Kumata brass E/E1/E5/E3/E6 Rebuild Project w/ DCC & Sound KMT

[u18b]

Trucks Shorting to the Shell

Reading thus far, we’ve seen how to greatly reduce the chance of the trucks or wheels shorting to the frame or shell in Kumata E units.

But since the frame and shell are always charged on most KMT E units, there is always the risk of a short.

Well, that risk can be minimized even more.   Enter the last E unit made:  The B&O EA and EB set. 



 This set is superior because it is one of the few Kumata locomotives that does NOT have an electrically charged frame and shell.   They accomplished this by isolating BOTH gearboxes from the frame. 

In the other E units, the front gearbox is screwed directly to the frame (with no insulation for the screws).  Therefore, the frame and shell are charged.



The rear gearbox has those insulated shoulder washers. 



The metal screw is screwed into the frame, but the screw never touches the gearbox because it passes through a plastic shoulder washer.  So that gearbox is isolated from the frame.



So KMT isolated both gearboxes in the EA/EB set.   As can be seen here.   There are shoulder washers on all screws- along with jumper wires to both trucks.







So when it comes to other E units like our E1 set, why not do the same thing?


Now, I have a few extra shoulder washers, so I could have used those.  But instead, I simply used the resin screws described above.



So by using resin screws on both gearboxes and using the jumper wire, the shell and frame are now insulated and with the other changes, electrical shorting is almost impossible.





By the way- remember all of this only works if the clear acetate is under both gearboxes.  If a gearbox rests directly on the frame, the process is defeated.

[Cajonpassfan]

Although I sold my Santa Fe E1's years ago, I'm following this with interest (and a bit of fascination). Fabulous work.
So insulating both the frame and the shell solves the shorting problem potential, but how does the power get transferred to the motor? Picking up through the truck/gearbox on one side of each truck only? If so, perhaps wiring the A and B together, with a micro plug, would improve electrical pickup reliability on dead frogs etc? Perhaps you already thought of that...
A great write up, thank you.
Otto K.

[u18b]

Otto, good questions.

The Kumata design is actually pretty simple (some would say primitive by modern standards).  But once the shorting issues are corrected, it is actually a solid design.

It starts with the trucks.  One side, the wheels are insulated, one side is solid metal.  Since the truck frame is solid metal, the electricity charges the solid wheels, the axles, the entire truck and then the gearbox.  So (bottom line) each gearbox is a different polarity.  Electricity gets to the motor by jumper wire- or sometimes simply through the frame.

For example, if your E1 set was a first run, then one motor pole has no cardboard insulator.  The brushcap touches the motor frame.  The motor frame touches the motor mount- which is charged like all of the frame and shell.  So an early E1 actually  only uses one jumper wire.   But all the rest (including my second run E1) have two jumper wires.

By totally insulating the gearboxes from the frame, then jumper wires are required to get the power to the motor.   

Now, as you are observing, each 3-axle truck only picks up juice from 3 wheels.  3 are dead and wasted.    Normally, this is OK on this loco.  But you are correct, running jumper wires between the A and B unit would double the electrical contact.   I'm already exploring this because of DCC sound.


In my next post I'll start working on installing sound.

[Cajonpassfan]

Thanks for the description, Ron, that's kind of what I figured. And yea, since the AB lashup will be operated mostly together, using both will virtually eliminate any power cutouts. I didn't realize you were eyeing DCC, than that's even more important!
Fun stuff!
OttoK.

[u18b]

Installing Sound

I had a ESU Loksound Micro v5 on hand and used it.  The Nano might work better because it is shorter, but right now there is a worldwide shortage of Nanos!  Esu just released some more last week, but they are going FAST.

I first tested the v5 decoder with my Lokprogrammer sound tester to confirm it works.



I also used the LokProgrammer to install an early EMD sound file.

I navigated to the ESU site and searched in the Downloads/v 5 files.
I downloaded and installed a 1 gen EMD dual engine file.

S0583-LS5H0DCC-Diesel-Dual-EMD-12-567-V1-R1.esux

(currently in this list:  http://projects.esu.eu/projectoverviews/search?cat=18&q=emd+dual )

Of course, I already had thought all of this through with lots of planning.  In situations like this I spend a LOT of time thinking, imagining, drawing and making notes.

For example, I found the v5 Micro could NOT fit under the motor without sightly raising the motor and changing the worm shaft interface.  Instead, it will fit where the weight normally resides.  Further, the decoder will fit if it sits on the frame at a slight angle using it’s own internal components. 



