Nagoya Line or "Sparky"

[Bernard]

Alright here we go with my thread on the Tomix Nagoya Line or as I affectionately call him "Sparky" I have tried many times to install a decoder into this train and good old "Sparky" has blown 2 so far. I'm attaching photos of all the parts of Sparky. I'm am showing the circuit board, the motor, and the chassis. On my attempts I have removed the resistor on the circuit board, have used Kapton tape to isolate the bottom motor bushing from the chassis, attached the decoder wire in different attempts to the trucks and to the circuit board. One problem is that there is no room to attach the decoder wire to the bushing (or terminal) to the underside area. The motor rest snugly on the chassis. The entire chassis acts as a conductor for the bottom bushing. In one attempt I even took out the circuit board.
So here are the photos, any suggestions? (Also notice that the connection to the gears in the trucks are by a spring worm)

[Bernard]

And the rest of the photos. (I did re-assemble Sparky to work on DC control.)

[CaptOblivious]

Here's what I would do: If the engine is a tight fit, and Kapton isn't cutting it, then let it be.

Isolate the motor from the pickups at the circuit board, by cutting traces. Then wire the decoder pickups to the traces where they contact the truck pickups, and the decoder motor outputs to the circuit board on the other side of the cuts. For maximum continuity, you'll have to wire the decoder to both trucks (or rather, the circuit board in two locations).

This bypasses the whole frame-causing-problems issue.

Also, lose the cap: It will (partially) filter out the DCC signal. Don't imagine its a cause of loss of magic blue smoke in your decoders, but you can't be too careful :D

My two cents.

[Bernard]

The fit in the chassis with the wire is just too tight, there is absolutely no room, darn! It's very hard getting the cap back on which holds the worm/driver in place. I think this one has to remain DC.

[CaptOblivious]

The fit in the chassis with the wire is just too tight, there is absolutely no room, darn! It's very hard getting the cap back on which holds the worm/driver in place. I think this one has to remain DC.

How do you mean, too tight? I was suggesting not even running wires in the chassis at all. You only need to connect wires to the top side of the PC board to convert this puppy :D I can post a pic of what I mean later, perhaps?

[Bernard]

The third photo shows that the contact is with the bottom of the chassis. A pic would help.

[CaptOblivious]

The first diagram shows where it appears that everything connects to the PC board. When I made this diagram, I presumed that the traces were on top, now I see that they weren't. More comments in the next post.

The second photograph shows where to cut the traces, and where to solder the decoder wires (may require a bit of scraping of the PC board to expose bare copper, but don't scrape the copper off!)

Does this help visualize what I was talking about earlier?

[CaptOblivious]

Since the contacts are on the bottom, you will need to use a lot of kapton tape to isolate the chassis along the top side (relative to the photos you provided), near the trucks. Or you could put the tape on the board, doesn't matter. And, although the motor pickups have exposed metal you can solder to, you will have to find a way to solder the red and black wires to the truck pickups. I thought you would be able to just solder to the top of the board, but this now seems unlikely. Best bet is to drill small holes, push the decoder wire through the hole, and solder on the underside of the board, just like how the capacitor is soldered in.

[Bernard]

Don - I see what you mean. I can isolate the motor with Kapton tape and will remove the resistor again from the board. I have drilled small holes on the broad to pass the decoder wires through on other attempts. I've run out of decoders and LHS doesn't supply them so now I have to order them online, drat :P
Thanks, pics really help!

[CaptOblivious]

And…? Any luck? Third time the charm?

[Bernard]

Hi Don - Yep, good old Sparky is working fine now....in DC that is. He blew another decoder and I converted Sparky back.  :-[

[CaptOblivious]

Hi Don - Yep, good old Sparky is working fine now....in DC that is. He blew another decoder and I converted Sparky back.  :-[

Being a Tomix model, would you mind adding all the gory details to the Tomix & DCC thread?