Line filter\choke - gluing broken ferrite core?

[Agent24]

I've got a Dell power supply I'm recapping. Currently it's running with some substitute capacitors from another supply and I was about to do a proper replacement with good parts when I noticed that a piece of the ferrite core on the line filter has been broken off and was sitting in the bottom of the PSU case.

I'm wondering if I can just glue this back together? I know transformer cores are normally in two halves and are glued at the factory but how much difference will this make when the ferrite has broken?

Is there even any point? As far as I know the only point of the choke is to filter out the high frequency switching noise and prevent it from getting on the power line, so it shouldn't affect PSU operation - maybe just operation of anything else I have!

I was going to replace the filter with one from a dead PSU but being Dell they have used a low-profile one and the pin spacing is all wrong.

[redwire]

Re: Line filter\choke - gluing broken ferrite core?

Is the core just chipped or is it broken in two?
Gluing two halves together always results in an tiny air-gap, so the inductance ends up lower. This should not make a huge difference, just more line noise.

[Agent24]

Re: Line filter\choke - gluing broken ferrite core?

Neither, a piece has broken out of the corner. Stuffed if I know how too, it's buried in there pretty well.

[redwire]

Re: Line filter\choke - gluing broken ferrite core?

Oh it's an E-core. I would epoxy it together in two steps.
One, put in the busted piece with glue on each cracked end, snug as possible.
Two, after that dries, a big blob to keep the piece from ever falling out.
Ferrite is like glass and breaks easily. It's also conductive and shorts stuff out if it lands on the PCB.

Or just be lazy and leave it alone. The remaining two E-core legs means it will still work, although not as good.

[Trick Fix]

Re: Line filter\choke - gluing broken ferrite core?

This should not make a huge difference, just more line noise.

Good day to all,
This is my first answer.
I think the broken core can stick with and glue in a thin layer.
I believe that it will work OK,
it had already tried and works well.

It is important that the adhesive layer as thin as possible.

greeting

[Agent24]

Re: Line filter\choke - gluing broken ferrite core?

I think I will put it back together, just for 'completeness' and to hopefully further minimise noise. Easier than trying to replace the whole thing anyway.

Any particular epoxy\glue I should use?

[redwire]

Re: Line filter\choke - gluing broken ferrite core?

I use 5 minute (two-part) epoxy. Crazy glue cyanoacrylate might work, but I would put something (blob) on the core to stop the part from ever getting loose in the psu.

[Agent24]

Re: Line filter\choke - gluing broken ferrite core?

I usually use Araldite but I have run out at the moment. Thinking of getting some JB Weld for something else, would that do - or is it overkill 9000?

[Trick Fix]

Re: Line filter\choke - gluing broken ferrite core?

I know the Araldite,-good, but it's a little thick for this application,
I still think you should have to use some super glue that is very liquid,
and with it that part of the paste in which it separated.

I said earlier that it is important to glue it to the thin layer to the input Filter performance remained the same.

>I apologize if something bad interpreter<
Not in bad faith,

[diif]

Re: Line filter\choke - gluing broken ferrite core?

I'd go go for cyanoacrylate perhaps with some activator to help with the porous surface.

[momaka]

Re: Line filter\choke - gluing broken ferrite core?

Meh, all those fancy glues ... just use hot glue and be done with it.
The way I'd do it is first place the part where in needs to go, then apply a hefty amount of hot glue everywhere. Should definitely keep it from going anywhere.

Don't be like Bestec, though, and jizz glue on absolutely everything.

[Agent24]

Re: Line filter\choke - gluing broken ferrite core?

I would agree but I think Trick Fix has a valid point - the glue layer should be as thin as possible to give maximum peformance. If you look at ferrite transformers and chokes, they have very thin glue layers between the two core halves as standard from the factory.

I'll give it a try when I get around to getting some new epoxy. At the moment the thing seems to work so it's not a high priority.

[Trick Fix]

Re: Line filter\choke - gluing broken ferrite core?

http://edn.com/electronics-blogs/liv...Ferrite-Cores-

http://jimlaurwilliams.org/wordpress/?p=3337