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Old 09-25-2020, 11:43 AM   #4
momaka
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Default Re: Denon AVR-X2000 mainboard caps bulging

Was the bad Carli X2 cap placed across the incoming AC power lines for the 5VSB supply?

If yes, I suspect the amp might have seen a power surge on the line while it was on. Since the large Elna caps are connected to a linear (line transformer) power supply, it is possible that if there was a surge indeed, it damaged the output caps. I mean, I've seen one-offs with cheapo cap brands, where one of those large filter caps would open/bulge/go bad on a linear PSU like this. But since both of your caps have failed, I'm leaning more towards power surge. If you're in the USA or in a country that provides 2-phase residential AC with a center-tapped Neutral (most houses in the USA), then a bad Neutral connection could surely cause something like this.

Either that, or the unit was severely overheated for most of its life... thought I think this case is a lot less likely to be possible, because if the amp is to get so hot as to cook the caps, imagine how hot the transistor heatsinks would have gotten. Surely an output transistor or one of those 78xx linear regulators would have fried way before then. And you would have noticed this on the solder side in form of darkened / burned PCB, despite the PCB using a dark brown color (which IMO is the worst when it comes to troubleshooting.)

Last edited by momaka; 09-25-2020 at 11:49 AM..
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