This discussion about the AT harness is interesting. Over the weekend I fitted decoders to two BB locos. For the first I used an AT harness and found a few problems. The new motor clips fouled the flywheel where the wire is soldered so needed to be reshaped. The wire was soldered so that it left in line with the motor axis rather than out to the side. Most of the wires were too long to get a neat install. In the end I ended up shortening most of the wires and soldering direct to the loco. I used an AT for the second install as well but hard wired, although I did use the motor clips and plastic motor blocks. If I do another BB install I will simply use a plain harness rather than bothering with the AT harness.
Here is how I wired up a Athearn SD40-2. It was a little newer, had the hex driveline and factory nickel-silver wheels. On the SD40-2 there is room to solder the black wire to the proper part of the truck. The frame is still hot, but I mount the Kadee couplers in an insulated box. To make the frame not hot would take a bit of work, as the pivot bearing area is there as well. If you just added some fiber-plastic shim, the height would be off.
On the newer RTR Athearns, at very least I would take the motor out, and add a layer or two of electrical tape. From the factory they rely on paint to keep things insulated. Some of the boards have been failing, you take your chances. If you decide to hard-wire, remember that Athearn uses 1.5 volt bulbs, so you would have to add resistors somewhere. The Genesis board had LM317T voltage regulators on it for running the lights.
I like the TCS Back-EMF decoders in Athearn engines. Put it on step one, and it starts to move, no adjustments needed.
Mike WSOR engineer | HO scale since 1988 | Visit our club www.WCGandyDancers.com
davidmbedard2. Place ALL the gears in a tupper ware container (with lid) with soap and water. Shake to clean the gears. Drain and dry the gears. Buy a high quality plastic-compatible lubricant and apply it to the gears and gear studs. Re-assemble. At this point, replace the Athearn wheels with NWSL, Proto or Jay-bee half axles. Test for free-rolling ability, they should roll much better now.
Well David, that is the one step I have never done, I have known about it but been to, well lazy.
davidmbedard 2. The frame is live and if you are using metal couplers, you run the risk of a short if you run your locos back to back.
2. The frame is live and if you are using metal couplers, you run the risk of a short if you run your locos back to back.
David, with soldering the wires to the trucks the frame is still hot right? When you do your conversions do you leave frame hot or make them cold? I think part of my problem has been wheels hitting the hot frame while cleaning.
davidmbedardAt this point, replace the Athearn wheels with NWSL, Proto or Jay-bee half axles.
Is the reason to replaces the wheels just because they stay cleaner? I have a Heavy Weight Athearn F-7 I am wanting to take a crack at again. It has nickel wheels all ready.
On the RTR Athearns, would you remove the board and hard wire, if so why?
Your friend Ken
I hate Rust
Kalmbach has a good book on DCC, available at your LHS, which has a chapter on installing a decoder in a blue box Athearn with pics etc. Just get the Digitrax harness mentioned above and follow along. ANY decoder that fits the 9 pin harness will work fine. I'd try a TCS one.
Check stall speed amps w/meter on straight DC. Get decoder that will handle load. I have 2 athearn locos, F7/9, SW1200. My dad is the eletronics guy I go to for questions. Used DH123 in both.They were hardwired. Make sure motor is isolated from frame. Loco's are 35+ yrs. old. Those old motors pull alot amps.1 amp is'nt big enough for these old motors. I made the mistake of trying to clean the wheels by spinning on napkin(SW1200).and blew decoder. Stall amps will kill a decoder. Now I only clean wheels (F7/9) by hand. (hate brass wheels). When clean, it runs smooth as silk. Dane
So as I understand it the second way has seven steps and produces a very acceptable solution. Hardly rocket science in my opinion and I still say easily done by anyone who wants to give it a try.
Chris, you be better sereved asking this question in the DCC section. First thing that comes to mind is how much power does the BB draw. Some of the old motors will draw a lot power will eat a decoder even when installed right. Ask me how I know?
Cuda Ken
I don't think it is hard at all. If you are anywhere near mechanically inclined it should not be a problem. So in a highly unlikely first case scenario he blows a decoder the first time and learns a very valuable lesson that serves him well and saves him a lot of money in the future on other installations. To me its like saying you have a flat tire. You better call somebody who knows what they are doing to change that when the instructions are in the owners manual. There are numerous web sites that explain how to do a Blue Box in detail with pictures. Have at it.
ATHEARN (not atheran) older blue box kits use the frame as a ground, and a fair amount of work is needed to make it DCC. Not the kind of job for a novice. My
Kon
Modelling the BN 1970-1995
The loco is not dcc ready ,it is a blue box kit , is a sd40-2. if any knows thank you. Chris