SP 2670 April, 2010 ©2010 Daniel Cortopassi Please do not redistribute without permission. Usage Info   Athearn SW1500, SP 2670   Overview Cosmetic Changes Electronics Review   Overview   This is an old Athearn "blue-box" SW1500 that I have owned for many years. Even though Athearn has since come out with an upgraded version (see my write-up of WP 1502), I had done a lot of detailing on this factory-painted model and wanted to keep it (plus the SP versions of the upgraded locomotive are very hard to get).   photo by Mike Yamada of Makai Graphics   This photo is from 2000 on my old layout. At this point the locomotive was numbered 2632 and was running on DC. Oh, the simple days when installing lights meant gluing MV lenses to the light openings and calling it a day! Back in the 1990s I made my own custom flush-fitting cab windows by cutting each one out of clear styrene sheet and filing them down. I think there is a kit for that now. I also added uncoupling levers, grab irons, MU hoses, custom made handrails, and a few other details. Under the hood I swapped the original motor for a Mashima from A-Line and replaced the wheels with new ones from NWSL.   I did subsequently install a LokSound 3.5 decoder and Miniatronics bulbs in the model, but it was one of my early DCC installs and the wiring was sloppy. There was no cab interior, and the wires and resistors for the cab headlights and gyralites were visible, a real mess. The model also had a problem with wires rubbing on the drivetrain somewhere. This didn't affect the running qualities, but it was noisy and bothersome to me.   Cosmetic Changes   I was unhappy with the weathering on the model. It was too heavy even for the SP and not done as well as I could do it now. I mostly model the early to mid 1990s and in 1995 I had taken a photo of SP 2670 in South San Francisco. I have a preference for modeling locomotives that I have seen in person, plus this one still had its full SP light package at that time.     Originally I thought to simply renumber the locomotive and try to clean off some of the weathering, but this proved impractical. Eventually I decided to strip it down. Since I wanted to preserve as much of the detailing as possible, I did not want to throw the model into chemical stripper. Old Athearn shells are generally safe to immerse in hobby paint strippers, but I wasn't as confident with the detail parts. Instead I used my Badger sandblaster to remove the worst of the weathering and lettering.     I did not remove all of the paint. I have found that often it is enough to just get the lettering off so that it doesn't make bumps under the new paint, especially if the model is going to be repainted in the same color scheme.   Now was the time to do any additional detailing. 2670 had a different type of sand filler hatch on each side at the back of the cab, so I cut off the molded-on parts and replaced them with new ones from Detail Associates. I also took the opportunity to remove the original air reservoirs and replace them with new ones from Details West, along with the associated plumbing and air filter. The Details West air reservoirs are made of metal, which has the added benefit of adding a bit of weight to the locomotive.     SP's SW1500s were not all alike, so when modeling having good reference photos is a must. I ended up remodeling the pilots to more closely match the prototype, removing the beam that ran across the bottom and installing brass parts from Rail Flyer. 2670 also had lost its class lights by the time I took my photo, so I removed those and plated them over with covers from BLMA.     I made my own cab interior insert for this model using bits of Evergreen styrene sheet. The seats and console are from Atlas. So far as I have been able to determine the interior of 2670 was painted either a pale gray or pale tan, so I mixed some Polly Scale Depot Buff with Reefer White and airbrushed the completed assembly. I may do some additional detail work with a brush, and I have some figures from Preiser that I want to use as crewmen. The cab interior is somewhat simplified, but I think it will look fine once it is installed, certainly better than nothing. I did this before I acquired my WP unit, but the design I came up with is very similar to what Athearn is putting in the newer upgraded SW1500s.   Note that there are styrene blocks under the floor. This is so that the floor of the cab will clear the gear tower on the rear truck. This makes the floor about a scale foot too high compared to the prototype, but I don't think the discrepancy will be that apparent on the finished model. The revised Athearn SW1500 cab interior inserts are the done same way (they use the same trucks).     Before painting the exterior colors I re-primed the model with Polly Scale Undercoat Light Gray. Priming is a must under red, yellow, or orange. I also sprayed the interior of the cab with the same color as the cab insert.   I painted the model with Polly Scale SP Lark Dark Gray and a custom red mix. The decals are from Microscale. I have had sheet 87-612 for years, which has the red lettering, and I finally got to use it! The locomotive was not originally painted this way, but some SP locomotives lost the white lettering over time, exposing red beneath.   Note that I left the MU hoses and other pilot details on during painting, since portions of these items should be red anyway. I will get the "rubber" parts of the hoses and other details with a brush later on.     After repainting the model I installed a Cannon walkway tread kit, which I'd prepainted the same color as the model. I did it that way rather than attach it before painting because I thought it would make masking a little easier, though in the end I'm not sure it made that much difference. When this photo was taken I had not yet installed the photo-etched corner steps that are also part of the kit.     