303 447-9251 Fax: 303 447-1406 Sales@UlrichModels.com Introduction MTH SD70ACe DCC Ready Soundtraxx AT-1000 EMD 710 Sound Decoder Install Revised June 1, 2011 The MTH DCC Ready SD70ACe has very little room to install a sound decoder and have it not hit the shell. Most quality sound decoders will not fit including the TSU-1000 Soundtraxx decoder. However, by building a small wire harness the Soundtraxx AT-1000 decoder can be installed in the MTH DCC ready SD70ACe. The Soundtraxx EMD 710 decoder gives the SD70ACe quality sound and smooth operation. With two 1 Soundtraxx speakers properly installed in the tank enclosures, and the equalizer set to a value of 2, the sound is awesome. The decoder has 16 resident horns. The Nathan K5LA is usually selected. At the present time Soundtraxx does not offer the SD70ACe sound in any decoder but the TSU-1000. I believe this may change in the future. The EMD 710 sound is a great sound but the starter is not correct for the Ace. Still, until the ACe sound is offered in the AT decoder, it is a high quality sound for the MTH DCC ready model. The installation is very tight and the position and orientation of the decoder is critical. Also a small modification needs to be made to the radiator insert at the rear of the shell for the decoder to fit and allow the shell to go down. When the install is complete, the result is perhaps the best SD70ACe on the HO Rails with the exception of the Overland SD70ACe that cost near $1000.00. The MTH ACe with the Soundtraxx decoder has great sound, is fully DCC compatible, has LED lighting, lighted number boards, metal handrails and is very heavy resulting in superior pulling power. Figure 1 Soundtraxx AT-1000 installed The general procedure to install the decoder is to build a wire harness that connects the power, motor, headlight, backup light and common female pins in the 8-pin socket to the proper tabs on the AT board. Wires must also be connected between the MTH ditch light tabs and Soundtraxx Functions 5 and 6. The wires between the MTH 8-pin socket and the AT decoder are soldered into the 8-pin socket as there is not enough room to use an 8-pin connector and have shell clear the decoder and seat properly. Two 1 speakers are installed in parallel in the tank enclosure. Page 1 of 7
Shell Removal The MTH SD70Ace Shell is not a lot of fun to remove but it can be done without too much stress. Check the MTH Engineers Guide for instructions. It is possible to remove the shell without disassembling the trucks by using a small screw driver through the truck assembly to unsnap the tabs. Once a tab is unsnapped wedge something like a toothpick between the frame and the shell to keep the tab from snapping back in place. Speaker Installation There is a clasp at each end of the fuel tank that releases the halves of the fuel tank assembly. They can be released easily using something like the point of a hobby knife. Figure 2 shows how to wire the speakers in parallel. Use red and black wire and attach the red wire to the same terminal on each speaker. We supply Soundtraxx speakers and one terminal of the speaker is marked with red; attach a red wire to the red terminal on both speakers. Attach the black wire to the other terminal. Figure 2 Parallel Speaker Wiring The speakers are then installed into the enclosures using 1 gaskets. The speaker enclosure covers are set on top of the enclosures with the wires run through the holes provided. The lids do not seal well and are prone to vibrating so they should be attached with a spot or two of adhesive like E6000 or Goop. These adhesives will seal the lid but will allow the lid to be removed if necessary. The wires are run up through the openings near the flywheel as shown in Figure 3. When the speakers are connected to the decoder, the two reds are connected together and the two blacks are connected together. Page 2 of 7
Figure 3 Speaker Wiring, Speakers Installed in Tank. Decoder Install Figure 4 Close-Up View of Decoder Installed The Soundtraxx AT decoder is installed by connecting the decoder to the 8-pin DCC socket and the ditch light tabs on the MTH board. The decoder is connected using wires that are soldered to the MTH DCC connector since there is not sufficient room to use a NRMA 8-pin plug. Page 3 of 7
