MT SW1500 DCC conversions

[mu26aeh]

Outside of the one or two people here I've seen convert their 1500 to DCC, has anyone else attempted ?  I received mine the other day with Digitrax DN126m2, taped under the decoder, tape between frame halves, tape on underside and top side of motor, and tape around where the wires attach to motor/brush.  I put on programming track using Digitrax Zephyr, go to read the decoder, the light lights up, then Zephyr shows error message.  I've had d nd, d nA, and d nr , depending on different times I've tried it.  Can't figure this thing out.  In a stroke of dumb luck, I did place on tracks and the light comes on, but no motor control on any address it could be.  And more importantly, no magic smoke.  Engine runs in DC mode with stock light board in place using 9V battery, in both directions.  Using 9V with DCC board, I get nothing.

[tehachapifan]

I had a successful (second) install but not without letting the smoke out of my first install attempt (thank goodness for goof-proof warranties!). My first install fell victim to a motor lead solder joint poking through the insulation tape and making contact with the frame, which was not causing a problem as a DC unit. Aside from that issue, I also vaguely recall one or both of the motor lead "plug-in" connections at the decoder being a bit finicky. I think I had to strip a tiny little bit more insulation off of one or both of the wires so they would seat in a little better. Be careful though as I also recall that, if I was to strip too much insulation or push those plug-in wires in too far, the wire ends might've gotten close to touching the worm below the decoder (replacing the shell can push on those wires too). This might account for the no motor response problem but I don't know about it causing the inability to do any programming (I'm not familiar with those error codes). Your mileage may vary.

[RBrodzinsky]

I, too, had a motor lead to frame short that smoked my first decoder. Took the whole frame apart, put kapton tape all around the motor cut out space, and double checked continuity before putting in the second one. Yes, good proof warranties must be eating up a lot on this model.

Of course, worked fine in DC mode. You might want to pull the DC board, then check for motor/frame short.

[mu26aeh]

I did clip the wires even with bottom of board, both sides were poking thru.  About the only thing I can think of to do is actually replace the wires.  I have tape everywhere, hard to imagine something is touching.  Plus it if were, the decoder should have gone up in smoke when i put on the layout.  I'm wondering if it's the decoder itself.

[Philip H]

Could always be.

I asked in the last sw1500 dcc thread - and got crickets - but has anyone done this with the TCS decoder?

[tehachapifan]

Did you say you rec'd the unit with the decoder already installed? If so, have you tried resetting the decoder to factory defaults? Might be worth trying even if you just installed it new.

[mu26aeh]

No, I bought the engine and decoder separately and installed it myself.  I can't reset it, always comes up error.

[rrjim1]

I found that the Digitrax board was a little to wide, and the wires were to large. I remove the wires and replaced them with TCS ones and soldered a very short piece of the old wire on the ends that goes into the decoder board. I also glued a small thin piece of plastic between the frames were the fuel take goes to keep them apart. I filed down both sides of the Digitrax decoder board were it goes into the frame, so it would fit correctly. I didn't see any need for tape, none used. I have two Reading units and now after a lot of work they look and run great.     

[mu26aeh]

I replaced the wires and still nothing.  This is really frustrating 

@Philip H , you may find out your answer to the TCS decoder today.  My LHS only has that one in stock for the 1500, I may get it to see if it is my decoder that is bad.

[peteski]

Be careful wit this install. There are few threads on TRW (use the search function) which mention that there is a problem with this loco where either the motor leads and or components on the decoder can short to the chassis and the decoder will smoke!!  IIRC, the latest thread on this was by Ed K.  My advice is that if you want your loco to run tonight, find those threads and ust that info to correctly install the decoder..

[Philip H]

Be careful wit this install. There are few threads on TRW (use the search function) which mention that there is a problem with this loco where either the motor leads and or components on the decoder can short to the chassis and the decoder will smoke!!  IIRC, the latest thread on this was by Ed K.  My advice is that if you want your loco to run tonight, find those threads and ust that info to correctly install the decoder..

Given his references to copious tape use and wire considerations I think he has read them.

[RBrodzinsky]

I asked in the last sw1500 dcc thread - and got crickets - but has anyone done this with the TCS decoder?

My install was with the TCS decoder.  I never saw any smoke, but the decoder was definitely a goner. After the initial install (without my checking for frame/motor shorts), there was a dead short across the two input pads of the decoder (when out of the loco).  TCS exchanged, no issue.

[mu26aeh]

Ok, so some limited success.  I brought home decoder from TCS.  I removed motor from engine, and hooked up dc board.  I placed in clothes pin, set that in vice, and applied power from Zephyr on 00 from the leads.  Engine runs.  I took Digitrax board and did same thing, on address 03, I get a light but nothing else.  I hooked up TCS board, on address 03, no light but motor turns.  I hit 0 on Zephyr, turning light on, touch leads back to TCS board and I have light and motor.  So right now, I'm thinking Digitrax board has issue with motor control.  Will check back later when I get a chance to put TCS board in frame.

[tehachapifan]

That sounds promising. Keep us posted.

[mu26aeh]

Success !!!    Installed TCS decoder, after changing the wires back out to the old ones, new ones were too think, and ta da !  We have a working DCC 1500

20151226_160955 by Adam Henry, on Flickr

So I guess the Digitrax board is bad, now will MBK take it back (nope, defective product goes back to manufacturer), or have to go back to Digitrax and possibly ask for a different decoder since I don't need one for the MT any more ?