Tomix HC85 dmu + dcc decoder

[Anvalo]

Recently i converted the Tomix HC85 DMU to dcc.
For this a wired Doehler & Haass PD10MU decoder was used and some pictures were made of this conversion.

This report is a bit lengthy, hope you don't mind.

 

Both cars are very easy to take apart.
This was the first Tomix for me to disassemble and i was pleasantly surprised by the straight forward design.

 

The same circuitboards with 2 leds are used in both cars.
These leds are both white and the light is guided by the transparant and red lightpipes in the cabine.

On the bottom side are 2 square copper pads which are connected via the small holes to the top.
It's very important to drill these out so there's absolutely no connection left.

 

Top and bottom view of the circuit boards.

 

There's also a little switch to disconnect the lights.
Tomix was so kind to print some arrows next to the leds to show which way the current flows.
This made things a bit easier for me.
Used a Dremel with a tiny bit to change the circuit on this board because both leds have to point at the decoder.
Had to hold my breath and use my trusty old magnifying lamp, without it i'm lost 🧐.

 

A small slot was made to create some space for the wires.

 

This time i used the proper wire colours for all connections.
The positive wire coming from the resistor is black (left side of the loco) and connects the 3 new copper traces.
This was very fiddly. In real life it's much smaller than this pictures shows. 

 

Next job was to figure out how to get the 2 wires for the lights to the second car.
Came up with this solution, two tiny strips cut out of copper tape.

 

The first decoder wires are soldered. Black wires on the left and red on the right side.

 

On the underside of the circuitbord the grey and orange wires are soldered on the copper pads for the motor.
Note the drilled out holes, there's no connection left to the top (very important).

If there is still a connection the decoder could go up in smoke. 

 

The decoder held in place with some double sided tape.
After this picture i had to reposition the decoder a bit because the body wouldn't snap in place, it was a tight fit.
All the white and yellow wires are also soldered now on the copper tape.

 

At the rear end the 2 wires for the white and red lights of the second car.

 

Had to repeat the same job with the Dremel to change the copper traces as in the first car.

The 3 copper pads are connected with some red wires this time because the positive lead from the resistor is now connected to the right side (red) of the track.

The colours really doesn't matter but i wanted to do a proper job this time😇.

 

All wires are hidden now, nothing to see from the outside.

 

Final job is to connect the wires and close the second car.

Maybe i will use a black sharpie marker to mask the 2 wires between the cars.

The gap is only a few mm but the wires can be seen.

 

The last pictures also shows that the original Arnold couplings are replaced by Kato 11-702 couplings.

This looks much better.

 

Next decoder installation to show is one of the Kato DD51's.

 

André

[Kingmeow]

Thank you for the great explanation and fabulous pictures.  The pictures are wonderful; big, bright and clear!  I look forward to your further decoder installations.

 

My Kato DD51 is on my bench for a Digitrax DN163K4A decoder install.  A friend of mine installed it in a matter of minutes.  He said he had to cut one of the light pipe short to clear the SMD LED on the decoder.  Other than that it was straight forward and the loco runs nice.

Edited February 3 by Kingmeow

[Anvalo]

@Kingmeow

Thanks,

The DD51 is indeed very simple to convert to DCC.

Here's a picture i took earlier.

Just snip of a piece of the front light pipe and you're done.

I used these Digitrax decoders before on my Rhaetian Railway engines and found out that they are slightly thinner than the original board.

So i put some extra tape under the decoder (right side) to make a more reliable contact with the frame.

[Kingmeow]

If the decoder is thinner than the original light board, people often put a small dab of solder on the contacts.  If too thick, you can easy file the solder down as appropriate.  Solder files very easily.

 

BTW, I have the identical DD51 as the one you pictured.  🙂

[chadbag]

I've had some of the lightboard replacement KATO locomotives where I took a small piece of wire and soldered it instead of relying on the contact with the board.  My TCS boards (same formfactor as the Digitrax) only had pads on one side in some cases and in any case it made it more reliable.

 

[Kingmeow]

I'm assuming you solder one end of the wires to the decoder but where/how did you connect the other ends to?

[chadbag]

13 minutes ago, Kingmeow said:

I'm assuming you solder one end of the wires to the decoder but where/how did you connect the other ends to?

 

I'd have to find one to look.  I just remember soldering a wire instead of relying on the contact.  It was also due to using a TCS which didn't have double sided pads.  My stuff is in storage now but I think I mentioned it in a previous thread.  I'll try and find it.

 

 

[chadbag]

3 hours ago, Kingmeow said:

I'm assuming you solder one end of the wires to the decoder but where/how did you connect the other ends to?

 

Which digitrax decoder are we talking about again (of the two main styles)?  I'm trying to remember why or find info I may have posted.

[Kingmeow]

No Digitrax in particular.  I was going off your comment that you solder wires for your TCS decoder(s) (4 posts up).

[chadbag]

59 minutes ago, Kingmeow said:

No Digitrax in particular.  I was going off your comment that you solder wires for your TCS decoder(s) (4 posts up).

Yes.  I wanted to know what Digitrax were talking about so I could figure out which TCS I was using so I could figure it out since it’s been awhile.  

Edited February 4 by chadbag

[Kingmeow]

Ah!  I think where we last left off was DN163K4A for the Kato DD51.

[chadbag]

1 hour ago, Kingmeow said:

Ah!  I think where we last left off was DN163K4A for the Kato DD51.

I think the one I had was a TCS replacement (K0D8 of some sort) which is a drop in for Digitrax DN163K0x (now DN167K0x per YankeeDabbler).  The Digitrax had copper on both sides of the board and TCS didn't and contact fit wouldn't work so I used a wire.  I had another one, can't remember which it was (which TCS or for which Digitrax I was using it) that used contact with the clips to hold it in where that wouldn't work reliably so I just soldered the wire on. 
 

When I eventually get unpacked I'll search for them if I cannot find a report here in the forum about them.