OT- Mystery electronic component

[Evan]

"Re 'trasformatore'...even though that obviously translates to 'transformer' in standard English, how do you know it translates to that from Italian technical terms ? It probably does, but I wouldn't make that assumption. "

It means transfomer in technical Italian, as in electrical transformer, not a convertible robot.

[Milacron of PM]

OT- Mystery electronic component

From the board of an Indramat AC spindle drive of a 1990 vintage German CNC mill...little black cube about 5/8" cube, manuf is 'VAC'. Numbers under VAC are ZKB 409/098. Below 409/098 is -54-120. In lower left corner is X8. Six leads coming out bottom.

Search at Mouser brings up nothing. Google search brings up only hints on some foreign language sites...seems to be either 'filter' 'choke' or 'transformatore' on an Italian site...but that translates as 'transformer' ...could it be a "signal" transformer ??

The reason I'm interested in this component in particular is that it is "swelled up" with sides and top bulging out (there are 4 more on the board not swelled up), and I'm hoping it's the source of the erratic RPM behavior from this spindle drive. It may of course turn out to be a symptom rather than a source but finding out what the heck it's function is would be a step in the right direction anyway.

Any ideas ?

http://www.cedelettronica.com/ita/ca...&idmaster=4794


[This message has been edited by D. Thomas (edited 03-04-2006).]

[Leigh]

Hi Don,

It's a "trasformatore", Italian.

Appears to be a transformer, based on other components listed in the same section. I wasn't able to find any specs looking around the site.

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Leigh W3NLB

[AZSORT]

Definately a little custom made transformer that you will not be able to find. Ohm it out and compare it to the other same transformers. Its no doubt potted but sometimes you can do surgery on them to repair a broken winding. If it is bulged though, more likely it has gotten too hot and the magnet wire insulation has bubbled or burned and you are SOL. Even the schematics on that board would not give you enough info to have a new on made. Only the vendor or the engineer who spec'd it know what is buried in that potting.

[Leigh]

Hi Don,

If you're unable to find a suitable replacement, Heyboer Transformers http://www.heyboertransformers.com/ in Grand Haven, Michigan, can rewind the bad one. Send it and a good one for analysis.

Are these power transformers or signal transformers? If they're power, you should be able to find a replacement, possibly from another manufacturer. If they're in the signal line, that's a different story.

------------------
Leigh W3NLB

[Milacron of PM]

Are these power transformers or signal transformers?

I can't believe you asked that question seeing as precisely the point of my post was for you to tell me what it is !

Re 'trasformatore'...even though that obviously translates to 'transformer' in standard English, how do you know it translates to that from Italian technical terms ? It probably does, but I wouldn't make that assumption.

[J Tiers]

Apparently you must register to see more on that site.

With the small size you mention, there are two main possible functions, but they are not the only ones. A picture both sides of the board would help.

1) gate drive transformer.

2) current sense transformer

If the former, it and its "friends" will be associated with the power devices.

If the second, it will have at least two leads in series with a "fat" power trace probably leading to the drive output.

Against that is the comment "alimentatione standard" on teh site, which would seem to refer to "standard mains voltage" or "standard supply" ....Possibly due to breakdown voltage requirements, possibly something completely differnt.

If it IS one of the above, it may be a standard part.

Swelling of the part in a gate drive application would be due to something bad happening that would likely cause the drive to quit and pop fuses. Unless of course, it did that a while back and it was NOT replaced because it "still worked" and they had no replacement handy.

Swelling if it is a current sense is possible also, if the high current partly cooked it, and again it "still worked" and they didn't have another....

Eitehr way it surely could be the problem, intermittent connection etc.....

The part would also need to "isolate" a higher voltage from the control circuits. Swelled up components are generally that way from heat. Partly cooked components don't tend to do that isolation well or for long, depending on how "well done" they are. Therefore it may fail utterly and possibly with quite a lot of added damage, at any time. Or not, of course.

There are other possibilities for its use, I have nearly no data to go on, and I don't know how to register to see the rest of the data at the italian site, even if I could make sense of technical Italian.... Not to mention that the part shown isn't the same as yours in any case, aren't the numbers different?


[This message has been edited by J Tiers (edited 03-04-2006).]

[Milacron of PM]

<font face="Verdana, Arial" size="2">Not to mention that the part shown isn't the same as yours in any case, aren't the numbers different?</font>

Right, but that's the closest web reference I could get. The symptom of the Indramat drive is that it works fine at some RPM's, is "rough" at some, and doesn't work at all at the higher RPMs. For instance, if you program the drive to run at 2,000 RPM, it works great...but even at 2,000 observing the actual RPM via the drives LCD window, it varies by about plus/minus 20 RPM. If you program 1250 RPM however, the spindle sounds like it's about to throw a bearing and it's interesting that the actual RPM is varying much more in that case..plus/minus 150 RPM.

