Switching between series and parallel wiring

[RNF]

Hi,
Yesterday, I decided to convert 2 of my Williams diesels(GG-1 and GP-9)to series wiring. I did this for a few reasons. One...both those diesels pull a line of MTH passenger cars and they barely illuminate at the low voltages that those diesels previously ran at. 2.....I recently bought a PW Lionel NW-2 switcher and really like it's low speed crawl. My Williams engines take off like jack rabbits. So, I found Joe's directions for the wiring and went at it. The GG-1 went well and I got the performance I was hoping for. My GP-9 was not as easy. I wired it up and it didn't work. Wired it again and it didn't work. So, I compared the connections on the circuit boards of my other engines and sure enough....a blue wire should have been yellow and a yellow should have been blue. Colored wrong and connected wrong (from the factory).  I straightened it out and did the wiring and it works.

Anyway....reason for this post.....I would like to put a switch in that will enable me to switch from parallel to series and vice versa without having to unsolder and rewire. I need to know a couple of things.  I've been searching for a switch that can handle this. I figured it would have to be some type of double pole, but haven't had any luck locating something small enough. A knife switch would work, but they are large. Second....how would the wiring work connected to this switch? Any advice about this will be welcomed.

The only downside of doing this series wiring that I can see is that I will have to be very careful about not giving it too much juice (I use a ZW) which will probably blow the big, 5 surface LEDs I have in those engines.

Thanks,
RNF

[Joe Satnik]

Dear RNF,

Hey, thanks for the heads-up on the wrong color factory wiring.  

Well, the switch you are looking for is a

Radio Shack 275-636 flatted metal lever DPDT switch, 6A 125V.

Let's number the terminals on the back of the switch like this:

1 2
3 4
5 6

You must decide if you want to cut your wiring, which will void your factory warranty.  

With the proper connectors, you could make this plug and play (and completely reversible)  however, a 1/4" hole in the chassis (to mount the switch) might be a give away that some mods were done to the loco.

If you want to cut wires, cut them somewhere away from the ends, so as to leave enough wire length to strip and solder.  

First, figure out which color wires to work with.    

Inspect the wires connected to each of the motors.  Find the motor terminal with a colored dot (my 2004 era Williams GP-38 is red) next to it.  

For correct factory wiring, one truck should have a yellow wire attached to the dotted terminal, the other truck should have a blue wire attached to the dotted terminal.  

For correct factory wiring (opposite color wires on motor dots):

Cut one color wire between the reverser board and the front truck.  

Cut the opposite color wire between the reverser board and the rear truck.  

This gives you 4 wire ends:

Front truck wire from board (FTb)

Front truck wire to motor (FTm)

Rear truck wire from board (RTb)

Rear truck wire to motor (RTm)

Wire the switch as follows:

RTb 1 2 FTb

RTm 3 4 FTm

con 5-6 connect 5 and 6 together.

Use heat shrink tubing if wire-to-wire splices are needed.  Inspect the connections on the back of the switch for shorts.


For incorrect factory wiring (same color wire on both motor dots),

Use the instructions above, however, change the word "opposite" (above) to "same".


If you are worried about your LEDs, double the resistance and wattage of the series (AKA "voltage dropping" or "current limiting") resistors.  

For example, if you have 1K Ohm (=1000 Ohm) 1/4 Watt resistors, then use 2K Ohm 1/2 watt resistors.  

Since 2K Ohm is not a standard value, use 2.2K Ohm (a little dimmer).

Hope this helps.

Sincerely,

Joe Satnik

Edit: moved  "Use heat shrink.." and "Inspect the connections.." sentences up 2 lines. 

[RNF]

Hi Joe,
Wow.....that was terrific. I was at Radio Shack trying to decide on a switch and left because I wasn't sure if it should be AC or DC compatible. You made it easy.   As I've already cut wires to do my wiring, I'll follow that path. Your directions couldn't be clearer. I'll try to wire it up tomorrow and let you know how it went.