Figure 5 Wiring Solder color coded 30 gauge wire to the 8-pin connector as listed below. All wire lengths are 1.5 unless noted. Strip and tin one end of the each wire. The remaining end will be shortened and tinned later. Orange Pin 1 3.5 Gray Pin 5 3.5 Yellow Pin 2 3.5 White Pin 6 None Pin 3 Blue Pin 7 Black Pin 4 Red Pin 8 Ditch Tab 1 Green 3.5 (It does not matter which tab is which color) Ditch Tab 2 Purple 3.5 Figure 6 - NMRA 8-Pin Plug Page 4 of 7
After soldering the wires, cover the 8-pin plug with a piece of Kapton insulating tape. Next attach two pieces of 3M double sided tape to the MTH board as shown. Then press the decoder into place. Figure 7 Double Sided Tape Placement Figure 8 Decoder Installed and Wires Soldered Once the decoder is in place, the wires can, cut to length, tinned and soldered as follows: Orange +M Motor Gray -M Motor Yellow Backup Light White Headlight Blue Common Tab Black Left Power Red Right Power Purple Ditch Light Tab 1 Green Ditch Light Tab 2 Red Speaker Wires + Speaker Black Speaker Wires - Speaker Once all the soldering is complete, use a piece of Kapton tape over the board and taped to the frame on both sides to add to the mounting security. Page 5 of 7
Route the speaker wires as shown and then tape them to the frame with Kapton Tape. Figure 9 - AT Board Diagram Now it is time to test the locomotive on the track. See Appendix 1 for information on CV programming. Reassembly The two front tabs on the radiator cover must be removed. The cover will fit snugly with the tabs removed. It is held by tabs in the back and friction in the front. It is unfortunate to have to make this modification but there is very little room in this model and the tabs hit the decoder board. Figure 5 Radiator Cover Next put the shell back on; it is quite difficult to do. To get the front of the shell down where the cab is, there are extrusions the must be aligned properly to slide into the frame section. The tabs on the shell must also be aligned. The shell will go down though. I think everybody ought to write to MTH and ask them what the heck they were thinking when they designed the DCC ready model. It is a nice model but the lack of space is just ridiculous. Page 6 of 7
Appendix 1 Soundtraxx CV Programming Notes Note: Soundtraxx decoders require a program track booster to be programmed and read on the program track. They will program in Ops mode on the mainline. Important CVs CV 2 Start Voltage Set 0-255 to make the locomotive start at a lower speed setting if it is not moving at speed step 1 CV 8 Set to 8 to reset decoder to factory defaults Sound CV 115 Engine Exhaust Control - add 32 to the existing contents to have the sound start at speed step 1 instead of track power. The lower 4 bits of this CV contain the notch rate for diesels. The default is 7; therefore 39 is the default value plus changing the sound to start at speed step one. Generally 32 + (0-15) automatic notch value determines the value for this CV. A notch value of zero sets manual notching that is controlled by F9 and F10. Pressing Emergency stop while the locomotive is stopped shuts the engine down. Bits 6 and 7 are overrides for the dynamic brake are not usually set. See the Diesel Programming Guide for more information. CV 128 Master Volume 0-255 CV 115 Air Horn Select Varies depending on the decoder. See chart that came with decoder. CV 153 Sound Equalizer Default is 0 which is flat. Set to values 1-3 as follows 0=flat, 1 = Tiny speaker under 1, 2 = Small Speaker 1, 3 = Medium Speaker 2-4 or two 1 Speakers. Lighting Features - Alternating Ditch Lights FX5 CV51 = 169 - Type 1 Ditch Light, Crossing Logic, Phase 1, LED FX6 CV52 = 185 Type 1 Ditch Light, Crossing Logic, Phase 2, LED Lighting Feature - Steady Ditch Lights FX5 CV51 = 129 FX6 CV52 = 129 Dimmable Light LED Dimmable Light LED Map Ditch Lights to F5 CV 39=6 FX5 and FX 6 on/off CV40=0 or other desired function Page 7 of 7