TCS Z2 Decoder Installation for the HO-Scale Bachmann Speeder performed by Carl Marchand, Tampa, FL.
Recently I was approached to install a DCC decoder in a Bachmann HO scale speeder. The challenge was intriguing; how to find room for the decoder without placing it on the "control deck", which is the easy way. Could the headlamp be illuminated?
After carefully examining the entire assembly and making a few measurements, I decided the best approach was to slightly modify the control deck by raising it 5.5 scale inches and carving out bits of plastic from the deck to accommodate a TCS Z2 decoder.
Summary of parts:
- TCS Z2 decoder
- Plastruct styrene sheets and strips - .010 in, .060 in (or .020 and .040 strips)
- TCS Sunny White SMD LED( with leads)
- TCS Kapton Tape
- PollyScale SCL Hopper Yellow Paint or similar
- 5 minute Epoxy
- 3M 415 double sided tape (not the foam kind)
- 3M 191CL Repair tape - clear
- SMD (Surface Mount) 1/4 watt or 1/8 watt resistor, 1.5 K ohm
- STEP ONE - Remove the bottom cover
- TIP : break in unit thoroughly before installing any electronics. This gives the motor brushes a chance to "seat" and will polish the wheel contact surfaces for better operation.
Shown before decoder install.
Unscrew the five screws and remove the bottom cover. Mark the bottom of the motor with a dot from a magic marker, preferably black as lower terminal is the negative terminal.
Remove plastic material from top cover as shown.
Add styrene sheet to control deck top.
Removing the plastic material may "blemish" the top side of the cover; to resolve this issue, carefully sand the top side until its flat, then "laminate" it with a sheet of .010 styrene. I made mine from bits of styrene then used Bondo Glazing Putty to fill the seams. Next, paint the entire assembly with SCL Hopper Yellow. Dont worry if the yellow differs from the main assembly; the original deck is slightly different from the overall body color.
Flatten the metal contacts so they will not touch the motor commutator; this isolates the motor from the frame.Attach the decoder input wires to the contacts as marked.
After soldering the wires to the contacts, attach strips of Kapton tape to the areas indicated by the red boxes. Be careful not overlap the tape onto worm gear wells.
Preparing body and top cover; attaching decoder to motor.
Optional - to illuminate the false headlamp, carefully remove the lens by saturating the lens and housing with Walthers Solvaset to loosen the lens glue, then remove by breaking the seam with a Xacto #12 blade (small curved). Drill the housing dead center with a number 61 drill bit. Remove enough plastic from the housing by drilling to accommodate a SMD LED (Surface Mount LED), available from TCS. Use a 1/4 watt SMD 1,500 ohm resistor in series with the WHITE function wire. Coat the resistor with epoxy or similar adhesive to electrically insulate it.
Reassembly - this is probably the trickiest part of the process. Carefully slide the body over the main assembly while keeping TOP control cover tucked inside its walls; do not attach the cover to the frame until the body is attached and the wires from the headlamp are carefully tucked underneath the cover. Take care to keep the wires away from the four cover mounting holes (refer to the photo for positioning).
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