Noisy power transformer probs - anyone?

Hey guys;

I've got a Lucid 8824 8 channel convertor - love it to death but the friggin' mechanical hum from the power tranny in this thing is unbelievable. I had the transformer replaced a year ago when I had the firmware updated but the new one is exactly the same now. I've tried everything to isolate it from the chassis, from foam bits to rubber o-rings on the bolts etc etc....nothing helps really.

So my question is this: Could a new one be made that is quiet? Someone here able to do it? I have the original tranny I could give to examine, but I have no idea of the number of turns etc etc. There are a few secondaries coming off it....figured I'd get the idea out there. I could approach a manufacturer like Plitron or ??

Anyone? Recommendations? Similar problems?

is it a special trafo or is it a simple 15-0-15 or something? toroid rated for a higher VA would probably be the ticket..

Nah it's a special one -voltage for the convertors, voltage for the digital bits, etc etc....maybe 3 different ones, been a year or so since I had it open.

What kind of package?
Typical core with steel end bells? Or is it a torroid?
You might be able to have a xfmr shop vacuum impregnate the thing with air dry epoxy if this has not already been done, but just about every pwr transformer I have seen has some type of lam treatment. It could be that the lams are quiet but the coils assy./windings are slightly loose, in which case there is not much you can do.

When they undedesign these things, they can be noisy.

If you can get the specs you could buy one from a different company.

Funny story, a winder I know got a contract to build transformers for the old Lionel train pwr supply. He had a sample that he plugged in and it hummed like a banchee. He told the company that he could get rid of the hum if he used some better laminations. But they told him "Oh no, don't do that, we Want it to hum like the old ones did"

Nestalgic marketing I guess.

Hey Cj;

it's a regular tranny, not a torroid. I'll grab the old one and see if it says anything on it...maybe try and get a pic up.

Most people here are smarter than I....but in case it helps any......

Are you sure it's just the transformer buzzing, not some sympathetic loose piece as well? How bad was the hum after you replaced the transformer........did it totally disappear?

If you're gonna get it re-impregnated, see if you can remove the end covers. I'm not a pro, but I found that with EI lams, even using vacuum assist, the coils didn't seem to impregnate fully unless I did this. ( I'm sure the pros have better equipment than I did). It'll need wet reassambly for the covers unless you coat the screws with petroleum jelly. (Actually, maybe a motor rewinder can do a vacuum varnish job for you).

If you don't go this road, I suspect that once you get the voltages up, the guys/gals around here will know some decent part you can replace with.

I've used Hammond 270CAX power transformers for two projects, and both are noisy. The enclosures also hum sympathetically.

Tightening down the end bells helped a little.

Here's an explanation (DC on the power line) and a proposed solution:

http://www.psaudio.com/articles/hum.asp

informative read. Thanks - I had been thinking that it was something in the PSU making the transformer do that - now I know that its the tranny itself.

The PS A*dio blurb is a bit misleading in that it suggests that trafos wouldn't hum if it weren't for d.c. on the line. But magnetostriction is not something that happens just for a d.c. biased signal.

I suspect PS A*dio may be overstating the importance of d.c. to sell more line conditioners. But you can find out---get a good a.c.-rated capacitor, like a motor-starting one, and put it in series with your primary. Listen to the result---I doubt that it will be night and day.

Whitlock pointed out the other day that there is a pervasive myth that system noise is due (primarily) to dirty power.

I think it is true that, if you have other interface and internal problems a noisy mains supply will make things worse. And there's nothing wrong with having good mains regulation. As well, having the tops of your sinusoids clipped off by diode-cap input loads on the mains will change your own equipment's unregulated d.c. markedly, and if you have insufficient low-line tolerance can lead to big problems.

A decent power transformer shouldbn't hum like a motherf444er. Cost cutting for mass production probably is to blame. The manufacturer probably offered a decent impregnation for $x, and the customer said no.

Hey CJ

Ya mean like these old Lionel Hummin Iron??

http://home.roadrunner.com
/~gar381/train4.jpg

They HUM good too!

GARY

Man, that looks like a cool setup!

How big is that layout!

Hummmmmmmmmmm.....

Ever have a head on collision just for kicks? :razz:

I love trains. Gotta hope a freight to Bakersfield before I croak.

Ever see Emperor of the North with Ernie and A#1?

Shack! I'm gonna get you Shack!


I didn't know O'neil was into hopping freights? :razz:

There are 10 trafos powering the layout. The trafos are all 60 to 70 years old and hummmmmmmmmmmm like hell . The hum is just part of the charm of old Lionel train trafos.

CJ your Lionel story is true.. the old lams are all loose
and make lots of noise..Got one you can take your saw to if you like!!!! The layout is 450 square feet...Lots of picts on my web site.

GARY

wow that's a killer train layout!! A friend of mine's father is in deep with HO scale stuff and has a cool assortment of train's....he used to be a television technician in the 60's and has this little workshop with all tube-based test gear...it's like stepping back in time....

Ok, back to the noisy tranny I don't want to be noisy...Here's some pics, I'll take some shots of where it sits in the Lucid(right behind the #$%^&ing front panel!) later tonite...

OK, the lams have been dipped, but I think the windings may be loose. Is there any varnish on the windings? I think it's too late to impregnate the coil, as you would have to ruin the lams to get it apart.

Looks like another transformer might be in order.

Just for kicks, plug it in (be careful) with a cheater cord and see if it humms no load.
cj

Ok got some details on the transformer from Symetrix - It's a Signal Transformer, here's a link to the specs:

A41-43-515: http://www.belfuse.com/Data/DBObject/page_09.pdf

If I had a torroid made to replace it, and fab a bracket to hold it in place(I have 50VA torroids that fit vertically in 2U so it shouldn't be a prob) is there anything I am missing here? To me it looks simply like a +/-15v tranny...nothing special. What about radiated fields etc etc? From theory I know a torroid should radiate less than an EI but also in a different pattern....just want to make sure I don't %$&* the thing up!

Here's some pics to show it's location in the chassis -