Service/re-cap on amplifier - is it needed?

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Toxxyc

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Hi guys,

So recently, due to the (again) incredible goodness of this forum and it's people, I have become the owner of a Yamaha RX-E810 amplifier.  The amplifier is in overall good condition, and functions well, but I suspect (and this is also the thought of the previous owner, not sure if he would like me to post his nick here) that the amplifier might be in need of a service or re-cap.  It motorboats a bit when an input cable is connected and no source is given to the amplifier.  So, this is what it does:

1.  I plug in the amplifier, connect RCA cable to the Aux input and plug the other end into my phone.
2.  Switch on the amplifier.
3.  Here the noise starts.  It sounds like a cat purring being played over the speakers.
4.  Hit "play" on my phone, and about a second before the music starts, the noise stops completely, and disappears.  It doesn't continue to make a noise for as long as any audio is given to the amplifier.
5.  Hit "pause" on my phone, and about a second after the music stops, the noise starts up again.

So far I have:

1.  Ruled out interference - Moved the amplifier away from sources of interference like power cables and my ADSL Router.
2.  Ruled out if it's on only one input (it's on all of them).
3.  Rules out cables (tested with 4 different cables, happens with all of them on all inputs).

What's interesting though is that it's dead quiet when there is no cable connected, like it should be.

Does anyone have any idea of what's happening and if it sounds like motorboating to you?  I took a video of the noise, can easily post it to YT if the need is there?

Also, if it's needed, who should I ask for assistance?  I'm not useless with a soldering iron, but I'd rather start crawling before I end up ruining a perfectly nice amplifier.  I'm moving to PTA in a week, so I'll need to look for someone who can assist close to either there or my office in Fourways, otherwise perhaps a service centre (but I'm not sure how much that would end up costing)?
 

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