POWER TAPS! The Final Solution to the Voltage Drop Problem, One Way Or Another!

Some time ago I did a post called “AFX vs Tyco: the Platform Question, Revisited.” It was there that I explained that I’ve been struggling with voltage drop problems across my track ever since I built Drag City Mk IV, which is when I switched from Tyco to Tomy AFX. To reiterate: I have frequently had major power issues, especially affecting one lane, but I have usually been able to cure them with cleaning and joint checks. I have also replaced a couple of sections of track which were corroded or, in one case, defective. Over time I’ve traced the cause of this to the “corkscrew” section of the track, which makes sense, as the elevated part of the track obviously puts stress on the connections, but it’s not as cut and dried as that. Even with the aid of a multi-meter I have sometimes found it difficult to find the root cause. The main issue is that every time I think I have it cured, the track is fine for a few days or even a few weeks but it always comes back again, and it seems to move; its usually along the same section of track, but the start and end of it changes, and so does its severity.

Just recently I wrote about my long overdue implementation of a variable DC power supply, and described how bumping up the voltage beyond the anemic power offered by the wall wart made even the slight voltage drop problem I was then seeing become almost undetectable. Well, of course it did; that makes perfect sense. However, it so happens that I decided that the first tournament I wanted to run after installing that new power supply was a race for my Trans Am cars.

As I’ve mentioned, the TA fleet have completely stock chassis, wheels, and tires; the field magnets, traction magnets, and everything else are stock strength and stock position, and so they don’t have the increased traction of the customized cars in my other racing fleets, but due to their low mileage and race-time (to date) they are extremely fast. As a result, they move too fast with the increased power the new power supply offers, even with the variable resistance controllers. The solution was, of course, to lower the voltage. So I did, finding 17V to be ideal, but as soon as I started racing, the voltage drop problem was back…with a vengeance.

The reason I bought the variable DC power supply was to have the flexibility to race with whatever power settings were most appropriate for the cars I was racing and the type of race I was running; simply turning up the power is fine when it works for what I’m doing, but it’s not going to work for every situation.

I’m tired of chasing this problem; I’m tired of taking the track apart, cleaning it, running the meter around it, and curing the problem only to have it return.

Of course I’ve always known what the “final solution” to this problem should be: more power taps.

That goes without saying; my track is a good 50 linear feet, so it should have at least 2 power taps in addition to the terminal section. So yes, that’s obvious. So why I haven’t I just added them? Well there’s a very good reason why: it’s a hell of a lot of work! I’ve been considering it for over a year, and I could think of only 2 ways to do it:

• Solution 1: add 2 additional terminal track sections to the track at different locations; buy 2 additional wall warts and FOUR additional controllers for no purpose other than to destroy them by chopping the wires off for the connectors and throwing the rest away, then soldering ring terminals to the ends of the clipped wires and adding the controller leads to my controller hook-ups and the power supply leads to the terminals on the DC power unit.

• Solution 2: solder jumper wires to the bottoms of both rails of both lanes of at least 2 pieces of track, and run the jumpers through holes drilled in the table back to the terminal track.

Neither is rocket science, but think about the logistics of each solution: for solution one, buying 2 more stock power packs and FOUR more controllers is a lot of stuff just to chop the connectors off of. For solution two: well, are you skilled enough to solder wires to the tiny amount of exposed sections of rail on the underside of these track pieces without the soldering iron melting the plastic track? And can you get those solders to hold well enough that they not only carry current, but don’t break when the time comes to install the track?

Well, I know how to solder well enough, but I don’t have that kind of experience and skill. Fortunately one of my best friends is a former electrician and he does have that skill; so, for a 6-pack of good beer and a steak and potato dinner, he agreed to help me try to implement solution two. I warned him how difficult it was likely to be, but even after seeing all the parts and looking at the situation, he was convinced that we could do the job together in less than two hours.

The poor guy had no idea what he was getting into.

It took an entire Saturday, working from roughly 3:00 in the afternoon until midnight (including a run to Ace Hardware for parts and an hour break for that steak dinner). Having identified the 3 strategically selected pieces of track to install the power taps on, I partially disassembled the track to obtain those pieces. The wire we were using was high quality but very thin speaker wire that was in no way color coded, so since we had to keep the constant and switched rails for each of the lanes straight between each piece, we had to come up with our own color key and use a trio of Sharpies to mark the wires ourselves.

While he worked the soldering iron, I measured and templated and then drilled holes in the table under those track sections. We then attempted to feed all 4 wires hanging off each of the 3 pieces of track through those holes very carefully and gently, in such a way that the track laid flat on the table but the wires, when pulled through the holes, did not break their delicate soldered connections. We had to go back and re-solder the connections on the track multiple times, since the connections either had imperfect continuity or didn’t work at all when we tested them with the meter, or they worked perfectly until we went to install the track pieces and then the connections broke, causing the wires we had fed through the holes so carefully to be “unfed” back up so the track pieces could be taken back to the workbench to try again. In several cases I had to use my Dremel to grind away some additional plastic under the track to expose more the rail in order to get a better solder. After the first couple of times we hit upon the idea of bringing in the hot glue gun to “stick” the soldered wires in place, which helped.

There was no way I could have done this on my own: it was most definitely a 2-man job, especially since one of us had to hold the track over the table and feed the wires down the holes, while the other (me, since I’m the small one) had to be underneath the table taking those fed-through wires and pulling them gently through, then twisting them together with the color keyed wires from the other two pieces and finally capping them with wire nuts.

It was a hell of a job; it was frustrating and difficult, and having to go back and redo the solders over and over again went from tedious to downright infuriating. My friend’s soldering skills, however, were exemplary, in the sense that he never once melted or burned through the plastic of the track. I felt like I owed him a hell of a lot more than dinner and a few beers after all this work, but he was more good-natured than I was about all the difficulty we encountered in doing this.

Right before midnight it was finally done, and it was time to kick the power on and see what we had…

What we had was AWESOME! I took two of most tired, run-down cars I have and ran them on voltage so low that, before, there would be no way they could complete a circuit around the track even at full throttle; they never even slowed down, not once, along the entire length of the circuit: SUCCESS!!!

I tested repeatedly with several cars and at several power settings and at no point could I duplicate the voltage drop that I’ve been seeing on and off for over a year. It was a lot of work, but looks like this problem might finally be solved.

I sure hope so…because after all this work, if this problem rears its head again, I’m afraid that Drag City Mk IV will close down and get bulldozed; I’ll tear the whole thing apart, diorama and all, and I’ll build a new track…going back to the Tyco track I was using before. I never had these power problems with the Tyco track, and with the variable power supply I believe I will be even less likely to encounter an issue.

Hopefully Drag City Mk. V doesn’t have to be built ahead of schedule!