Change the speed ever so slightly, say from 1250 to 1350, and it smooths out completely...goes from sounding like the machine is falling apart to sounding like new machine !! And sure enough, observing the actual RPM, it is varying much less again..plus/minus 10 RPM. Only 'rough' at specific RPM's.

When you program 3,000 or higher RPM the actual RPM doesn't catch up to programmed RPM in time and the control shuts down due to actual vs programmed error.

And for anyone wondering, this is not a signal to drive problem...I checked signal voltage at all programmed speeds and it was 'dead nuts and rock solid'

I pulled two of these 'transformatore'...the swelled one and a non swelled one. Comparing amperages between same legs I get no differences between the 'good' one and the 'bad' one....but then I don't know what I should be measuring really.

The swelled one is pretty darn swelled, but no actual leakage from the potted area underneath...so for all I know it's working fine and a Red Herring at this point...but I sure hope not because there are no other 'smoking guns' in the drive..all other components appear as new.

I would post photos of the offending cube and it's placement in the circuit, but can't yet due to PM server flux situation.









[This message has been edited by D. Thomas (edited 03-04-2006).]

[J Tiers]

Interesting...

I am not sure why there should be a difference in behavior with RPM like that in either case I suggested. Possibly it makes sense in a way I can't see.

But the horrible noise might well be symptomatic of an intermittent output on at least one of the (presumably three) motor lines.

And, either a bad current sense OR a bad gate drive could affect that. As for the RPM deal, I still don't know.

I'd be tempted to find something non-conducting, like a chunk of plastic rod, and start tapping the drive board when running at a "good" rpm to see if it might be a vibration/resonance deal masquerading as something else.

If the two transformers (at least we think they are) measure the same, then the swelled one probably is "working" and what you see may be the residue of an old repair that wasn't completed, or wasn't done well. I'd still be suspicious, but it *sounds* like it may not be the direct problem....

If you had that current sense clamp-on I mentioned, then with your oscilloscope you could "see" the phase currents and it would be quickly obvious if there was a problem with one.

Since back when I first suggested that, I have used a regular low frequency 100A clamp-on Fluke current transformer (one that actually is for use with a DMM) to diagnose an SMPS problem. It actually gave enough high frequency info to do the job, although obviously not calibrated up there.... so it might do very well for you. If you do get one, the secondary must be "loaded" with a low value resistor (like 1 ohm, or 10 ohms for a 100:1 type) when in use...

Maybe you need that and a newer Tek o'scope.... one you can download the screen display from.... and post if there are questions....! Although, if you have a somewhat stable display, you could just take a digicam pic.

<font face="Verdana, Arial" size="2">And for anyone wondering, this is not a signal to drive problem...I checked signal voltage at all programmed speeds and it was 'dead nuts and rock solid'</font>

At what point is that? I assume you mean whatever control voltage goes into the drive power section?

<font face="Verdana, Arial" size="2">The swelled one is pretty darn swelled, but no actual leakage from the potted area underneath...so for all I know it's working fine and a Red Herring at this point...but I sure hope not because there are no other 'smoking guns' in the drive..all other components appear as new.</font>

OK, if it doesn't leak, and doesn't smell bad, it may be "simply" that the "potting" compound swelled from overheating. Insulation values MAY be OK, although if I were fixing it and had another one of those it would already be in there.

It sure sounds like maybe there is another problem, that I even more suspect may be a "left-over".

There are a couple of non-fatal ways to heat up a gate drive transformer, generally from mthe driver side... the gate side usually fails in a more "interesting" way. But that could have been in teh past....

A current sense can obviously be overheated by excess current, although that's usually harder, unless its a LOT of current, and I'd expect some other evidence to remain.....

We'll probably have to wait for pics, I'm having fun guessing, but that isn't very productive of solutions without more data.

Are there any 8 pin DIP IC parts right near that "transformatore"? Those might be gate driver chips. Any capacitors right near and connected to it?

Any heavy traces going to some leads and thin ones from two others?

[This message has been edited by J Tiers (edited 03-04-2006).]

[Milacron of PM]

J, could you send me an email, so I can reply to you with photos of this little bugger and it's surroundings ? (sorry, forgot your email address)

[J Tiers]

Sent.

Might not see it until tonight unless you send it soon.

The very quick change from good to bad over a small rpm range sounds VERY much like a vibration mode, more so than a purely electronic problem.

But that isn't absolute.... there are obscure things that could do it electronically. And it is likely to be a combo problem, vibration brings out the bad connection, etc, etc....

[This message has been edited by J Tiers (edited 03-04-2006).]

[Evan]

bump back to top

[Milacron of PM]

FWIW, I fixed the Indramat drive over the weekend. The 'cube fat boy' turned out to be working fine but was a symptom of the failure of two electrolytic capacitors "in the neighborhood".

Replaced the two dead shorted 2200 and 1000uF @ 16 volt, caps with two 25 volt equivalents from a junk power supply, and now the Indramat works perfectly.