Mar 31, 2008

Keller OnBoard and headlights

So, here I am, sitting at home and quietly finishing up super-detailing my 7 locomotive shells that I've been working on the past few weeks. Yesterday I finished up the last of the tiny decals I like to add - fuel & water labels, warnings, other little tidbits. I'm been using using diesel decals sets from Rail Graphics, purchased quite a few years ago - the last time I did this work, about 1991 believe it or not.

I also re-numbered one of the Athearn PA units (why must all PA-1 units out there be numbered 6009 !?), and finished up add numbers to the number boards of my Athearn PA and a pair of F7As. Not fun, but I did enjoy learning how to do it.

I suppose I should photograph these models when they're complete so you can see what I've been doing.

Anyway, back to Keller Onboard... I switch my focus to electronics, starting with the Lifelike Proto2000 PA / PB pair, which I thought would be the easiest. I had purchased a number of the 8-pin 2x4 NMRA plugs a while back, and soldered up just the track & motor connections on one of them, and plugged it into the NMRA plug on the PA to test it. The motor ran nicely w/ Keller, but no lights.

Of course - I hadn't jumpered the headlight connections. But, after some more experimenting, I found that the two headlight circuits are both polarity-sensitive (pins 6-7 for the oscillating headlight, and 3-7 for the lower headlight & numberboards). The oscillating headlight varies two circuits, to light two filaments inside one bulb to get the oscillating effect - about +/- 5v going to the bulb, but working on with pin 7 positive and 6 negative (I think - I might have it backwards). The lower headlight is just 1.5v, and again works w/ only one polarity.

With DCC, the decoder would provide the correct voltage and power to control these separately, and with normal DC both work but only when the locomotive's moving forward. The problem for me is that the rails will have a set DC polarity, regardless of which way the locomotive is moving. Thus, if the locomotive is on the rails facing west the headlights would work, but facing east they'd be off, regardless of whether it was moving or not.

I could replace both with my golden-white LEDs from NCE, and probably will I guess. I like the oscillating effect, but it uses the locomotives electronics and needs that certain polarity. I could light that bulb directly from track power (skip the electronics), and use a resistor to get down to 5v or so. No oscillating, but easier wiring. Or, I could replace both bulbs with the LEDs wired back-to-back, so that one LED would work for each direction the loco's facing.

I did finally figure out how to address the reverse-voltage problem... those LEDs don't like reverse voltage, and the Keller Onboard system puts 14.5v on the tracks. Turns out that with the LEDs back-to-back, one will light and the other won't, and the dark LED is protected from the reverse voltage by the current running thru the LED that does light. Assuming a current of 30 mA, I'll use a 3660 ohm resistor on one side of the two wires running to the LEDs. This is what I plan to use w/ the other locos.

What to do w/ the LifeLike unit? Not sure yet... I'm leaning now toward just lighting the two bulbs directly with appropriate resistors, if I can guess what their current draw is.

Mar 11, 2008

In a detailing mood...

I've been staying out of the basement lately, and have gotten into a super-detailing mood with some of my diesel locos. It started because I'd reached a point in layout construction where I wanted to install my command-control system (an old Keller OnBoard system). I've started working on that, but got to the point where I needed to install decoders (Keller calls them throttles) in some locos.

Not wanting to tackle the steamers yet, I figured I'd ease back into this by starting with some diesels (remember - my RGS is set in the late 1950s, and the SP has purchased rights or perhaps the entire road, so SP diesels will be showing up sometimes).

Keller likes low-amperage motors, and needs really great pickup in order to work smoothly. On my old layout, I'd converted a pair of GP35s and a pair of SW1200s, remotoring with Sagami can motors (I like the 2032 best), and wiring the units together in pairs, using all 4 trucks for pickups. I also replaced all the old Athearn wheels with NWSL wheels, again, for better pickup (the NWSL wheels are nickel-silver, and much better than the old style Athearn sintered iron or steel wheels).

Those engines will run great, and I next remotored my first Athearn loco, an F7 I received in the late 1970s I suppose. Then, I started on converting a pair of Athearn SP Daylight PA-1s. That project was put on hold about 14 years ago when kids came along, and have sat (in pieces) since then.

Fast-forward to today. I pulled out the ancient F7, and (for practice mostly) got that running again, It also has a Sagami 2032 can motor, hard wiring to both sides of the trucks, new wheels, etc. It needed a drive shaft repaired, and now runs like a top. With a little confidence now, I finished remotoring both PA-1s and two more F7-As, and installed new wheels and trucks on a pair of F7-Bs as well.

So now I'm ready to install the Keller throttles, right? Well, I also have a Proto2k PA-1 that's gorgeous, and really those Athearn shells could use some details. I'm going to use LEDs for the headlights, which means the shells will be hard-wired to the frames, which means any shell detailing is best done now.

Off I went to the hobby shop, and returned with MV lens, handrails, etc. I can't tell you how much fun it was to sit at the workbench installing lift rings, grab irons, and what not. It's been YEARS since I'd done anything like that, and it was very fun to return to. Plus, the basement is still cold and the workbench is upstairs in the comfy warm study. I'm sick of winter, and the warm study is inviting.

I'm still finishing up the super-detailing, and even added a backup light and cab room grabs to the Proto2k unit. I've got the LEDs ready, and will someday get the Keller throttles installed. That's gotta be last, because as soon as they're ready, I'll probably jump back down to the basement so I can get the Keller system installed, and then I might never return to the workbench and finish the detailing work!