ZW Buzzing/Humming

This is what you are looking for GEOPEG; http://www.tranz4mr.com/ZW_Type_R_Hum_Fix.html

Thanks BMORAN4, unfortunately I have an older style 275 watt ZW, not the (R). So this fix isn't applicable. That said, it IS educational - makes me wonder if I should experiment with a couple of C clamps to pinch my laminations and see if that makes a noticeable difference.

It is normal with those older transformers. The windings come loose and there isn't much you can do about it. You'll just have to replace it or put up with it.

I have had good success with using cardboard or plastic strips inserted in the coil brackets to compress the laminations to get rid of the buzzing noise.

Chuck Sartor posted:

I have had good success with using cardboard or plastic strips inserted in the coil brackets to compress the laminations to get rid of the buzzing noise.

Chuck - I would be very curious to see a photo of exactly where you placed the strips. I will be trying something similar this evening, using insulated C-clamps to determine where things need to be tightened up. It's GOT to be just a matter of loose laminations, but if they are ALL loose..... well, like BRUK said, Forgetaboutit! I'll post results later, got a VERY busy day today

Bruk posted:

It is normal with those older transformers. The windings come loose and there isn't much you can do about it. You'll just have to replace it or put up with it.

BRUK, I hope you are wrong, but the jaded side of me almoooost agrees with you   I believe that it is not the windings that are actually making the noise, but rather the laminations, and that they can somehow be trapped, compressed, bracketed or in some way jammed together to eliminate some of the noise. I will do a C-clamp test later today. I have already poked and prodded, but I'm thinking that was not the right force applied in the right place.

It's humming because it doesn't know the words!

Chief Bob (Retired)

PUFFRBELLY posted:

It's humming because it doesn't know the words!

Chief Bob (Retired)

I was going to say that. LOL

RonH posted:

PUFFRBELLY posted:

It's humming because it doesn't know the words!

Chief Bob (Retired)

I was going to say that. LOL

As they say, great minds think alike!

You could always try electrical varnish. The coils were often dipped in the stuff while being assembled. Try a electrical supply house that sells a lot of transformers.

Trainman129 is correct, each of the laminations in a transformer are insulated from each other by a thin coating of varnish to reduce eddy currents.  Technically, the cause of the noise is magnetostriction, small movement of the individual laminations due to a minute shrinking and expanding due to varying magnetic force.  As the transformers age, the varnish breaks down and the movement of the individual laminations are allowed more freely, resulting in more noise.

The solution is to dip the whole affair into a very thin varnish, probably thinned significantly and leave it for a few hours.  Let the core dry for a couple of days and it should be quieter.  You need to make the mix thin enough to get between the laminations to secure them again, kind of "factory fresh".  This will having varying degrees of effectiveness, depending on how well the varnish penetrates.  Obviously, when the cores were assembled, they didn't have the problem of getting the varnish across the whole surface.

gunrunnerjohn posted:

The solution is to dip the whole affair into a very thin varnish, probably thinned significantly and leave it for a few hours.  Let the core dry for a couple of days and it should be quieter.  You need to make the mix thin enough to get between the laminations to secure them again, kind of "factory fresh".  This will having varying degrees of effectiveness, depending on how well the varnish penetrates.  Obviously, when the cores were assembled, they didn't have the problem of getting the varnish across the whole surface.

I have heard of this being done, I've also heard of using a thin viscosity Epoxy Resin as well.

Most anything that will stick them back together would probably work.  I think the trick is getting enough of it into the core to actually do the trick.   I suspect you have to thin whatever you use to a water-like consistency to get sufficient penetration to do the job.

Aha! I opened mine up again, and despite not having the R on the bottom plate, it is indeed the "C" style core. So off I go to purchase something like a "sturdy 1" putty knife" that I can bevel the edge on and get my transformer pried apart and glued!

Any luck in just trying to compress the laminations? I haven't tried to re-glue and re-varnish the coil assembly. Do you need to unsolder all the connections from the coil?

Chuck Sartor posted:

Any luck in just trying to compress the laminations? I haven't tried to re-glue and re-varnish the coil assembly. Do you need to unsolder all the connections from the coil?

I wouldn't call it luck - I compressed the laminations from side to side (right to left sitting in front of the transformer) and found no change. I then compressed front to back, which would be pushing the end cap against the "C" portion of the lamination stack. I got noticable changes in the noise - not gone, just changed. So I'm thinking the glue trick may work for me. I'll let you know!

Too bad the 60~ hum isn't more pleasant....

Vibrations Link

Since I have several projects started and all of them currently on hold waiting on my arbor press to get modified, I thought this would be a good time to work on my buzzing ZW.

I'm very happy to say the epoxy worked like a charm! Couldn't be happier! I used ordinary epoxy purchased from Home Depot, and not "watered down" in any way. The silence is deafening....and most pleasing. I pretty much followed this guy's directions. Three hands would have been handy... I will say I spent a lot of time cleaning the end piece and the "C" section to make sure everything seated perfectly before using the epoxy.

