You would probably need to add a wiring harness like other locos use between the loco and tender to carry motor and lights - the existing power connections in the drawbar should be usable to link the loco and tender power pickups. Never having taken an MTH steam loco apart, I can only speculate that their 'wireless drawbar' uses something like an I2C connection between the boards to transfer commands as a digital interface. At total of 4 connections in the drawbar would give you the 2 lines for communication plus 2 wires for power.
I guess if some other company wanted to do similar without violating the MTH patents they could try to squeeze a third connection in there and use SPI. It's an interesting idea that seems a bit overkill, other than ease of connecting/disconnecting the tender. I've seen installs done where the wires are bundled and look pretty much like the various connections that exist on the prototype, instead of a flat ribbon of wire down the middle, so it is possible to make it look good but still have conventional wires between the two.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
If you want the best motor control that includes sound: Loksound or TCS.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
One of the local DCC gurus atempted to replace the PS-3 system in 1 of my GS-4's but, gave up after trying to get info from MTH and hearing from brand X and brand Y that some MTH locos fried their decoders. I have emailed Tony's Trains asking if they can make the conversion but have not heard from them yet. I think the lighting negative and positive issues could be worked out. I also do not care that the smoke system would be gone.
There might be digital info going through the 2 wire drawbar however, I think the circuit board in the tender is for sound only plus maybe the remote controlled rear coupler and rear headlight. The board in the boiler is for motor, engine lights and smoke unit. Since the tender has power/signal through it's trucks and the engine has power/signal through all 4 axles the 2 boards may be independent of each other.
Hi,
I have only one MTH locomotive, the Empire State Express Hudson. I plan to replace the MTH decoder with Loksound sometime in the future, too. One of the stumbling blocks, for me anyway, was the engine-tender drawbar connection. AFAIK there are only two wires in the drawbar. I would need to add a jumper plug so that I have at least five or six circuits? A motor pair, headlight pair and rail a/b pair.
Does MTH use some kind of encoding to get all the functions between the tender and engine on only one pair of wires? I already ripped out the smoke unit so that is not an issue.
I believe some MTH steam has a four-circuit drawbar connection.
I'll have to take another fresh look at this decoder replacement sometime soon.
Regards, Ed
There was an article somewhere - I think in the RPM Yahoo Group, although it was an MTH diesel that was done. The biggest problem is that MTH DCS boards use a negative common for the lights, while DCC uses a positive common and the function wires are the negative side (current sink). This means in the case where there are multiple LEDs on a board, a bunch of trace cutting and rewiring needs to be done to hook up a DCC decoder. This may not be as big a deal on a steam loco where each light may be completely independent, but you never know what's inside until you open it up. It's not impossible, just a pain.
I have 3 HO MTH PS-3 DCS/DCC SP 4-8-4 locos, 2 are GS-4’s and 1 GS-6. One of the GS-4’s and the GS-6 have been repaired at MTH a total of 6 times under warranty. They still have motive control problems. My question is; has anyone successfully replaced the PS-3 circuits with Tsunami or Loksound?