the other components that go to the slave are used to tell the slave what to do and keep it in sync with the Master board.  Why PV and PCB Gound are sent over is not know.  I would think the Slave generates it's own PV and PCB Ground but it doesn't have a full wave bridge like the Master board, so maybe not.  Give it a try and let us know.  The potential is that the electronic on the Slave board won't work with out PV and PCB Ground.  

As one last warning, don't try to power 4 motors from the Master board alone.   G

The only unknown if using a slave board, but only an existing 4 pin harness is whether the slave board needs the PCB and or PV to work properly.  All the other components that go to the slave are used to tell the slave what to do and keep it in sync with the Master board.  Why PV and PCB Gound are sent over is not know.  I would think the Slave generates it's own PV and PCB Ground but it doesn't have a full wave bridge like the Master board, so maybe not.  Give it a try and let us know.  The potential is that the electronic on the Slave board won't work with out PV and PCB Ground. 

That's what I've been wondering since this post was started..That is why the PV and PCB Ground are sent to the slave board? I have 2 kits here and have all the schematics but never really dove into how the master "talks" to the slave as never really had the time.

Thanks for the replys! I have discussed this with an MTH tech and did not receive an answer that was clear( to me). He did tell me that the slave unit had to have track power and to use the 7 pin connection on the end of the board. The kit contains a 7 pin harness that has 2-red wires and 2- black wires, I have conected them so they pick up track voltage. He did not mention a need for power coming from the main board. I will be testing this this weekend and I will post the out come. MTH's instruction on the use of the slave board is very WEAK! The option of using 2- upgrade kits, when you can. is the way to go in consideration of the quality of the Slave unit instructions. Any thoughts on the use of the slave board are appreciated.

Bill C.

but it doesn't have a full wave bridge like the Master board

It does as there's 4 big diodes mounted on the board.

After studying the schematics I think it should work just as you're doing it Bill but you can also tap the slave board for the rear coupler...or are you using the supplied wiring harnesses?

Which slave kit are you using..The II-0001903 or the 1905?

Thanks Chuck, I am using 1905 at this time, I do have a gas and coal turbine I am going to work with on later with 1903. I am using the existing 4 wire tether for the motor funtion and the uncoupler funtion. The E-8s that I am upgrading are a part of a passenger set and the operation of that set does not require an operating coupler. If needed I can give up the uncoupler funtion if I need 2 addtion tether wires. My goal was to use the existing 4 wire tether in order to simplify the conversion. As it is wired now the slave board will pickup track voltage with the trailing units pickups, using the 7 pin harness with 2-red wires and2-black wires. I hope it will work I have a set of F Units I need to up grade with the 1905 Kit. Thanks for your thoughts, any addtional thoughts would be welcome.

Bill C.

Thank you for your discussion. I have wondered about the 4 motors and the slave board.

GGG, I have completed the installtion. I hope to load the sound set today and give it a try. I am not an ACS Tech, but I do have a large fleet of Proto Sound engines I enjoy( my engines only) converting to Proto-2 including F and E units plus the UP Turbines an X engines. I have blown a few boards in the process, but it has been fun and a learning event for one that has no background in electronics. I enjoy all parts of the hobby and have for 65 years.

I will post the outcome.

Sound set is loaded in both A units Head and Trailing and they have been tested an they run great.

You do not have to have the PCB and the PV wire contected to operate the motors, apparently they work with all the light funtions. I treated the trailing unit as a dummy with a constant lighting board powered through an off and on switch. I do not use smoke in diesels. This allowed the existing tether to be used and track power was furnished to the slave board with the trailing units pickups. This made for a very simple installtion. THANKS TO ALL FOR YOUR HELP AND HAPPY RAIL ROADING.

Tains41 

After our recent attempt to upgrade the DDA40X the rest of the upgrade kits and associated locomotives are probably going to the MTH Tech for upgrade.  I might be able to handle the layout wiring but the electronic upgrades are a far reach for me.

The DDA40X tested with a short somewhere and that's enough frustration for me thank you very much!  I'll stick to track and turnouts.

It wasn't worth the days I spent carefully following all the instructions and getting advice to save a couple of bucks and have it turn out legs up on the freeway.

Not worth the disappointment.

Sorry you are having problems. I have done well over 100 upgrades and have blown some boards. When I have problems with the project I will walk away from it a few days. Many times I will come back and find the problem and some times I must send the Board to MTH for repair.

Some folks are just lucky to have "the nack" for working with electronics.  My "skill" was working on steam locomotive restoration, e.g. 4449 and 700 ... not electronics. Finally gave that up for riding the Harley and building a layout on which I can see sparks when I hook something up backward before blowing it out :-)

I've blown a few boards myself doing upgrades..it's usually a direct short to ground somewhere