My BLI USRA Mikado refuses to go past my Walthers/Shinohara, HO, code 83, DCC friendly turnouts. The Digitrax Zephyr shows a short circuit. I have a Bachman Pacific that hesitates, but goes through OK. My low cost IHC Mogul goes throgh forwards, backwards, slow or fast. The frogs have not been altered either. The same thing happens with #4's Wyes and curved turnouts.
What could be causing the short and what can I do to fix it?
Bruce in the Peg
73
Last I heard, and a year ago when I sent in my Niagara, it is/was 8 weeks.
Bruce, the problem, if I have the correct one, is that the wheels, either driver, truck, or tender truck, are actually touching both rails past the frog, not the closure/points rail side of the frog. Even though it is a gapped frog, per the meaning of DCC-friendly, the angle of departure past the frog, or the angle of diversion, is not the same on each side...at least, that is what my eyes tell me, and it is always on the far side of the frog that I find my double-contact issues.
You can paint clear nail lacquer on each frog rail for about 1/2" past the black insulating insert. It will lift the wheels off the rails and prevent any power at all from reaching them until they are past the paint and back to clear metal. By then, though, the frog rails will have diverged another 1/8" or so, enough to keep the wheels from bridging.
The paint will wear, and you will eventually get another short and have to re-apply. I got fed up and simply used a cut-off to cut one of the rails right through about 1/2" out from the plastic black gapping insert, or where the lacquer layer ended.
If Selector's diagnosis is true (sounds likely to me), there's a possible solution that's more work, but also more permanent. If the nail laquer works, then when it wears off, try this:
Check the clearance through the guard rail with an NMRA gauge -- if it's too wide, try a snall piece of styrene (.010 or so) as a shim on the inside of the guard rail. That might hold the wheelset away from the frog just far enough to prevent a short.
You do have to be careful not to shim too much, or other wheelsets might bind or even stick in the gap.
I have disconnected the Zephyr and connected a digital ohm meter to the rails. As I manually pugh the Mike through the turnout, I can see "where" and "when" the short happens but it is very erratic. I can't tell "what" is causing the short. I have my trusty NMRA standards gauge and will try to see if there is somthing amiss with the turnouts. In the meantime, does anybody have experience with these Mikes? Does the power from the rails come from the engine alone or is one side from the tender?
AFIK, the BLI steamers, all of them, have full pickups on all drivers and on at least two axles on each truck of the tender. That is a lot of pickups, but I'm willing to put some serious cash on the table between us to bet that the problem is at the meeting point of the frog rails. Not inwards of the insulating bands that are inset about 1/4" from the point, but as soon as the problem axle(s) pass over it and onto newly powered rail. The Pecos are the same, by the way.
I suppose it is possible that BLI assembled the tender axles backwards, but that would mean you'd get the short as soon as you powered up the layout...wherever the loco was sitting. Since it moves successfully onto the points (right?), that is not the case, and I am sure you experience the short after at least one set of drivers has moved past the frog point.
Am I wrong?
Blind Bruce wrote:>>> snip <<<< In the meantime, does anybody have experience with these Mikes? Does the power from the rails come from the engine alone or is one side from the tender?Bruce in the Peg
>>> snip <<<< In the meantime, does anybody have experience with these Mikes? Does the power from the rails come from the engine alone or is one side from the tender?
Yes, I have two of them. All loco drive wheels are powered, and each tender truck picks up from one rail.
On a piece of straight and level track, you can confirm this (ease the tender clear off the rails, then the engine, then lean the engine one way and the tender the other, then vice-versa).
If it isn't powered during all this, there's something mechnical wrong, like a loose or broken wire (check the cable and plug between engine and tender), or the like; or some very dirty wheels and/or track.
But again, from your initial description, if you're getting a short-circuit, the problem isn't a loss of pickup. It's too much pickup: something touching something else that it shouldn't.
If you run the engine slowly through the turnout, in a darkened room, you might be able to see a spark when the short occurs. That will be a large clue! The fix will depend on which wheelset it is, and where on the turnout it occurs.
Bruce,
It could be a problem with your W/S turnout. It also might be a problem with you locomotive. If you flip your tender over, you'll notice that the tender trucks/pickups are held in place by a screw mounted spring. You need to make sure that your axle pickups on your tender are tight enough.
I started having a similar problem with my BLI Mike going through an Altas Snap turnout about a year ago. It turned out that the screw that held the copper pickup against the rear tender axle was too loose and that allowed enough slop for the truck to short out on the frog.
Test procedure
Disconnect the tender from your locomotive. With your DCC system ON, push either one of them across the troublesome turnout to see if you can't replicate the short. If it only happens with the tender, determine whether it's the front or the back truck then try tightening the truck screw to see if that eliminates the problem. I think I tightened mine all the way down then backed it off ~2-3 full rotations. Haven't had a shorting problem with it since.
Bruce, keep us posted...
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
Two things occur to me. One is that the longer wheelbase of the 8-drivered Mike will have some wheels perhaps drifting over to the oppositely polarized rails, but that happens with blind drivers, such as on the BLI PRR TI and the various 2-10-4 models. I have not looked at the Mikes, but don't believe they have blind drivers.
Also, I have not learned what frog number we are dealing with. The smaller frog number means more diversion, so the problem I was describing earlier may not apply to those turnouts that diverge quickly. In any event, please see my email.