Proto 2000 decoder installs

DCC decoder installations in an ABBA set of HO-scale Proto 2000 F7s for the Greeley Freight Station Museum.

Note that Walthers tooled the gear box covers a bit too large and it can hit the coupler pocket. The backs of the short Kadee couplers must be trimmed to avoid derailments.

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Bob > Proto 2000 F7 after removal of cab and just before ripping out electronics boards to make way for an NCE decoder. The blob wrapped in electrical tape is a cluster of 680 ohm current limiting resistors for the LEDs.

Number board LEDs will be colored with an orange "Sharpie" pen, re-wired in parallel, and receive a 10K dropping resistor (stock is 680 ohm.) The headlight and Mars lights will be replaced with Richmond Controls Sunny White LEDs for a better beam pattern.

Bob > Here is a big problem. Walthers claims ton the box that this is "DCC Ready" but did two things wrong--the NMRA 8-pin socket is missing, and the pads are rotated 90 degrees from other Proto 2000 locomotives. The NCE P2KSR decoder cannot fit sideways as it is too long. At least Walthers retrofitted 680 ohm dropping resistors to keep the LEDs from burning out when powered by DCC.

Bob > Proto 2000 F7B with NCE P2K decoder installed. The P2K plug is sideways and the decoder will not fit without removal of the OEM electronics boards. The decoder is attached to an 0.060 thick styrene plate by foam tape and wires held down with Kapton tape. Longer M2x8 mm mounting screws were purchsed from Small Parts.

Note that the motor wires are color-coded backwards and need to be swapped. Everything is soldered directly to the NMRA 8-pin plug.

Bob > Reworked lighting module. The P2K headlight LEDs were replaced by Richmond Controls Sunny White LEDs. The bodies will be painted black to reduce stray light.

The OEM mess of wires has been reduced from 8 to 4. Number board lights, painted with an orange Sharpie marker, are wired in parallel to a 10K resistor. A single positive common wire eliminates 3 redundant wires.

Warning! P2K did not follow standard NMRA wiring color codes. Blue wires go to the function outputs (negative) not the NMRA blue function common. If you connect blue to blue, the LEDs will be wired backwards and fail to light (or fail altogether!)

Bob > Bottom of the reworked light board, showing the parallel connection of number board lights.

Bob > The installation in this A-unit is complete and ready for weathering and button-up. It was easier to solder wires onto the NMRA plug and insulate with heat shrink than to remove the pins and clean out the pads.

Note that there are two wiring channels cast into the frame below the cab assembly. Be careful to route the wires in the channel and avoid pinching them under the cab.

Proto 2000 F7 after removal of cab and just before ripping out electronics boards to make way for an NCE decoder. The blob wrapped in electrical tape is a cluster of 680 ohm current limiting resistors for the LEDs.

Number board LEDs will be colored with an orange "Sharpie" pen, re-wired in parallel, and receive a 10K dropping resistor (stock is 680 ohm.) The headlight and Mars lights will be replaced with Richmond Controls Sunny White LEDs for a better beam pattern.