So I have been having electrical problems with only my RR 2-6-6-6. I cleaned the wheels and readjusted the bronze phosphor pickups the pickups wipe the axles. Connections to decoder seem good. And there’s a total of 17 pickups/wipers! Yet electrical conductivity is poor.
I’m positive it’s the pickups as I don’t have any issues with the rest of my fleet. But I for the life of me can’t figure out what’s wrong.
Would electrical grease on the axles help?
That’s not the only thing not working.
[(-D]
Don, could it be the plug from the tender to the locomotive not seated correctly?
Regards, Chris
Don’t see how it could make it worse, [swg]
I’ve had success with CRC Electrical Silicone Lubricant.
Terry
have you tried using an Ohm meter to measure the conductivity between each set of wheels and the corresponding connection on the decoder?
work you way up and down the chain to isolate where there is no connectivity. is there connectivity between the wheels and pickups, between the pickups and decoder?
Contact between wheels and the wipers is intermittent at best. Jiggling the wheels side to side sometimes causes a complete circuit signal. Dielectric Greese didn’t help much. Socket is fine. I can see the lights go out for the firebox which is directly connected to the wheel picksups (bypassing decoder)
I think the problem is the wheels have their platting worn off. So conduction isn’t that good. I don’t think a keep alive would help much because the conduction IS so poor. I’m going to see if RR can get me replacements.
i hadn’t heard of dielectric grease before. i’ve seen it used in car light sockets to prevent corrosion i read that it’s non-conductive and therefore think this is not a good application for it because these are moving contacts and any grease that gets between the wiper and wheel will impede connectivity.
If anything, i think a conductive grease would be better as it would impede corrosion between use but may accumulate dirt
i thought a metal wiper is self cleaning simply because it is constantly rubbing the surface.
have you tried cleaning the surfaces with alchohol?
I’m guessing “RR” is “Rivarossi”? Anyway, if the wheels are worn you certainly could try replacing them. Rivarossi has changed hands many times so not sure if whoever owns them now would have parts, but I’m sure it wouldn’t be that hard to find the same size / type of wheels.
BTW have you looked in the tender? It could be the wire connecting the truck pickups has come unsoldered or something.
I cleaned out the journals, axles, and pickups using 70% alchohol. It’s running better. I think it’s close enough now that a keep alive will do the job from here on out. The journals were thilthy with greese. Not sure how that happened. I’m sure some Atlas conducta lube will help. Also solved a problem with it stopping on the turnouts. Turns out the rear firebox truck had a metal arm that was too low and touching the opposing polatiry points causing a short.
It could make it worse indeed if the grease had any tendency to lift the wiper away from solid conduction contact.
Remember that the only ‘conductive’ grease is heavily loaded with silver or other conductive particles, and is both expensive and rare. As with other effective lubricants the material is dielectric, and works only be excluding oxygen from what is fundamentally, at best, little more than a line contact between the face of the wiper and the curved axle.
Only adjusting the actual tension of the wiper on its ‘contact patch’ will help with good conduction. You could wrap the contact around the axle circumference; you could also simulate commutator effect by using a graphite contact button soldered to the wiper and machined to a semicylindrical profile, but these tend to increase drag. They only work on ‘half’ the conductive path if you have all the wheels insulated the same way, so you’d need an approximately equal number of axles in insulated truck journals for ‘hot’ and ‘ground’ (with the pickups appropriately connected to buses in the chassis) to be sure you’re getting solid connection to rail contact on ‘both sides’.
If you can, get a small multimeter and read voltage or continuity as you push the unmotored but weighted chassis around. That will confirm if it’s a contact problem. Then repeat reading voltage across peak load, to ensure the connections can carry sufficient current.
Are your contacts home made? In my experience, I’ve found home made axil or wheel wipers to make intermittent contact, until you tension up the contact so much that it causes noticeable drag. I’ve tried brass wire, steel wire, and brass plate. It’s hard to adjust the tension to the happy medium. Factory made contacts with some sort of real spring work much better.
Now i use homemade contacts only for non-essential contacts, and use a capacitor to carry over during gaps. For example, my caboose lighting has a rectifier, resistor to limit charge current, and capacitor. On steam engines, I’ve added extra (redundant) pickups on tender and engine trailing trucks. I’m in process of adding keep-alive caps to remaining DCC locos, and will install these circuits on any new conversion.
Remember that the best thing to do is to keep your track and wheels clean.
I have had several locomotives that have bronze pickups to the back of the driving wheels or tender axles develop flaky pickup. The pickups and wheel components can get deposits just like the rail-wheel contact. I found that something like WD-40 Electrical Contact Cleaner (NOT regular WD-40!!) works well, better than isopropyl. I spray a bit into a plastic tub, then use a microbrush to rub the cleaner between the pickup and the wheel or axles.