Got this stupid simple problem I can't seem to fix. I am trying to rewire my athern sw-7 for better pickup and dcc conversion. I am having a problem getting the solder to stay attached to the frame. I have cleaned, smoothed, and fluxed. What am I missing? What has made this one a little harder is that the light pickup thing has come off the frame. Usually I just cut it down a little and solder to it. I need your guys help!!!!
Mike
alco's forever!!!!! Majoring in HO scale Minorig in O scale:)
It will be a lot less frustrating to drill and tap the frame for a 2-56 screw.Then either wrap the wire around the screw or find a small terminal connector. If you want to solder, use a 140 watt iron with flux and rosin core solder. Tin the frame before adding the wire.Then pre-tin the wire and work very quickly making the solder joint.
Second the above. If this is an old Blue Box type loco, the material the frame is made out of probably won't take solder very well no matter how clean you get it. Drill a hole, tap it, and screw in a brass screw and you'll have no problem soldering. Or solder thing flexible wire (like decoder wire) to the one of the rivets on the side of the truck and bypass the kingpin power transfer completely. Do this on both trucks and wire both together as one rail input for the decoder. Solder wires to the two tabs that stick up from the trucks and connect those together to be the other rail input to the decoder. You can solder down near the truck and clip off the rest of those metal pieces to gain more interior room.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Hi,
Years ago (when I had a plethora of Athearn BB locos), I encountered a similar problem. As noted by Randy, the frame is just not conducive to electrical soldering. The best way is to tap a hole and insert a screw with the wire attached. However, at that time I did not have taps, so I drilled a hole, wrapped and soldered the wire to a small cap head screw, put a dab of Walthers Goo in the hole, and pushed the screw inside. Put the frame aside for 24 hours, and then you should be "good to go".
As long as we are on the subject, may I add........ I do not own any Athearn BB locos today - having "upgraded" to Proto, Atlas, Kato, Stewart, P2K, and BLI. But, when I got into HO in the early '60s, those Athearn locos were the only way to go. I seriously doubt I would have stayed with HO through all those years if it was not for those affordable, good running, and great value for the money locos.
ENJOY,
Mobilman44
ENJOY !
Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central
Thanks all for the info. This has the metal frame trucks and I can not get them apart. So I guess I will drill and tap the hole. This will be my project for today as I have 2 to do. Thanks
I'm with BSBrass and Randy. The material is probably a pot metal (high in zinc) and certain metals just aren't conducive for soldering to. I would agree that the best method would be to "mechanically" attach the screw to the frame. And take your time tapping.
To tap a drilled hole:
1. Rotate your tap an 1/8th turn at a time
2. Back it off an 1/8th
3. Rotate the tap back and forth 2 or 3 times to break up the chips.
4. Repeat Steps 1-3 for the next 1/8th turn
For a 2-56 screw, you'll need a #50 or #51 drill bit. Also, use a little lubricant (WD-40) on the tap to help with the chip removal.
Use a tapered tap to start the threads in the hole. Your drilled hole will therefore need to be deep enough for the tapering tap to cut the threads in. When you "feel" the tap start to bind at all - STOP! What you don't want to do is to break the tap off in the hole.
Hope that helps...
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
The Athearn BB diesels all had/have Zamac (zinc alloy) frames. On an easy-soldering scale of 1 - 10, they are about a 16.
If you drill and tap a cleanly-threaded hole, the screw will hold a wire without soldering.
Make sure the normally-grounded brush of the motor is isolated from the locomotive frame. Failing to do this will absolutely, positively fry a decoder.
Chuck (Modeling Central Japan in September, 1964)
tomikawaTT The Athearn BB diesels all had/have Zamac (zinc alloy) frames. On an easy-soldering scale of 1 - 10, they are about a 16. If you drill and tap a cleanly-threaded hole, the screw will hold a wire without soldering. Make sure the normally-grounded brush of the motor is isolated from the locomotive frame. Failing to do this will absolutely, positively fry a decoder. Chuck (Modeling Central Japan in September, 1964)
Thanks for the advise on tapping a hole. I used to work at an ACE hardware store and a machine shop. I have tapped my share of holes in the past but this could be useful info for someone else reading this thread. Thanks again though.
I got the one done today. Drilled the hole and got the screw in and wires hooked up. I changed out the metal couplers as well and put the 2 sw-7 on the track together. They run great. Now all I have to do is the other one and put in the decoders and figure out the lighting issue.
Mike, if you up grade any more old Athearns look at the Digitrax DH163 TA or 123 TA's. All most a solder less install. Mine would not have needed any solder, but after playing with the wires few factory joints failed.
One other thing to check that has bite me in the caboose! Chassis will still be hot, make sure the wires or side frame of the truck cannot contact the chassis! All so make suer the wheels cannot contact the frame. This easy to over look mistake cost me 4 decoders.
If you have any RTR Athearn DC plug In's test the movement of the trucks with it installed.
Cuda Ken
I hate Rust
Thanks ken. I have the digitrax dz125? That I will put in the 2 sw-7's. Room is tight and an ho scale one is way to big for the little space provided. I am trying to keep it out of the cab.
There may very well be a DZ type AT decoder. But check the truck movement regardless of the decoder.
Oh I will. I have run into that problem without the decoder in it. Kinda wierd as I am not sure what they hang up pn. mystery yet to be solved