Transformer issue

But will testing catch the ones that are almost sort of not quite shorted yet, but will be after you ship them to your customer?

--
www.wescottdesign.com

You stop in every couple or few weeks, and do nothing at all except spew horseshit into the groups. That is all you do any more. Not that you ever did much else.

Solder it by hand post flow soldering

Possible that different core material is being used, which is more sensitive (read: saturates easier).

I was just gonna say that ...

Increased field returns is the worst that can happen because customer perception is involved at that point. Cost calculations can become almost meaningless then. If it was me my decision would be clear, don't risk it and solder them on by hand until the mfg has definitely and verifiably fixed the problem.

Keith: Maybe call the decision makers before leaving for the week? Seriously ...

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Not only are you always wrong, AlwaysWrong, but you're a damned liar, as well. Of course this is nothing new to anyone who has ever so much as heard of the Usenet.

Not only are you always wrong, AlwaysWrong, but you're a damned liar, as well. Of course this is nothing new to anyone who has ever so much as heard of the Usenet.

The vendor has assured us that if the reflow doesn't get them, they'll live a normal life. I've already asked, more than once.

Agreed. Already been there.

Done. I got together with the other hardware engineer and my boss today and laid out the alternatives, stressing that the owner and the "CTO" must understand all the alternatives and risks. They can make the decision.

I think we have something like 2,000 transformers in inventory, if we could get the new ones today, I'm sure they'd scrap the $2K worth of inventory without a blink. However, it's the Chinese new year, so it's taking a while to get new parts made. Manufacturing will pitch a fit over manually placing that many, though.

BTW, someone suggested another supplier. I grabbed a board we made about a year ago, with another vendor's transformers on it (we couldn't get these) and one of two (the others had already been replaced) failed the test.

He seems to have bought the truth from Andrew, as soon as the mechanism was explained.

Sylvia.

On that one I would not trust the vendor, at least not without having seen a disected transformer myself. What if the insulation softened and then solidified again? What if some of it has become really thin?

Great. That's the right thing to do, you pressed the big alert button and now everybody is in the know about the situation.

Allow them time-and-a-half OT, bring in home-made pie and they'll be happy :-)

Drat. But if they used the same sort of wire it's not really a surprise.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

"Joerg" krackpot wanker

** There is guaranteed to be damage to ALL the transformers and some with shorted adjacent turns going un-noticed at the moment.

Sounds like the Chinese vendor is WELL aware of the problem and has a nice * line of bullshit * to tell customers all worked out. Standard operating procedure for such situations.

The idea of using a higher temp grade of winding wire is probably a blatant lie too.

Firstly, why are they not using it already ???

Secondly, the wire is likely hair fine and getting high temp insulation on such fine wire is very expensive.

..... Phil

Don't bother with Phyllis, it's off it's meds, again.

I wasn't clear. The other vendor's transformers aren't nearly as good in the application but we couldn't get the one that we found were failing in reflow. It turns out that the others did too.

...and cores. The construction is the same, so it's no real surprise that both failed the same way.

You just answered your own question, stupid.

krw loves Phylis

#6

Six to go. Want more?

--
Not casting aspersions, but it sounds to me like someone needs to take a
good long look at the transformers and find out why they're failing
instead of believing vendors who're playing CYA.

JF

"John Fields"

** Acronyms are ODS ....

.... Phi

Even if we had the resources, what this going to tell us? We aren't about to make the transformers. There are only so many suppliers and none have any that work well enough in the application. They're also willing to modify them to meet our needs.

--
Of course I don't know the whole story, but the problem, in my view, is
that you're letting your vendors write the spec's when what they
_should_ be doing is building stuff that meets the spec's _you've_
written.

Kind of like the tail wagging the dog.

As for modifying them to meet your needs, it sounds to me like what's
going on is: "That didn't work?  OK we'll try something else." 

JF