Then came the diodes. I must have missed the step where someone described an easy way to get that 6 fingered piece of insulating paper back under the diode/lamp bracket - dang! That gave me fits x 2. I found that the speednut that holds the copper rectifier in place just popped right off both of the old discs with little to no effort - surprised they hadn't popped off a long time ago! I also found a most likely source of intermittent horn operation - the white resistance wire (1.5 ohms, per Greenberg) was supposed to be soldered to the diode bracket bear the bottom, but had a cold solder joint and was still touching, but basically was loose.

Then the breaker - piece of cake, but the dang think seems to have been assembled backwards, placing the two terminals right in front of, and touching the metal bracket - judicious bending required. That also made one of the original wires really short.

During testing, the horn operates as before, only more consistent - full on with certain engines still gives one little beep, then nothing (as before) - half way on gives a horn always, then full on may or may not keep the horn running. Need more testing with a steamy to say if there's really any improvement.

The breaker pops off MUCH quicker (2 secs or less), but I'm still not satisfied. I have ordered some Resettable Fuses from Mouser to use in some destructive testing to see if they will be quicker/better than the breaker - RXEF375, PPTC Radial Lead 3.75A 72V 40A Imax

More later

As for the whistle/horn button....did you have the top cover on while you were testing? The top cover acts like a stop and limits the travel of the button when moved. If the cover is not on, the button travels a little to far and the contacts will go past each other causing momentary contact.

Yardmaster posted:

As for the whistle/horn button....did you have the top cover on while you were testing? The top cover acts like a stop and limits the travel of the button when moved. If the cover is not on, the button travels a little to far and the contacts will go past each other causing momentary contact.

 

Yep, cover was on. I suspect it's just that engine needing a bigger DC offset. No time this morning to do more testing - family stuff. But I'll be back at it this evening...

I turn my hearing aides down when I operate my ZW.....LOL   It's not as loud as some others have posted here.  Then again, I wouldn't know for sure.  

On KW's and ZW's, the horn/whistle will drop out when the you test a tender or horn by it's self. This is normal for these transformers. Put the engine on the track and add a couple of accessory lights to the ZW and that should cure the relay dropout problem.

GeoPeg posted:

Since I have several projects started and all of them currently on hold waiting on my arbor press to get modified, I thought this would be a good time to work on my buzzing ZW.

I'm very happy to say the epoxy worked like a charm! Couldn't be happier! I used ordinary epoxy purchased from Home Depot, and not "watered down" in any way. The silence is deafening....and most pleasing. I pretty much followed this guy's directions. Three hands would have been handy... I will say I spent a lot of time cleaning the end piece and the "C" section to make sure everything seated perfectly before using the epoxy.

Then came the diodes. I must have missed the step where someone described an easy way to get that 6 fingered piece of insulating paper back under the diode/lamp bracket - dang! That gave me fits x 2. I found that the speednut that holds the copper rectifier in place just popped right off both of the old discs with little to no effort - surprised they hadn't popped off a long time ago! I also found a most likely source of intermittent horn operation - the white resistance wire (1.5 ohms, per Greenberg) was supposed to be soldered to the diode bracket bear the bottom, but had a cold solder joint and was still touching, but basically was loose.

Then the breaker - piece of cake, but the dang think seems to have been assembled backwards, placing the two terminals right in front of, and touching the metal bracket - judicious bending required. That also made one of the original wires really short.

During testing, the horn operates as before, only more consistent - full on with certain engines still gives one little beep, then nothing (as before) - half way on gives a horn always, then full on may or may not keep the horn running. Need more testing with a steamy to say if there's really any improvement.

The breaker pops off MUCH quicker (2 secs or less), but I'm still not satisfied. I have ordered some Resettable Fuses from Mouser to use in some destructive testing to see if they will be quicker/better than the breaker - RXEF375, PPTC Radial Lead 3.75A 72V 40A Imax

More later

 

 

 

Geo

glad the epoxy method worked for you. 

On the older layered cores I tried several ways of quieting the hum but never came up with an acceptable method. Generally the hum on these older transformers usually isn't bad enough to spend too much time fixing it. I have restored many American Flyer 18 and 30b transformers and found that the factory used small wood wedges to tighten the core layers to reduce hum. I haven't tried it on a Lionel yet. 

I tried the wood wedges with mixed results.  On a couple of ZW's and a KW, it really did wonders!  On several others, it didn't seem to have any effect.  It can't hurt to try I guess, but no certainty that it'll help.

Well let me just thank you again Kent S, because my wife was complaining about the buzzing, and she was up a flight of 6 steps in another room! Sitting right next to it now, it is completely silent. I never would have dreamed that it would work that well!

I have fixed many noisy ZWs with riveted cores this way. The result is always a totally quiet transformer. Unfortunately I still have not found a simple way to fix the older style cores. I wish you guys luck. 

Now if there were directions to fix the MPC era transformers that came with sets when they start doing that...