This installation documentation is for the HO Scale MTH SD70ACE. This installation uses the T6XP-LH decoder, and was performed by A.C.E.
We recommend using a foam block as shown below for doing decoder installation work. They are a great aid in holding the loco in place and help to prevent damage to the detail parts.
The first step is to remove the shell from the chassis. To remove the shell you must do two things. One: remove the handrail from both sides of the loco. Also remove the handrails on the front only where they attach to the loco shell. We found it was easiest to remove the handrails on the front with tweezers. The handrails on the side we did by hand. Gently pry upwards on the hook at the top of each rail post as you push the wire rail out of the hook. The rail will come out very nicely this way. The rail itself is metal wire. We found it to be quite rugged. There was no worries about bending or breaking it.
Two: you must remove the wheel sets and spread the truck frames apart on both sets of trucks. This will reveal the tabs the hold the shell onto the chassis. Refer to the instructions that come with the loco to do this. Once we had the shell off we put the wheel sets back in place right away.
Photo above shows wheel sets removed and truck frames spread apart. This reveals tabs to remove shell. See next photo to locate tabs to remove the shell.
Photo above shows tabs that hold shell on. Pry outward on the tabs with a small screwdriver to free the tabs and remove the shell. After the shell is off put the wheel sets back together and remove the NMRA shorting plug and the two small jumpers located on the sides of the lighting board.
Photo below shows NMRA shorting plug removed. Also Ditch Light and number board jumpers removed.
It is very easy to hook up the blinking ditch lights and number board lights. No resistors or special wiring needs to be done. Simply attach the function wires to the appropriate tabs and the installation is done.
Photo above shows the T6X decoder installed. Notice the violet pink and brown wires soldered to the tabs on the MTH light board. We used violet for the number board lights. Brown for the left Ditch light. Pink for the right Ditch light. Program the following CV's as follows and you will have complete control of the operating ditch lights and number board lights. Set CV39 and CV40 = 4, CV53= 42, CV54=43, CV52=32, CV36=16. This sets button 3 to operate the number board lights, button one to turn on/off the ditch lights, button two will blink the ditch lights.
Photo above shows the extra wire taped down using 1/4 inch Kapton tape. It is good to keep the installation neat. Tape down the decoder and wire in place. Simply reverse the steps for removing the shell to re-install and you are finished!
Important Soldering Tip
Please do not use any flux either liquid or paste on the mother board. Over time, the acidic properties of liquid or paste flux will begin eating away at the fiberglass PCB and will damage it. Use only Rosin-core solder or no-clean flux approved for electronics use.
TCS recommends the use of Kester "44" Sn63 Pb37, .015" diameter Rosin-core solder. Kester part number 24-6337-0007.
You can order this solder from the following retailers:
Digikey - PN:KE1110-ND
Techni-Tool - PN:488SO6775
Other solder tips
When stripping wire, only strip a tiny little bit of the insulation. Strip no more then a 1/64 of an inch. When the wire gets tinned with solder, the insulation will shrink back more. Try to not expose any more wire then half the length of the solder pad at most. In no case should solder or exposed wire wire ever be outside the boundary of the the solder pad you are attaching a wire to.
Click here for important information on properly Stripping and Tinning wire