RK,

Here's a simple forward and reverse circuit showing only one resistor and LED pair:

Left wheel pickups  ---->-- Bridge (~ac)

Right wheel pickups ---->-- Bridge (other ~ac)

Bridge (+) ----->---- (+) ------->----Resistor-->-- anode
                           Capacitor                                LED
Bridge (-) -----<----- (-) ------------<------------ cathode

Hope this helps.

Sincerely,

Joe Satnik

From 1980 catalog:

http://hoseeker.net/bachmanninformation/bachmanncatalog1980pg22.jpg

Different than 1987 version.

Not sure why this copy-pasted link doesn't work. 

You can find it manually by going to the HO seeker site and working your way down to it.

Joe

Ihaets,

Wow, this HO seeker website is quite useful.

http://hoseeker.net/bachmanninformation/bachmanncatalog1987pg06.jpg

Is this your loco?

I didn't notice a set that included the DD40X in the few years of catalogs that HO seeker has posted, only separate sale.

Is your DD40X from your set?

Regardless, it would help if you had some kind of padded cradle to hold your loco upside down for troubleshooting.

You could build a "U" shaped channel out of scrap wood and throw a towel over it for padding.

Another possibility, a long shoe box.

Thanks.

Sincerely,

Joe Satnik

RG,

Take the loco off the tracks (lit cars only on tracks) and try:

Forward power until the LEDs are satisfactorily bright, off (until the LEDs die),

Repeat for reverse power.

Let us know your results.

Thanks.

Sincerely,

Joe Satnik

Ihaets,

Your make/model must be different than the diagram linked by Rich.

You stated: "When front is lifted front wheels want to go backward",

which leads me to believe that both trucks have motors,

yet the Bachmann DD40X diagram shows that the front trucks are non-powered.

Is this a Bachmann train set, or some other manufacturer?

What is the (road) number on the side of the loco shell?

Do you still have the set box?  If so, what is the manufacturer, set name and set number?

If not, check for a manufacturer's name on the bottom of the loco and all other pieces of the set.

Thanks.

Joe Satnik

Pull the shell and check the wiring.  

Each motor should have a "dotted" terminal, and a "non-dotted" terminal.

The left wheel power should connect to a dotted terminal on one truck, and the non-dotted terminal on the other truck.

The right wheel power should connect to the non-dotted terminal on (the same) one truck, and the dotted terminal on the other truck.

Joe

Edit: Spelling

In which direction does it want to run when the front wheels are lifted, back wheels in contact?

Which direction for the front in contact, and the back lifted?

Has someone worked on the loco since the '80s?

Thanks.

Joe

Ihaets,

I would guess that your front truck is turned around 180 degrees.

Joe

Edit: Added "180 degrees".

JB,

The wheels will not rotate from the outside because of worm-gear drives.

You will need to spin the flywheel from the top of each motor.   

If your Williams semi-scale GG1 is anything like my Williams-by-Bachmann (WBB) scale GG1, there are 6 screws holding the shell on,

2 above the front most truck, 2 above the rear most truck, and 2 exactly in the middle.

If the flywheels spin freely, check to see that the wiring from each driven truck is plugged into the reverser board.

You will need a Volt-Ohm meter for your next troubleshooting step.

Hope this helps.

Sincerely,

Joe Satnik

I would guess that the age of your loco is probably closer to 15 or 20 years old than 10.  True Blast 2 was available in 2003, and your loco is at most a True Blast (One).

Try taking the shell off and spinning the flywheels on the tops of the motors.

They should rotate fairly easily, and the driven wheels of the truck underneath should rotate at a much slower rate.

Joe Satnik

JB,

Does your sheet of paper say anything about activating a bell ?

Thanks.

Joe

RG,

A Rectifier Bridge should have 4 terminals, two "~", one "+" and one "-".

If it does not, put up a picture of what you have, and let us know its manufacturer and part number. 

Thanks.

Joe Satnik

Dear All,

I'm not sure of the difference of  DC vs. DCC (an AC-like signal).

A quick short could occur if the wheels are too wide and the wheel coming off the frog

touches both the stub rails, which are close to one another just after the frog.

It may be that a quick short occurs on DC too, but the momentum of the train just carries it through. 

A quick short might be enough to "mess-up" a DCC command, or blow a quick acting DCC breaker.

The only other possibility is inductive or capacitive coupling of the signal is somehow

increased with the frog attached, which is a bit of a stretch,

as the signal frequencies are not that high.

Hope this doesn't confuse.

Sincerely,

Joe Satnik

Hi, PJ.

Ammeters and Volt-meters are very nice to have on a power pack.

They are especially useful for troubleshooting locos.

Consider yourself lucky, as this model is no longer made, and hard to find.

 

Sincerely,

Joe Satnik

Edit: Added photo and clarification.

Hi, Will.

Just know that if they choose to replace it instead of repair it,

you may not get a DCC-ready Decapod back, as they are not currently being produced.

What track voltage does it take to get it moving?

What track voltage does it take to keep it moving? (Before it blows the breaker.)

Is the dummy plug in its proper location/orientation?

Thanks.

Joe Satnik