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Old 5th November 2005, 01:10 AM   #1
TerryG is offline TerryG  United States
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Default I let the smoke out.

I built a stereo ZapPulse 2.3SE, and it worked fine for two months. Them one day, it stopped working and I smelled smoke. I still can't figure out what went wrong. Lars seems to be too busy for returning emails to help me figure it out, I even offered to send out the modules to him so he could see what smoked and what did not. Someone at LC audio mentioned it sounds like paracidic oscilation that smoked the amp. How and why I would like to know.

Any thoughts? The one very large resistor seemed to be what got hot, but a diode has a bubble on it as well.

I still can't figure out what is covered under warranty.

Terry
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Old 6th November 2005, 03:20 AM   #2
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Default Re: I let the smoke out.

Quote:
Originally posted by TerryG
I built a stereo ZapPulse 2.3SE, and it worked fine for two months. Them one day, it stopped working and I smelled smoke. I still can't figure out what went wrong. Lars seems to be too busy for returning emails to help me figure it out, I even offered to send out the modules to him so he could see what smoked and what did not. Someone at LC audio mentioned it sounds like paracidic oscilation that smoked the amp. How and why I would like to know.

Any thoughts? The one very large resistor seemed to be what got hot, but a diode has a bubble on it as well.

I still can't figure out what is covered under warranty.

Terry

Hi Terry,

Lars is no longer part of L.C.Audio.
Have you tried asking them to replace your modules?
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Old 6th November 2005, 09:42 AM   #3
ghemink is offline ghemink  Netherlands
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Default Re: I let the smoke out.

Quote:
Originally posted by TerryG
I built a stereo ZapPulse 2.3SE, and it worked fine for two months. Them one day, it stopped working and I smelled smoke. I still can't figure out what went wrong. Lars seems to be too busy for returning emails to help me figure it out, I even offered to send out the modules to him so he could see what smoked and what did not. Someone at LC audio mentioned it sounds like paracidic oscilation that smoked the amp. How and why I would like to know.

Any thoughts? The one very large resistor seemed to be what got hot, but a diode has a bubble on it as well.

I still can't figure out what is covered under warranty.

Terry

Is that big resistor burned out? Happens easily, happened to me once with the ZAP 2.2SE. If your amp oscilates, it may burn out.

If yo could post a picture of the affected parts, maybe someone can give a hint of what is wrong.

Best regards

Gertjan
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Old 7th November 2005, 10:07 AM   #4
TerryG is offline TerryG  United States
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I tried asking them to replace my modules, based on the warranty as it reads on their website, but no one would return my emails. I tell you what, I will try again right now and report back in a couple of days the result.

I will also see if I can post photos, I don't know if my website server will allow access from forums such as this to individual photos, I might have to creat a website just for this purpose. I have learned a lot since the amp went up in smoke, unfortunately almost every Class D amp I have made has failed at one time or another in some way.

The best sounding one I built sounded incredible, but was very noisey, because of the way we laid out the PCB, then I found others making PCB kits and modules so desided to go that route. But other designs proved to be less stable, and more tempermental. Working with class D amps is the most exciting thing I have done in electronics in years, second only to making a jacobs ladder when I was 14 years old, that was really cool, although dangerous, that was part of the excitment as well.
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Old 7th November 2005, 10:25 AM   #5
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Hi,

Yeah class d is a blast alright. So many interesting fields combined in one, highly challenging, with an end result that's astounding!

I'd like to hear more about the best one you've made someday.

Since Lars quit LC audio he has stated they'd continue their support by replacing faulty modules, this sounds like one.

I'd imagine if the level of support drops off they won't be selling too many of their new modules, do let us know how that works out. So far it isn't looking great but who knows maybe the email was lost in transmission or they're just too busy to reply? I'd still think they should have offered replacements when they decided it was parasitic oscillation that was the cause, with a newer version that's not susceptible to it.

It would be interesting to know what could cause it start oscillating for no reason, snubbing caps/resistors overtaxed and failing?

If all else fails you still have other class d alternatives.

Cheers,
Chris
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Old 7th November 2005, 10:35 AM   #6
TerryG is offline TerryG  United States
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Well I dug the amp out of a box on the top shelf of a closet in my home to take pictures of it and the PCB, and remembered some interesting things. Here is a link to a web page I created that has photos of the amp and the module.

www.geocities.com/ready4regional/index.html

The other module has not visible signs of problems but has a very loud buzz sound when powered up, in fact if blew a tweeter of a speaker of mine, even though it was only one for a few seconds.
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Old 7th November 2005, 11:34 AM   #7
ghemink is offline ghemink  Netherlands
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Quote:
Originally posted by TerryG
Well I dug the amp out of a box on the top shelf of a closet in my home to take pictures of it and the PCB, and remembered some interesting things. Here is a link to a web page I created that has photos of the amp and the module.

www.geocities.com/ready4regional/index.html

The other module has not visible signs of problems but has a very loud buzz sound when powered up, in fact if blew a tweeter of a speaker of mine, even though it was only one for a few seconds.

Wow, that looks like a big mess. I guess, as you suspect that the damaged coil maybe the reason of this. I agree, that coil, just floating in the air is not a nice thing to have. How did you kill the tweeter? Was it connected directly to the amp (so without x-over)? Or did you use a x-over?

Best regards

Gertjan
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Old 7th November 2005, 05:40 PM   #8
TerryG is offline TerryG  United States
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My tweeters have a 2 mfd capacitor in series with them, they are 16 ohms so the crossover point is around 3K Hz. The buzz is very very loud on the channel that does not have any visable damage to it, other than the big resistor looks like it got hot as well, practically all the color bars are gone.

The largest problem I have is that LC Audio was little if any help in figuring out what happened, that is more important to me than getting new modules as I really want to know how I can avoid buring up more modules. It is almost like once they decided more than likely what the problem was, with the module, I heard nothing more from them anymore. I wanted it explained to me, so I could understand. I have not heard of others having these difficulties so it must be an issolated incident, but I sure hope you folks here can give me some clue as to what happened. Can parasitic oscillations be prevented? With the one module, it is clear that the output coil got broke in shipping, but the other module perhaps can be salvaged if I knew how.

On the one definitely bad module how can I check to see if the Blackgate caps are good. I would like to save them if I can to use again, as you all know they are very pricey. I would like to use them in someway if at all possible. It is a shame what came of this project, all that money and time, I don't feel comfortable continuing with it unless I feel confident I know how to prevent more modules from burning up.
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Old 7th November 2005, 06:19 PM   #9
Nordic is offline Nordic  South Africa
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Hey don't be too hard on yourself, we al have little slips now and again, just be glad you aren't learning to become a doctor.
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Old 7th November 2005, 11:14 PM   #10
TerryG is offline TerryG  United States
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It's not that I am being hard on myself, I just don't want to buy two more modules only for them to go up in smoke as well. I mean you pay well over $300.00 on modules and you end up with junk, I have $300.00 of nothing right now. If I count how much I have in the chassis, and other projects I have a lot more invested than that, and still I don't have a working class D amplifier. No if I can learn SOMETHING, then at least that is the price of education.

I don't even want to install two new modules if they were replaced unless I can prevent them from burning out.
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