One question.....I do not have resistors in the circuit. Are you saying that I should wire one in on the series side of the switch? I've done some mods with LEDs and have found that finding that right resistor is very hit and miss and that the results are nonlinear. I've got a tender that I put tail lights into and used resistors to dim them to my liking, but it was trial and error.

Thanks for you help. It looks great and I'm looking forward to trying it.

Roger

[RNF]

One other question.....if I opted to use a slider switch could I use the 275-403? I haven't decided if I want to switch protruding to the outside or have it inside. How much does the amperage rating for the switch matter?

Thanks,
Roger

[Joe Satnik]

Dear Roger,

You could get away with as small as a 3 amp switch.  Just make sure no terminals are touching (shorted to) the chassis. 

More on LEDs later.

Sincerely,

Joe Satnik

[Joe Satnik]

Dear Roger,

Yes, the 275-403 switch would work for series/parallel motors wiring (3 Amp rating). 

My first calculation was wrong, the switch needs only to be half the rating of the 6 Amp reverser board.

You could still use a toggle switch if you shortened (sawed off) the paddle and painted it black.  You could use any DPDT switch small enough to fit and rated 3 amps or greater, and 20V or greater.

Change subject:  LEDs. 

Are you wiring the LEDs in the motor circuit?  Hadn't thought of that.  The drawback to that is no LEDs are lit while in neutral.   

Tell me what kind of LEDs you have (description, color, current and amperage rating, make and P/N if possible) and how they are wired up.  Any LED needs a series resistor or it would burn up.  Some (but not many) have built in series resistors.

Hope this helps.

Sincerely,

Joe Satnik       

[RNF]

Hi Joe,
I really appreciate your advice on this and all the work you've done on it. Invaluable. Initially, I thought the switch would be internal, but I like the idea of it protruding to the outside, so I can just flick back and forth between series and parallel. Terrific.  I'll just figure out a spot for it inside the shell and cut off enough of the toggle so it doesn't contact the track.

As for the LEDs I use in my Williams engines....they are big 5 surface LEDs........
Xenon White 5 SMD 5050 360° BA9 BA9s LED Bulbs 1895 H6W  (replacments for #53 and lots of others). Bayonet mount and go right in the socket. Awesome amount of light. I use amber cellophane inside the shell lenses to "warm up" the light as these don't come in warm white. They work well in the Gp-9, but are awesome in the GG-1 as that one has a better lens.

Regards,
Roger

[RNF]

Hi,
Just to let everyone reading this how the wiring went.  I used a Radio Shack 275-403 switch  for the GP-9. There is a slot in the chassis over the front truck that I used for the switch. I Gooped it in directly in front of the light socket upside down so that the toggle goes into the slot. I had to Dremel down the toggle itself so that it wouldn't hit the truck and also Dremeled the edges of the switch so the triangular front of the shell would go over it. It works like a charm (especially after using contact lube inside the slider).

As for my GG-1. There aren't any openings in the chassis for a switch. I didn't want to make holes in the chassis or fuel tank. Joe suggested that I use a switch that I could access through an open window. I thought about that for awhile and decided on a Radio Shack 275-614 mini toggle. I Gooped it to the side of the shell so the toggle sticks up inside the window. It was harder to wire than the slider because of it's smaller size and I had to put shrink tubing on all 6 solder connections so they wouldn't touch one another. I've been using a toothpick to flip the switch and it also works great.

I feel that these mods are a terrific addition to these locos and gives me power and speed on the parallel connection as well as low speed crawl and brightly illuminated passenger cars on series. And they go plenty fast on series if that's a concern.

Kudos to Joe for all the advice and encouragement he gave me with this!

-RNF

[Joe Satnik]

Dear Roger,

Thanks for the kind words.

Glad I could help.

Now if I could just get my passenger car anti-flicker mod noticed....

Sincerely,

Joe Satnik