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jeffostroff

Photos of CDI Burnt up circuit boards vs good boards, and possible only 1/2 wave?

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no pictures?? ok i refreshed the page and they were there. good photography.

Edited by CARS8
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Pretty sad these lights were even sold to people dealing with a new vendor you would think these lights would have been tested!!!!!!!!!!!!!!

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I would say bad soldering job from the warehouse in China? I have an LED Par Can for professional stage lighting, that has totally knocked out the blue LED's and i think much of it is due to poor soldering.

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The soldering is fine, I just think the cap might have been underrated voltage spec for the job it's being asked to do. I have taken 2 of these apart, and I still can't manage to get a capacitor out without damaging it, or ruining the skin where it tells you what value and voltage printed on it.

Also, It's possible that the other diode is inside the other blob, don't know the equivalent circuit, but would love to see how this one is designed.

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The circuit - along with photos - is described in detail in another thread. I'll see if I can find it later if someone else doesn't beat me to it.

The soldering is fine, I just think the cap might have been underrated voltage spec for the job it's being asked to do. I have taken 2 of these apart, and I still can't manage to get a capacitor out without damaging it, or ruining the skin where it tells you what value and voltage printed on it.

Also, It's possible that the other diode is inside the other blob, don't know the equivalent circuit, but would love to see how this one is designed.

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Yeap there are a few threads on it, but no pictures. So it's cool to see some pics of the carnage...

I've got mine in boxes ready to ship back, but I don't think any of mine burnt up like that. I had several strings start going on the last 2 nights of the show, but not any physical damage.

I was just afraid it would start a large fire and catch some homes on fire. Nothing like having a light show with the fire engines in the background spraying water all over them.. LOL

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Ok, so that explains it then. The BOM that SurferSteve listed there on that thread, if he's correct, the Diode D1 being a 1n4001, is only a 50V diode. Hmmmm. not something you would want to hook up to 110 V!

But wait.... there's more.... Look at that capacitor rating. It's a 200 volt, 10uF cap. Sound slike a pretty good strong rating.....unless you're connecting it up to 350 volts!

Someone ate way too much rice the night before! IT could be that Innovalite designed it right, but the wrong part was placed on the factory floor.

Either way, this is what happens when you don't have six sigma engineering quality standards like we did at Motorola.

Also, with capacitors, and any other item with a voltage rating, that is a spec you want to run away from, not design towards. So if your limit is 200 v, try for 100 volts. Certainly if it was a tantalum capacitor, the manufacturers tell you never to apply more than 50% of the rated voltage to the capacitor.

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Looking at the pictures here is my take on this. The part that is burning is the 68 ohm resistor, that is why the board is burnt on the top side. The capacitor looks like it would be a tantalum, but not sure.

These strings are not full wave if no diodes (2 per module) are present. They are just 1/2 wave with a small bias resistor in series with the LED's. You should see the same components in the other modules.

It could be that if they used a tantalum in a AC circuit, it probably shorted out and took the 68 ohm resistor with it. It would be like placing the 68 ohm resistor across the AC line voltage.

I would have liked to see a string of these as my curiosity keeps me informed.

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You want me to send you a couple? I've got some "extra" good and bad ones. Well, by "good" I mean "didn't flame out" but that's only because they didn't light up to begin with and by "bad" I mean "the magic smoke got out."

PM me your address and I'll mail 'em to you for your amusement.

Looking at the pictures here is my take on this. The part that is burning is the 68 ohm resistor, that is why the board is burnt on the top side. The capacitor looks like it would be a tantalum, but not sure.

These strings are not full wave if no diodes (2 per module) are present. They are just 1/2 wave with a small bias resistor in series with the LED's. You should see the same components in the other modules.

It could be that if they used a tantalum in a AC circuit, it probably shorted out and took the 68 ohm resistor with it. It would be like placing the 68 ohm resistor across the AC line voltage.

I would have liked to see a string of these as my curiosity keeps me informed.

Edited by ChuckHutchings

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No. That thread is OK but that was another one with photos of the rectifiers dissected but I think it got canned.

There's another thread under LEDs with 300-some replies that has a diagram of the circuit.

