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Amp cutting out at high volumes

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axellieb

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Looking for a leaking capacitor?

As mentioned in the OP, this amp has just come back from the Marantz service center. I specifically asked them if the capacitors don't need to be replaced and they said no.
 

sonitus mirus

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Auto-thermal reset from abrupt peaks could be attributed to older capacitors if they are not functioning properly. This is an older model with the original caps.
 
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axellieb

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Auto-thermal reset from abrupt peaks could be attributed to older capacitors if they are not functioning properly. This is an older model with the original caps.

But again, this amp was looked at by Marantz service just a week ago, and again, I specifically asked about the caps. The guy told me there's no need to exchange the caps. Though I'm not sure what he based that assessment on. Visual inspection? Testing? Experience?
 

sonitus mirus

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But again, this amp was looked at by Marantz service just a week ago, and again, I specifically asked about the caps. The guy told me there's no need to exchange the caps. Though I'm not sure what he based that assessment on. Visual inspection? Testing? Experience?
If they are not bulging and no oily residue is seen at the base, they are not obviously failing, but it is an older unit and it could be possible that they are showing some age and the amp might perform better if these were replaced. I mean, they are working fairly well it seems, so any problems would not be glaring, I would think, unless something changed recently.
 
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axellieb

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If they are not bulging and no oily residue is seen at the base, they are not obviously failing, but it is an older unit and it could be possible that they are showing some age and the amp might perform better if these were replaced. I mean, they are working fairly well it seems, so any problems would not be glaring, I would think, unless something changed recently.
OK, so would you suggest sending the amp to Marantz once more and asking them to replace the caps, whether or not they think there's anything wrong with them?
 

sonitus mirus

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I would correspond with them first, to see if they might be able to provide any useful information. I'm just guessing about possible issues with a very limited amount of data to support it. You might be able to verify if the any of the caps are in need of replacement. Maybe somebody can respond with some better ideas.
 

Cbdb2

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If you just got it back from the service center and its not working properly they should fix it for free, including shipping, there its there mistake. They might want to know your not over driving it. Do you have a volt meter? If so run a 300hz tone and measure the voltage the amp quits at. This would tell us all a lot.
 
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axellieb

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Well, just spoke with the Marantz guy again (I live in Japan, it's Monday afternoon here). He thinks what's happening here is probably normal. It's just that I didn't have this problem earlier because I lived in apartments where I couldn't crank it up like I can now. And also, my living room is now a decent size while previously it was small. So these speakers are probably just really difficult to drive.

He is quite sure that there is nothing wrong with the amp. They performed load tests on it, and it all looked normal to them. He was adamant that capacitors have nothing to do with this situation. They don't degrade materially in 25 years, according to him. And there are over 100 of them in this amp. Exchanging them all would be ridiculous and highly unlikely to produce any results. On the other hand, if the speakers are of the same age, then some degradation in those might cause premature cut-outs, especially if bass seems to be the issue. Which they are, and which it does.

I can do the measurement you, @Cbdb2 , suggested next time an electrician comes here. An air conditioner needs to be installed. That will happen in the next few weeks. I can ask the guy to help me with that measurement.

Ultimately though, this probably boils down to getting new speakers. I've been ogling the Wharfedale Diamond 12.3.... If the amp still gives me grief with those, too, I'll have a firm basis for complaint. WhatHifi even tested them with the much less powerful Marantz PM6007 and had no issues.

Thanks to everyone here for your comments!!
 
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