ZW Roller Replacement

I'll pass on one tip that was given to me.  It saves a lot of work and aggravation if you can avoid disassembling the shafting between roller bracket and lever.  To help in this goal, rather than trying to flatten the rivet head, place a tiny drop of solder.  I haven't had a chance to try this, but it sounds reasonable.  To remove a roller, try crushing it with a pliers (catching the crumbs), and then simply clip the rivet in the middle.

ok thanks any instructions on replacing the rectifier?

Sorry.  No.  It has been, literally, decades since I've done such a rectifier replacement and so I do not recall how I did it.  I presently run DCS, and therefore only use my ZWs to provide power, not for actual operation, so I never use the whistle or directional control.

Trainman 51

Jim Barrett in the Backshop,Volume One Video covers how to replace worn ZW Transformer Rollers and Power Cords[plus several other projects].

Barrett in the Backshop, Volume Two Video covers replacing ZW whistle Diodes* and damaged Hot and "U" Binding Posts[ plus other segments].

I have had these tapes for quite a few years ---I believe they are now available from OGR as the more durable DVDS. 

*rectifiers. Can replace with anode-to-case stud diodes, 40 amp 600 volt, from ALL Electric--catalog #1n1190AR.

Hi being new to the site How do I download them?

OGR sells the "how-to" DVDs. Click on the OGR web store at the top of the page.

Also use "Search" [free] also clickable at the top of the page. Type the subject you seek and go from there. 

I haven't searched lately, but there were some instructional vids on YouTube at one time.

trainman51,

Dewey's list of, Backshop DVD's by Jim Barrett is correct. Rich Melvin posted a message last week stating that all of the Backshop DVD's will become available on amazon.com soon. If you can, purchase the entire series as the need arises. Rumor was, Jim Barrett was to make a few more. I have not heard anything in sometime.

God Bless,

"Pappy" 

The last DVD I have is Backshop #11 which includes illustration HOW-TOs on installing a Lift Bridge and on installing a hinged Drop Section[in a curve].

I still have my original Drop Section recycled from large dismantled layouts, now in use on my little attic layout.  I built it from a long ago OGR Magazine article by Jim and upgraded it based on his DVD #11.

I've replaced the rollers in a number of ZW transformers, and I've never pulled them apart any farther than taking the top cover off.

I gently pull the arm out and tie it about 3/4" from the windings and work on it there.  I can change all the rollers in about 15-20 minutes, very easy job.

To remove the old roller, just crush it with needle-nose pliers.  I've noted that the factory rivets are pretty hard stuff, so I use a Dremel cutoff wheel to cut them instead of trying to clip them with wire cutters.

I polish off the arm ends and put a spot of solder on the head to hold them.  I also simply crush the other end of the rivet with a pair of pliers, I don't try to do a "proper" rivet crimp, not needed.  One thing to note, put the rivet heads toward each other and the longer ends facing out or you'll have them clashing when you move the wipers.

Hi

May I suggest the SOLID STATE  1N3311B  ZENER DIODE, 50W, 12V, DO-5 from Newark. Yes it cost more but you will never have to replace it.

Kris

Question: When the whistle rectifier is replaced with a Zener diode, is the resistor that is wired in parallel with the diode disconnected?

Hi C.W.

This is a Don Johnson special.

"Hi, I somehow got left behind on the posts & someone started a new zener thread. I'm the one that installed the zeners in the original thread. OGR member pa told me about them. I got mine from him. He was 100% correct about how good they work.
If you have a speed change you have the wrong zeners or did something wrong.
What is your zener #?
Now... if.. you have a ZW-R the resistor is the resistor coil looking deal on the side of the whistle control bracket. The R model does not have the long wire. Only the earlier ZW has the white fuzzy resistor wire. There is also resistor wire on the early ones for the bulbs. Don't mix them up!
I have an earlier non R ZW. The resistor wire has a brass terminal spot welded (so to speak) to the bottom corner of the metal recitifer bracket. I grabbed the brass part & wiggled back/forth to crack off the terminal. Taped the end & tucked it out of the way. Tape it good."

The rest of tread can be found here.

https://ogrforum.com/t...t-it-still-speeds-up

I have used non Zender Diodes and had nothing but problems. I have replaced them all with Zender diodes using Don Johnson method and not one problem. This also includes KW transformers. Yes, they are expensive at $13.00 a pop but do it once and forget about and move on to the next project.

Kris

Yes, you remove the resistance wire.

Ive replaced several of these rollers.

I grind one end of the pin off with a

hand held metel file.

put new roller and pin in place.

crimp the end of the new pin by squeezing it

between the jaws of needle nose pliers.

I like to solder the head of the rivet as well, that removes one potentially high resistance joint.  I've seen these where there was a .5-.6 volt drop across the roller, soldering it drops that to less than half of that.  At 6 amps, typical load, that's about 3 watts dissipated right at the roller, get's kinda' hot.

I replace the rollers the same way as Gunrunnerjohn does.

Also a tip learned many years ago and use it to clean post and prewar commutators along with the windings on the ZW is a pen eraser .

Some people frown on using erasers for cleaning contacts and commutators. I have read this in multiple places. Here is one:

From Just Trains in depth article on maintenance:

that's why I carry canned air with me, blow everything clean after "erasing".

GRJ, your comment about rivets makes me think of the other use of rivets & rollers, the center rail pickups on locos.  Would make sense there also??????

It probably would make sense to solder them, though I confess I never have.  I know that I specifically had the roller in a KW smoking and when I checked the voltage drop, I realized why.  So now, when I replace rollers, the solder is another step that gets added.

As far as the pencil eraser, I don't see any reason not to use it on the indicated places.  Where you should NOT use a pencil eraser is on the gold contacts of a PCB, the very thin gold layer can be worn off by the abrasive eraser very quickly, then the contacts will be a much bigger issue!