Model Power Pacific 4-6-2 Improvement: Fixing a Disaster and making a Pearl

[u18b]

Could you put a mini torch on just the worm and heat it enough to expand it without destroying the motor?

Don't know.  I'll see what Max can do.

[u18b]

Time to improve the stock incandescent lighting which has two problems.

First, and most important, the light gets power from wipers on the wheels.  This is bad for three reasons: collecting dirt, flickering connection, added friction on the driver.




The second problem is that with a decoder installed, the incandescent bulb will be on all the time and will eventually burn out.  Bulbs don’t generally last near as long as LEDs.

So my goal was to do away with the wipers and hard wire an LED.  But this is no easy task in a boiler with a metal shell.

On the trashed Pacific, the guy that did the bad sound install ran the blue and white wire on the side up under pipes- which was a good idea.  But he cut grooves in the metal shell and made a mess.

So I wanted use his basic idea but better.

 My first thought was to run some very thin wire along the chassis frame from my spring contact board to the light mount (purple).  I even tried it.

But it didn’t work because the gap between the boiler worm slot and the geartower which fits into that slot is too tight.  It would pinch the wires at the blue spots.




So then I turned my attention to the boiler.
How could I run wires from my spring pads on the left to the hole for the light?

The blue areas are where the pinch happens.  The red areas are not possible because of the drivers.




But the other guy used the piping detail to hide part of his wire path (yellow)- and that was a good idea.  But I decided on a different path.




The tiniest sheathed wire I’ve owned comes on LEDs that I buy from Asia.

0402 LED are so tiny they are VERY difficult to work with- so I started buying pre-wired.  Here is a good price on a 40 pack.
I found the wires are just as valuable as the LEDs.   I trimmed the LED with about 2 inches of wire and saved.  The excess black wires were used here.

https://www.aliexpress.us/item/3256801789442506.html





I used an SMD LED, warm white, in a 3528 size.  That almost filled the hole in the boiler.   I soldered a resistor to it and the black very fine wire.
I then heat-shrinked it to protect it.  And I added extra heat shrink to make the base fatter to be less loose in the hole.






Now came the very time consuming part.  The sheathing on this wire is very slippery.  I used 5 min epoxy to tack it down.
Here is the first tack between the LED and the worm.
The epoxy required several hours to cure well.




I then removed the piping and the power reverse on the side of the boiler.  They are just pressed on.






With the epoxy cured well, I then routed 90 degrees up toward the walkway and then left toward the cab.




More epoxy was applied and allowed to cure.  Taped removed hours later.   I know it looks awful in this shot because it is shiny… but wait.




When the piping detail is placed back on the boiler, you can see that the wires are already mostly hidden.




Before I solder to the pads, I need to know which LED wire is the right rail wire (when in analog).  I marked the right wire.




I unsoldered harness wires from the pads and then trimmed and soldered the LED wires to the pads.  The harness wires were then soldered back.




Re-assembled.
And while not as bright as I would like, the LED (left) was actually brighter than the stock bulb (right).

[u18b]

Here is the loco reassembled.  And you can’t even see the wires or epoxy.



I was pleased with the results.

[Dwight in Toronto]

My version of this model is a maroon-&-gray Canadian Pacific with the semi-streamliner panels flanking the boiler.

When I installed an ESU 58731 and speaker in the tender, I ran a pre-wired 0402 LED of the same type up to the headlight.   Those wires were so fine, that they were easily concealed along the lower edges of the boiler, and were virtually invisible once the side panels went back on.

For the LED, I believe I popped off the front boiler cover, filed a small groove to accommodate the wires, and simply inserted the LED into the light hole in the casting.  The cover was then pressed back in place.  The protruding wires are just visible where circled in the pic.  After all these years, right up until this very moment when I snapped this pic, I never noticed the loco number “2402” embossed right on each side of the lamp housing itself!

I vaguely remember getting into the boiler to remove the old lamp bulb and the wiper pickups, but that part is a bit hazy.

The steam, whistle and bell sounds make this one of my favourite models, and the LED was a huge improvement over that pathetic light bulb.  After making my own axle wipers for the tender track power pickup, it’s also a very good runner.

[peteski]

Yes, the smokebox front is a very nice lost-wax brass casting with a plastic back. Makes sense knowing that the company that made these makes highly detailed brass models.The smokebox front should easily come out just by pulling it out forward.  That makes the headlight installation much easier.

[u18b]

Dwight,
Thanks for posting that.  You are correct, it is not very noticeable.

However, on my second one, I'm going to route the wires internally.
I'll post photos when I do.

Basically, I'll do exactly what I did before but will make the wires longer, run them through the boiler nose and mount the LED in the smoke box very close to the headlight.

[u18b]

For the second Pacific, I wanted to mount the LED in the nose.

