Because it has been so slow here on the forums, I’m digging deep into the fairly mundane to find things to share. Here is one project currently on my work bench.
I have an undecorated Overland Alco C425 and a C/P Erie-Lackawanna C424 to get running on the A&O. These are reasonably-detailed engines with the late-1980s low-slung Overland drive. But for some strange reason, both units only pick up power on half the wheels. This doesn’t make for the best operation when the wheels and/or track gets dirty.
Here’s a top view of the front truck. There are wipers only on the left two wheels, and a single wire that went to the motor. The flat wiper is soldered to the side of the truck bolster.
One simple solution came to mind—resistance solder a small piece of double-sided PC board to the other side of the bolster, underneath, and conventional soldering a length of 0.020" phosphor bronze wire as a pickup. Soldering went fairly easy, using no-clean flux and leaded eutectic solder.
The wipers will be tuned during reassembly after painting. If you expand the first photo, the visible wiper barely touches the back of the wheel. That one might just be replaced with matching wire wipers.
Unscrewing the black Overland truck wire revealed a horrible soldering job of the wire to the crimp lug, done with acid flux, that corroded both the joint and even the steel screw that held it into place. It was ready to let go.
This is not an uncommon occurrence on imported brass locomotives. One of the factory wires soldered to the Pittman motor on this engine fell off in my hand, corroded beyond recognition. On a C&LS locomotive, I had to cut back most of the motor brush wire’s length because acid flux used during soldering wicked down underneath the wire insulation, making most of the wire impossible to solder.
Anyway, here we get a new pair of pickup wires. These are 30 AWG stranded wire, very flexible, procured from Pololu.com. Too small of a gauge for O-scale? Not really. These locomotives draw less than 1 Amp from the track at normal speeds. They have Pittman 8413 motors rated at a 3.75A stall current, at 12 Volts.
1 Amp flowing through 1’ of 30 AWG wire drops only 0.1 Volt, so the wire dissipates less than 100 mWatt (half, if both trucks equally pick up current.) Of course the wires, once clipped to service length, will be far shorter.