So with a workable plan, it’s now time to squeeze this thing in – and I mean squeeze.

There is a small amount of room for a speaker under the worm shaft and in front of the flywheel.  But we need to get speaker wires to it.  Rather than go up and over the motor, I went under.

So I removed the motor support bracket from the frame (motor still attached because of the flywheel)




I cut a groove in the motor support bracket.  Of course, to protect the motor from debris, I taped everything up first.  The bracket is made of brass, so no worry about particles attracted by magnets.



To isolate wires, I needed a circuit board.  So I cut divisions into 4 quadrants for red/black/gray/orange wires.




This will rest on top of the motor and I cut it to fit.  I left an opening for oil for the bearing on the non-commutator end.  I folded the motor tabs and soldered them to the board.    This held it in place.



Since this is an E unit, all I am going to need is a white-wire headlight.  I therefore wanted to remove the purple, green and yellow wires to get them out of the way.  Here you can see purple and green up top.



Rather than remove the shrinkwrap, I use a fresh Xacto blade to cut the wires through the wrap.  Try to cut in such a way that you won’t damage any traces.

Look at this bare board.  There is a trace which runs from the A2 pad at the bottom toward the letter S.  We do not want to cut that trace.  Notice there is a dead spot right where the white printing of “A2” resides.  THAT is where I made my cut.  I did the same for the green wire.



Wires safely removed.



On the other side, the yellow wire was easy to get off with a fine soldering iron.




The decoder is ready.

[u18b]

Time to secure wires- since if not careful, the shell will pinch them when installed.

Holding the decoder as shown, I routed the Red wire in the little gap between the main board and the NEXT-18 board.  I superglued the wire to the shrink wrap about halfway back.  NOTE:  ESU folks need a better buyer for wire.   The “red” wire is really deep orange.    The orange wire is pale orange.  A little confusing at first.

I then routed the blue and white wire the same way on the opposite side.



Here is the reverse side for clarity.



I then positioned the remaining wires in the directions they will go.  Gray and black to the left side of the motor, orange to the right side, and the brown speaker wires straight back (will go through the newly cut groove in the motor mount).



I then superglue the decoder to the locomotive frame.



The decoder cannot lay flat.  But there is a natural angle that is supported by the current electronic components.  See this side view.



I installed the gearbox to make sure there was no obstruction.
Red wire is soldered to the front gearbox tab.   Orange wire to right motor tab.  Gray wire to the left motor tab.  Black wire to the back quadrant on the circuit board.  And the brown speaker wires run through the motor mount.







Here is a close-up view showing that the decoder clears the worm shaft and u-joints.



A test run confirms all is working (at present, blue, white and brown wires are unattached).

[u18b]

I then made a little circuit board divided in half for under the flywheel.  I removed the motor to the side and ran the brown wires to that board.  This board was because of disassembly or repair later. 
I also placed some Kapton tape on the frame to keep the speaker solder points insulated.




The next step was to build a custom sound box for the little Soberton speaker.  Styrene was too flexible when thin, so I used clear acetate window material.  Looks I bit ugly, but I don’t care.
I place a piece of Kapton take on the frame to insulate and protect from the solder pads and the charged  loco frame.  The box had to sit under and clear the worm shaft.  When the size and fit were good, I superglued the speaker box to the Kapton tape and then soldered the wires to the little circuit board.




Of course I constructed the speaker box with clearance from the wormshaft.

[peteski]

Ron,
the speaker seems to be blocked on both sides. On one side it is sealed inside the enclosure, and it seems that the other side is glued to the loco's floor.  The side of the speaker that is outside of the enclosure should be exposed to open air.  Just like the speakers in your home WiFi.

[u18b]

Hi Pete.  Thanks.

Not quite as tight as it looks.

There is a gap at the bottom edge.   The speaker has a solid metal frame that has air opening at the corners (down in my installation).



Though now that I have this working, I may open it up a bit along the bottom edge.

[peteski]

Ah yes. The slots in the speaker housing's corners.  I now see what you mean.

[u18b]

Headlight LED

Time to install a headlight.



The inner headlight casing on this loco is a tube angled downward toward the bottom of the worm bearing so it was hard to know how to proceed.   Of course this old brass loco came with no windows or headlight lens- I’m on my own.



I had an LED- which ALMOST fit.   The lens barrel fit just right after trimming the wider base.   But the problem was with the leads.   They were too close to the tube edge and would cause a short.