But there is a weight in the nose which must be removed.




First, pull the smoke stack (which locks the weight in because the mounting pin is very long)




Grab the headlight and pull the nose off.  The light pipe is now exposed.




Since the smoke stack locks the weight in place and is now removed, simply grab the light pipe and pull the weight out.




The light pipe is pressed into the weight and can be removed.




With the light pipe removed, you can see a channel in the weight where wires can now be routed- which when inserted in the boiler, is on the bottom- as shown here with weight and light pipe inserted.




With the light pipe removed, there is a narrow end and a wide end to the channel.  The narrow end is front and the wide end is rear.




This is the nose end where the LED will go.

[u18b]

A 3528 LED will just fit in the groove in the nose end of the weight.  But I wanted extra room for soldering, insulation, etc.   So I used a motor tool to open the slot in the nose end a bit more.





My reference point for milling was the ramp in the metal.






I then took a 3528 LED and soldered a resistor at a right angle.



img]https://www.therailwire.net/forum/gallery/41/medium_1277-110624175130-413071853.jpeg[/img]

[u18b]

And then soldered two fine wires- one to the LED and one to the resistor.   This was tricky and required extra hands as grabs on a stand.




I conformed the outer wire to the LED back and added ACC around the contacts and on the back to insulate it all a bit and hold the wire in position.




As before, I then took the assembly to my layout and identified which wire would go to the right rail when running forward so the light would work in analog mode (each of my Pacifics is dual mode because I used a socket in the tender which can host a decoder or a jumper plug for analog).

Since a diode only works in one direction, I simply put the throttle on 50% in the forward direction and see which way the LED would come on.   The right rail wire is then marked with a silver Sharpie marker.

[u18b]

Now I had to make a decision.  Do I make this modular or not.  If this is hard-wired, then I won’t be able to remove it without cutting wires and maybe even starting over.

On the one hand, probably not an issue since (so far) I’ve never even had an LED die on me.  But….. it would be bad if the LED died on this loco.  So I decided to do the extra work and go modular.



I then got a 2-pin TCS micro plug and socket.




What I’m going to do will require extra resilience in this little socket.   I do this by added epoxy around it.  But liquid epoxy could imbibe up the holes in the back and clog the socket.




So I cut some slivers of masking tape and covered the bottom of the socket.




I added shrink wrap to the resistor on the LED, and then trimmed the wires and soldered to the socket.




I used the weight as a guide for length.  Actually, mine is probably a bit too long.






I added extra shrink wrap around the socket to add thickness so that it would be a little snug in the slot in the weight.




I folded excess wires and added epoxy all in the channel keeping it away from the socket holes and the face of the LED.






The modular weight/LED headlamp is ready.




Added wires to the plug and then tested the light module.  The light was a tab bluer than I wanted.

[peteski]

99.9% of LEDs have their cathode identified some way. This LED has one beveled corner - that is cathode.  That would connect to the left rail for the front headlight, but it never hurts to verify.

I will also give you a warning. White LEDs have very low reverse voltage rating (as little as 5V) and anything over that can destroy the LED.  You should seriously consider protecting that LED by adding another diode in the circuit.  Also, when a DC loco encounters brief disconnects from the rails (when it travels over dirt), the still rotating motor armature (acting as a DC  generator) will  generate BEMF voltage in reverse polarity of the track.  Those small spikes will make the front LED flicker when the loco is running in reverse. Adding a capacitor will shunt those spikes preventing flicker.

Here is a diagram with some examples I recently posted in another thread about adding white LED headlights to a DC loco It:

[peteski]

Added wires to the plug and then tested the light module.  The light was a tab bluer than I wanted.

You can paint the front face of the LED with a transparent orange paint (like a Sharpie, or Tamiya transparent orange) to "warm up" the light.  The orange will filter out the blue light and make the light look like warm incandescent light.

[u18b]

You can paint the front face of the LED with a transparent orange paint (like a Sharpie, or Tamiya transparent orange) to "warm up" the light.  The orange will filter out the blue light and make the light look like warm incandescent light.

Yep... I was planning on this.
I already have some paint.  Will just need to thin it down since it is not "transparent".

[u18b]

When the weight is inserted into the boiler, the socket lines up with the hole in the boiler underside.  The module weight/headlight is finished.




I now turn to the plug.  I added heat shrink to the plug.   I then found added ACC helps hold it all together better.




A test fit inserting the plug into the socket.  All is good.  It is OK for the heat shrink to stick out a bit.  There is plenty of room.

[peteski]

Yep... I was planning on this.
I already have some paint.  Will just need to think it down since it is not "transparent".

Get an orange Sharpie. Those are available pretty much everywhere.  I suspect that standard opaque paint, even thinned will not be quite the same.