I wanted to light up the numberboards on this model. Thankfully the numberboard box assembly was already hollow, so it was just a matter of cutting two openings in the front. I drilled a pair of small holes in the front of the cab behind each numberboard for wires. The sub-miniature sunny white LEDs are the small rectangular objects inside each numberboard in the photo. The gaskets around the windows are a very visible and seldom modeled feature on many SP switchers. I simply drew them on with a metallic silver colored pencil.     After studying photos of SP switchers I noticed that the numbers are mounted behind glass. To simulate this, I applied the decals upside down on the back side of a pair of filed down numberboard inserts from American Model Builders (the kit was designed for cab units, not switchers, but they were almost the right size). The photo is not reversed. This shows the clear numbers before I applied some plain white decal on top of them. When turned over, they read correctly and appear to be mounted under glass.     For me the cab always seems to become one of the most challenging parts of building a switcher. I wanted the full SP light package to work. Between that and the numberboards, that meant five LEDs in the cab roof! The photo shows the completed cab assembly. I used 3mm sunny white LEDs for the headlight and oscillating lights and a 2mm red LED for the red emergency light. The blue common for the headlight and oscillating light were soldered together in the cab roof to make for one less wire coming down into the main switcher body. The blue wire from the red LED had to remain separate, as this light would be operating off of a secondary decoder.   The LEDs are secured inside heat shrink tubing which also connects them to their respective fiber optic strands. The electrical tape helps to hold everything in place and also stop light leaks. I also applied some acrylic artist black paint (a thick-bodied paint) to seal up any remaining light leaks. It took some time to get all of this right, but the results were worth it!   After this photo was taken I painted the black tape a similar color to the rest of the cab interior. From normal viewing angles, all this stuff in the roof is not visible.   Reinstalling my custom-cut window glazing was not as easy as I thought it should have been. I had carefully removed and labeled each piece as to where it went and in what orientation, but when I went to put the pieces back in the windows, they were all too tight. Apparently I added just enough thickness when repainting the model to reduce the size of each window opening slightly. I had to carefully file each piece of glazing again. I used acrylic gloss medium as an adhesive, applying a little bead around the inside of the window opening before inserting the glazing.     This shows the inside of the hood after the cab was reattached and all wiring completed. I reused the LokSound 3.5 decoder that had been in this model before, and it is mounted in the center above the motor. A TCS FL-4 is mounted near the cab (under the black tape), and this decoder is in charge of the numberboards and red emergency lights. I did it this way since I needed a total of seven functions, more than are available from any sound decoder I know of, so no matter what it was going to take a second decoder to accomplish all that. The LokSound had always done a good job running the model, too. The speaker is a LokSound 16x25 mm mounted in a custom made enclosure. The fiber optic strands for the headlights run through this enclosure. The blue stuff is RTV silicone sealant to keep the enclosure airtight. This is a good little speaker, with plenty of volume despite its size.   One of the things that can be a problem in any engine is loose wires. It's important to keep wires from rubbing on parts of the drivetrain and away from the face of any speakers. Both can cause unwanted noise from rubbing and rattling. To that end, I electrically connected the trucks front and back with a wire threaded along the bottom of the frame on each side. Then I connected the red and black wires that power both decoders to the trucks, routing the wires around the sides of the motor. The shell is indented on the inside around the motor area, so there was just enough room to make this work. This keeps the wiring relatively neat inside the shell, and also bypasses reliance on friction contacts for power.     It's alive! Not quite done yet, but the switcher is now running again under its own power. When doing an install like this it's important to check things as you go. I tested each light as I installed it and wired it up. You don't want to get to this point and get a nasty surprise by finding out something is wrong that will require a complete disassembly to fix. Taking this thing apart is not something I want to have to do - ever!     Electronics   I had originally thought about replacing the LokSound 3.5 decoder with one of the new LokSound Select decoders, but at the time I was ready to reinstall the decoder the Select was not available with the appropriate sound set. The Select has six light functions vs. four in the 3.5, but I needed seven so that meant using a second decoder anyway. Since I was happy with the performance of the 3.5, I decided to keep it. I used a TCS FL-4 Fleet Lighter for the extra light functions.   I originally had a LokSound twin 13mm speaker pair installed under the radiator area, and I tried to use it again but it was too long and rubbed on the forward flywheel. I don't know how I got away with using it the first time around! I ended up swapping the twin 13 mm speaker assembly for a 16x25 mm speaker from one of my SD40-2s, which has more room inside for a longer speaker.     Review   The lights work well and the locomotive runs pretty well, though it still has a bit of vibration in the drivetrain that I haven't yet figured out. I think it is in the driveshafts, so I may experiment with the couplings between the flywheels and the trucks. Electrical pickup has been good so far, with no stalling, though I have not run the engine enough yet to really give it a workout.

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