Then I had an idea.  Since the barrel was perfect, I milled out the guts of the LED so a 0402 mico LED could fit inside.  I epoxied the LED inside the barrel lens.



I then had to make a circuit board and placed it on top of the forward gearbox.  I used a TCS 4-pin micro plug/socket set.  This will be a high stress point and the 2-pin sockets are too fragile.  The socket had to be positioned at the back edge so that it would clear the nose.



You can see the blue wire runs straight to the socket.   The white wire runs to a resistor and then the socket.  Also note the silver sharpie mark for polarity so plug and socket will match.



Here is the whole chassis so far.



I then installed a plug.  Pins 1 and 2 are soldered together and to a wire…. And 3 and 4 to the other wire.  Note again the silver mark for polarity.



The LED barrel lens was pressed into the headlight tube.



Here is the headlight plugged in.  Later I added some epoxy around the socket edge to give it a little more strength for when the plug is inserted and removed.

[u18b]

Windows

Now time to install window glass.  I cut pieces to fit and then used epoxy to hold in place.
Here is a trick.  Sometimes it is hard to get the clear acetate to press up flat.  So I found foam earplugs can help hold everything in place. 






Another test run.     The sound and lights work great.

[Dwight in Toronto]

Great stuff, and the idea of using foam ear plugs to squeeze things together is genious!

[u18b]

Well, I now have an AT&SF E1A with sound.

What about the B unit?

I saw about 3 possibilities.

1.  Repeat the whole process installing a new decoder.   To be honest, I didn’t want to spend well over 100 bucks to do this.

2.  Drawbar and wire the A and B units together.  That could be time consuming and tricky.  Since the wires could be pinched, the shell would have to have notches cut.

3.  Install a different decoder-  non-sound.

Pursuing #3,  I asked on the DCC board if it was possible to pair up an ESU LokSound v5 with a LokPilot v5.

https://www.therailwire.net/forum/index.php?topic=55753.0

Folks said it was possible  but…..
The sound has a delay (prime mover revs up before the loco moves) and that delay must be accounted for.    You would have to make the LokPilot act like a sound decoder.



OK.  How do you do that?   People assured it could be done…. But no one was absolutely specific about how to do it (change this variable to this, etc.).     

So I decided not to do this.   I’m not an advanced DCC guy like some of you (especially sound).

Thus, I chose option 2.  Wire the B unit such that it sends rail power  (black and red wires) forward to the decoder in the A unit, and then the decoder sends orange and gray wire power back to the motor in the B unit.    Thus one decoder will run 2 locomotives.  Since this LokSound v5 micro decoder can run a much larger HO scale locomotive, I assumed the amp draw of two N scale locos would not exceed its limits.

The down side is this requires semi-permanently coupling of the locos and  the more complex wiring.  Practical matters like storing them in a box becomes and issue.
 The plus side is that I would double the electrical pick-up and make the decoder more reliable over uneven or slightly dirty track.

[u18b]

So here is my A unit chassis.   


My plan is to install a TCS 4-pin micro socket and plug.  That way the B unit could be unplugged and the set does not have to be permanently drawbared together.


Since the wires have to go to the rear, I will mount the socket/plug in the rear over the gear box (left side of photo above).   So I have to get electricity to that spot.

First I made a circuit board the width of the gearbox and cut traces to match the TCS micro socket.  Notice I left room for the plug to the left (front of loco is right).



I then installed the socket.   I used a multimeter to check for any shorts. 



Then then did several things as shown in the next photo.

I superglued the board to the top of the gearbox.  Notice a left a notch so I can get oil down to the worm bearing.

I had to get power from the motor circuit-board to the rear board- without obstructing the flywheel.  So I jury-rigged some Atlas VO-1000 pick-ups.  I had to keep the middle open on this E1 set because the exhaust manifold is recessed down in the roof and will be in the neighborhood.    This is not an issue with the E3/6/5 sets.

I made the black and red track wires go through these VO-1000 strips to the outside edges.   The orange and gray motor wires will go to the inside pins of the TCS socket.



Here is a view of the other side.   The rear gearbox is powered by the left rail (DCC color black).   So I made a short jumper wire to the board.



Here is a side view.



So now let’s move forward.   The front gearbox is right rail powered (red wire).  So I ran a red jumper wire from the tab to the motor pad



Next is gray and orange jumper wires back to the TCS socket.  I placed the wires over the VO-1000 strips to keep them away from the flywheel.



So at this point, the A unit still runs the same.  I’m now ready to work to transition to the B unit.