ZW-R Throttles intermittant

Sounds to me like you need new carbon rollers.  Not an easy job but once you get the case open you might just as well replace all four of them,.  I quit trying to do close work like that, myself, and usually have one of my younger friends do it.

Paul Fischer

Take a good look at the terminal posts in the back. They become worn and could cause an intermittent power issue.

Photos of what you have with the cover off the ZW would help.

I would first check the carbon rollers and internal wiring for obvious defects.

Thanks for your replies...I'll post some pictures tomorrow.

I'll go ahead and do a thorough cleaning of the contact rollers with electrical contact spray first to see if that improves anything. The transformer (right-hand throttle) was working fine until this week. The left throttle already exhibited the intermittent connection when I pulled the ZW from storage last Fall.

One risky way to tell if the problem is your A thru D or U terminals is: when the intermittent condition next occurs (need to have a minute or so of running time), turn all throttles off, then feel the terminals - if they are hot, that's indicating a high resistance/loose connection. Be Careful! They can easily get hot enough to burn fingers!!!

It sounds like the problem is with the "U" bus strip coming loose from the binding posts.

Found the smoking gun! 

I took the cover off and ran the train to put a load on the transformer which caused the carbon roller to arc as I moved the throttle. It was arcing between the roller at the rivet and the contact arm that supports the roller. This occurred on both U-A and U-D throttles. No change after I washed off the rollers with contact cleaner.

I bought this used 30 years ago so no telling how many hours of run time it had before I got it. It looks like it's time to get the ZW serviced with new rollers at the minimum. I have a hate relationship with rivets so I'll need to find someone who can overhaul the ZW.

As promised, attached are 3 photos. 

Thanks to all for sharing your collective knowledge and experience. This is a great forum to keep these antiques running!

Roger

Roger:  Do it soon because once those rollers wear down, that little "U" shaped frame on the end of the spring will start to contact the transformer windings themselves.  Not too long after that and you can trash the whole unit.

Paul Fischer

Thanks Paul, good advice! I'm about to ship it off to Henning's as the other source I'm aware of is heavily backlogged with work.

Roger