Edit: http://forums.planetchristmas.com/showthread.php?t=24389

I think this is the post Sir Chuck is referring to.

http://forums.planetchristmas.com/showthread.php?t=26924

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...Either way, this is what happens when you don't have six sigma engineering quality standards like we did at Motorola...

Oh, brother!

Hold on while I go find my boots...

:P

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Dennis:

Sorry you are way off. I already mentioned earlier it is an electrolytic capacitor. It is not a tantalum capacitor. If it was a tantalum capacitor it would be in a square yellow plastic housing. The round cylindrical capacitors are electrolytic and have liquid in them. The resistor is not the part that blows and causes the damage. A small resisitor of that size won't burn up the whole board like that.

The board burnt up because the eloctrolyte burst from the capacitor and ignited all over the board, including flowing to the underside of the board. It's possible the resistor got taken out too, but mostly this is the failure of a capacitor to overvoltage. Go to radio shack and buy a 10 uf 50 v rated cap, and hook it up to 110 v so you know it will blow, and you'll see it do the exact same thing.

A tiny little resistor simply can't make shooting flames and that much of a smoke cloud like we saw. It just blows open like a fuse.

Edited by jeffostroff

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Dennis:

Sorry you are way off. I already mentioned earlier it is an electrolytic capacitor. It is not a tantalum capacitor. If it was a tantalum capacitor it would be in a square yellow plastic housing. The round cylindrical capacitors are electrolytic and have liquid in them. The resistor is not the part that blows and causes the damage. A small resisitor of that size won't burn up the whole board like that.

The board burnt up because the eloctrolyte burst from the capacitor and ignited all over the board, including flowing to the underside of the board. It's possible the resistor got taken out too, but mostly this is the failure of a capacitor to overvoltage. Go to radio shack and buy a 10 uf 50 v rated cap, and hook it up to 110 v so you know it will blow, and you'll see it do the exact same thing.

A tiny little resistor simply can't make shooting flames and that much of a smoke cloud like we saw. It just blows open like a fuse.

I agree with you on almost all points, just maybe I did not explain it correctly. From the picture of the cut capacitor the shape looks like a tantalum, some tantalum's look like tear drops in shape. it is not exactly round like a electrolytic. Not seeing the actual module and dissecting it to confirm what it it really was. I have had a offer to send me a couple of strings of lights to confirm values of components and design.

I am very familiar with electronic components, have been in that field for over 50 years. Been a Product Engineer for many years.

Edited by Dennis Cherry

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Dennis -

Look at the pic again. You're looking at a diagonal cross-section. That's why it looks oddly shaped. It's definitely an aluminum can.

And there's no way a simple resistor cooking would generate the pressure required to rupture the casing as these things did.

I saw over 10 of them go and they looked like little Estes rocket motors. (And the smell was definitely a burning cap.)

Edit: Jeff - on another thread someone suggested using acetone to dissolve the casing. You could try that. But be careful - NO SMOKING! ;)

Edited by ChuckHutchings

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Dennis:

Sorry you are way off. I already mentioned earlier it is an electrolytic capacitor. It is not a tantalum capacitor. If it was a tantalum capacitor it would be in a square yellow plastic housing. The round cylindrical capacitors are electrolytic and have liquid in them. The resistor is not the part that blows and causes the damage. A small resisitor of that size won't burn up the whole board like that.

The board burnt up because the eloctrolyte burst from the capacitor and ignited all over the board, including flowing to the underside of the board. It's possible the resistor got taken out too, but mostly this is the failure of a capacitor to overvoltage. Go to radio shack and buy a 10 uf 50 v rated cap, and hook it up to 110 v so you know it will blow, and you'll see it do the exact same thing.

A tiny little resistor simply can't make shooting flames and that much of a smoke cloud like we saw. It just blows open like a fuse.

From these photos ( thanks tony) of a "blob" where the plastics were much more carefully removed, that doens't look like a round cylindrical capacitor. Its apperance is more like a polyester metal film cap the last time I checked.

http://forums.planetchristmas.com/showpost.php?p=248144&postcount=160

and from the stamped part numbers it was identfied as a.. 250V474J which is 0.47uf, 250V, 5%

more on this cap here

http://www.elecsound.cn/picture/CL21...0Capacitor.pdf

besides... This issue has already had several resolutions, not only temp fixes, but others as well... Hopefully the "highers to be" will concider closing this thread before it follows the same direction as others on the same basic subject matter???...rehashing over and over isnt going to change anything...

