Searching for a Cap!

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Hello 'Freaks,

 

     I am repairing an ultrasonic cleaner and I am struggling to find a capacitor (.512uF 2000v film) with the marking CBB81-512J2000V (see pic) 

 

I am trying to go back with original equipment - I found all the others on ebay (exact replacement), but I guess I will have to substitute this one...

 

Am I being ridiculous by trying to go back with the exact same part? I only found two bad ones, but while I have it open I was going to replace all of them...I have found all but these two on ebay for less that $10 US total!

 

 

 

Thanks

John 

Just some guy

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johnrk wrote:
I am struggling to find a capacitor (.512uF 2000v film) with the marking CBB81-512J2000V (see pic)

 

Where do you get 0.512uF?

 

5100pF is more likely, especially for a Film Capacitor.

 

Take a look at this one.  Notice the 562J in the part number for 5600pF = 0.0056uF.

 

Last Edited: Sun. Dec 7, 2014 - 12:38 AM
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You're right Chuck!! :-/

 

 

 

Just some guy

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2000V?

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Yes, 2000 volts is the rating 

Just some guy

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Whats the transducer in an ultrsonic cleaner? A crystal? You charge up a cap and zap the crystal and it gets bigger or smaller or something?

 

Imagecraft compiler user

Last Edited: Sun. Dec 7, 2014 - 04:46 PM
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The small ultrasonic cleaners I've seen all used piezoelectric crystals, although I'm sure other approaches exist.

 

If one physically deforms the crystal, (either with a sound wave, or a hammer), it generates a voltage.

If one applies a voltage across the crystal, it deforms the crystal, generating motion, and hence a pressure wave.

(In this case the crystal is usually connected to a diaphragm, think of an old fashioned "crystal microphone", used backwards.)

 

The two common ways to generate the ultrasonic signal are to apply a drive signal to the crystal.

The drive signal can be set to the crystal's resonant frequency, so you get a continuous and good size physical vibration in the crystal, or one just applies a big voltage pulse to the crystal, to deform it, and it will ring at its resonant frequency.

 

Perhaps a material science engineer can chime in, (any of those on Freaks?).

I think the limiting factors on the ultrasonic cleaner are both the electrode bond to the crystal, and the destruction of the crystal by its internal (shear ? ) forces with higher drives.

 

Last Fall I spent a little time trying to measure the impedance of a small ultrasonic transducer as a function of the applied frequency.

I clearly wasn't doing it like the manufacture's set up. 

My results didn't generate the nice graph in the data sheet...

I did, however, see several mini-resonant frequencies, from say a longitudinal wave vs a transverse wave in the crystal.

Very interesting, but not what I was after.

 

The real question for John, of course, is why did the caps fail?

Old age, dried out, etc?

Or under spec'ed for the application?

 

JC

 

 

 

Last Edited: Sun. Dec 7, 2014 - 06:38 PM
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JC wrote:

 

The real question for John, of course, is why did the caps fail?

Old age, dried out, etc?

Or under spec'ed for the application?

 I am unsure - the 2000 volt ones (there are 3) did not fail. I had one fail on each board - there are three transducers epoxied to the bottom of the tank and they each have their own supply.  I replaced the blown capacitor on one supply and that transducer came  back to life. 

 

This is for a friend who uses it to clean carburetors from Mercury boat engines - the passages are so tiny that he needs to use the cleaner. My hunch is that they ran the unit without fluid and caused the caps to fail, but I have no way of knowing. I simply wanted to replace all the caps as a precaution.

 

@Chuck99 - thanks for the link - I wonder why they don't offer the 512?

 

 

Thanks

John

Just some guy

Last Edited: Sun. Dec 7, 2014 - 07:55 PM
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johnrk wrote:
- I wonder why they don't offer the 512?

 

Digikey doesn't stock the 5100pF but Mouser does.

Mouser Part #:              667-ECW-H20512HV

Manufacturer Part #:    ECW-H20512HV

Manufacturer:                Panasonic

Description:                   Film Capacitors 0.0051uF 2000VDC 3%

Pricing (USD)                  1:  $1.01

 

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Thanks Chuck!!

Just some guy

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Searching for a Cap!

Can't go wrong with this one:

 

 

Lyrics

 

I Love My Green Bay Packers

(The famous Packer Polka!)

©1993 Words and Music By

Edward J Lemberger

Esayian Publishing (BMI)

 

Tell all the people across the USA

I love my Green Bay Packers

Who won the first Super Bowls ever played

I love my Green Bay Packers

Pity Chicago, Detroit and Tampa Bay

They all come up as lackers

We take our opposition

And crunch 'em like they're crackers

That's why I love my Green Bay Packers

 

Tell that Rush Limbaugh

Tell Hillary and Bill

​I love my Green Bay Packers

Tell Willard Scott. Tell Oprah and Phil

I love my Green Bay Packers

​I'll bet even Ditka's a secret Packer Fan

He knows the best shellackers

So if you're green with envy

Wear Gold they're perfect matchers

That's why I love my Green Bay Packers

 

Bup bah da bup bah da bup bah da bah

I love my Green Bay Packers

Bup bah da bah da bup bup bah da bah

I love my Green Bay Packers

 

Don't take this wrong

But compared to old Green Bay

You're just a bunch of hackers!

So if you're green with envy

Wear Gold they're perfect matchers

That's why I love my Green Bay Packers

Yes, we take our opposition

And crunch 'em like they're crackers

That's why I love my Green Bay Packers

 

We got the best team

Go Pack!

 

 

 https://www.youtube.com/watch?v=...

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

Last Edited: Tue. Dec 9, 2014 - 12:07 AM
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laugh

 

Eddy J's site: "Singer, songwriter, certified hypnotherapist" lol

 

Eddy also has a lot of <br>'s on his home page!! haha

Just some guy

Last Edited: Tue. Dec 9, 2014 - 12:28 AM