After about 10 years, maybe a couple more, I’m getting around to putting a decoder in a P2K PA that has never been out of the box. Initial test in DC prior to decoder install demonstrated that it ran great. Question is, should I go ahead and put a drop of Labelle 102 Gear Grease on the worm gears, which are easily accessable now, or do I run the risk of messing up a loco that is working just fine?
Mike
Based on wide experience, best bet is to clean as much of the old grease out as possible and lube with the Labelle. The factory grease tends to harden and may have lost some of its properties even if it still seems to run OK.
BTW, the first run P2K PA’s (single stripe scheme IIRC) were infamous for high amp draw. If so, you may want to ensure the decoder you use can handle that high draw. If it has the motor used in the later runs, should be OK.
Service and lube it while you have it open. I’m doing the same with an Atlas H24-66 Trainmaster.
OK. I should know this, but I’ve never done it. How do you measure amp-draw? I’ve got an old Radio Shack Multi-meter.
Mike
I have a Proto 2000 PA-1 that’s probably as old as yours. It’s amp draw is low enough that I was running it with a Digitrax Z Scale decoder.
The bad ones are really obvious - along the lines of 4 amps stalled. Low running though, so you can be fooled.
To test a draw this high, you have to put your meter in amp mode, which is also usually a different hole to plug the probe in on teh front, common is a 10 amp range, it will be labeled soemthign liek 10A and probably also have a caustion next to it. The meter goes in series with the track power, not parallel like used for voltage measurement. Witht he DC pwoer pack on full speed, hold the flywheel so the motor cannot turn adn read off the current. Don’t hold it for long, it’s not good for any motor to stay stalled regardless of how much current it actually draws.
Definitely slean out and renew the lube while it’s open. I haven’t heardof those having cracked gear issues, but my GP-7’s are all from the cracked gear era so when I put a new one in service I replace the gears as well, no sense putting it all together, installign a decoder and LEDs, and then having to take it apart again in a month or week when the gears crack.
—Randy
If your multimeter has a 1 amp or higher range built in, you wire the meter in series with the power pack, so that all the locomotive current has to flow thru the meter. If the meter pegs out backward, just reverse the meter leads to change the polarity.
If your Radio Shack meter lacks a 1 amp or higher range (best current range on my Radio Shack meter is 600 mA or 0.6 Amps) and you need a higher range, you place a 1 ohm resistor in series with the locomotive, so that all the locomotive current flows thru the resistor. Measure the voltage across the resistor. By Ohm’s law, I = V/R. In the special case of R = 1, Ohm’s law reduces to I = V.
You can make your own 1 ohm resistor if you cannot find one for sale. Get some thin copper wire and a copper wire table that gives you the ohms per foot for your wire. Compute the number of feet needed to equal 1 ohm and wind the wire around a bit of dowel or wooden pencil. You can find copper wire tables on the 'Net or in the CRC handbook of physics and chemistry at your town library.
Old open frame motors in HO can draw as much as 1.5 amps. The newer can motors only pull 0.5 amps or less.
There are three currents of interest, the current to just make the engine start to move, the current with the wheels spinning at 12 VDC, and the current with motor stalled at 12 VDC. Stall current will be the highest, and the conservative model rail will want a decoder rated to handle motor stall current. About the only way to measure stall current is to put your fingers on the armature and hold it still. If this is impractical, settle for using wheel spinning cu