William

Edited by mnkyboy

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No. That thread is OK but that was another one with photos of the rectifiers dissected but I think it got canned.

There's another thread under LEDs with 300-some replies that has a diagram of the circuit.

Edit: http://forums.planetchristmas.com/showthread.php?t=24389

Here is a post with a link to a picture of a discected 25 count C7 string.

http://forums.planetchristmas.com/showpost.php?p=248279&postcount=179

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I think I've already boxed it up for return but I had one string where the thing burned a hole out the side of the casing. (Most of the others just came out the end where the wires are as in Jeff's photo.)

The hole was almost 1/8" in diameter.

I'll go see if I can find it and post a pic...

Edit: No luck. I'm pretty sure it was a green one and those are all boxed up and sealed already,

Edited by ChuckHutchings

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Tony's board is completely different from our board. His also has surface mount parts, and possibly that big red cap might be tantalum. On my board, the electrolytic cap was crushed before it sliced, as my slicing tool puts a lot of pressure on. So it is cylindrical cap on my board, it just got flattened out of shape.

If I had to guess, I say Tony's board is a newer rev of our board.

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besides... This issue has already had several resolutions, not only temp fixes, but others as well... Hopefully the "highers to be" will concider closing this thread before it follows the same direction as otherson the same basic subject matter???...rehashing over and over isnt going to change anything...

William

well... resolutions... haven't seen the replacement product yet so I wouldn't use the word "resolution". I still feel left in the dark on the whole issue.

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This thread is heading south very quickly.

From the other thread, the circuit in the CDI M5 100-ct strings is a voltage doubler circuit, with half of the circuitry in the blob/housing at one end of the string and the other half at the other end of the string. It is not a half-wave circuit, nor even full-wave, but closer to a DC drive for the LEDs. The caps in the circuit are probably not tantalum, because normal (non-wet) tantalum caps do not come with voltage ratings of more than 50V (at least not in the mouser catalog). Each of the capacitors in a voltage doubler circuit see just the original peak voltage, not the doubled voltage, so a 200V rating is all that is needed (although higher would be better). The diodes, however, see the full doubled voltage, and so must be rated for at least 350V (but higher would be better).

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What do you mean "heading south"?!? I don't see any complaining, bad-mouthing or name calling.

I think it's quite tame. Nobody is bashing anyone and we're just discussing Jeff's photos.

This thread is heading south very quickly.

From the other thread, the circuit in the CDI M5 100-ct strings is a voltage doubler circuit, with half of the circuitry in the blob/housing at one end of the string and the other half at the other end of the string. It is not a half-wave circuit, nor even full-wave, but closer to a DC drive for the LEDs. The caps in the circuit are probably not tantalum, because normal (non-wet) tantalum caps do not come with voltage ratings of more than 50V (at least not in the mouser catalog). Each of the capacitors in a voltage doubler circuit see just the original peak voltage, not the doubled voltage, so a 200V rating is all that is needed (although higher would be better). The diodes, however, see the full doubled voltage, and so must be rated for at least 350V (but higher would be better).

Edited by ChuckHutchings

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Yeah, there's no problem with this thread, I say we keep it going. There's also confusion going on too, because of the second links to the other photos that were interjected with this so-called "past solution". That was a completely different board from the board we have in the 100 count strings, unless the company was using 2 different designs.

I agree that the stirng is not half wave or full wave, and most likely a poor man's DC circuit. Usually when we create a DC circuit from an analog 110v line, we use a diode bridage with 4 diodes, and there is usually an electrolytic capacitor from the high voltage line to the ground line, to smooth things out, and help regulate the voltage a bit. That is a classic text book AC to DC power supply. Remember, voltage cannot change instantaneously across a capacitor, that is why caps are used in situations where you have ripple voltage, in an effort to smooth it out. This is a poor man's cheap 340V DC power supply in a nutshell.

Now, maybe we have the same problem that surfersteve and those guys worked on, I suspect we do, as the culprit in the end appears to be underrated parts.

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