Yamaha AX-900U

[Heiney9]

I have been looking for a decent older integrated to run a computer/office system. I aquired a pair of classic Polk Monitor 5b's and I needed something to run them. A friend had an old Yamaha AX-900U integrated just stitting around (5 years in the box of no use) so I snagged it.

Upon firing it up all the controls except the volume control were very noisy and actually caused the unit to cut out in spots. So I tore it apart and used Caig products on all the controls. This gave me a chance to remove alot of dust, etc. and see the innards.

Normally I've never been a big fan of Yamaha. Typically they tend to over complicate things and have all kinds of useless (to me) bells and whistles. This seems like a very rugged well built unit. Nice and clean inside as well as a lot of space to get at things. The internal board is marked right and left and has actuall copper power rails running down the center of the board for power distribution rather than pcb traces. Huge Nichicon 22,000 uF (x2) powers supply caps as well as a huge encapsulated transformer. Completely seperate pre-out and main-in to use as a pre or power amp only. Weigh in at a heafty 39 lbs.

It seems to sound real nice and is a powerhouse at quoted 130 wpc. Kind of renews a little faith in Yamaha and since this was built in 1987 I'm guessing the very last of the beefy Yammy's. It can't really hold a candle sonically to my Nak/Adcom seperates but it does alright.

My only concern is that after about an hour of use, idiling or light use the transformer case gets extremely hot to the touch. Is this normal? The PS caps are within centimeters of the heat and I wonder if it will shorten their life span. The output tranny's are only slightly warm. Any ideas? Should I be concerned? Any other comments on this series of amps good, bad or indifferent.

Regards
H9

[XEAGLEKEEPER]

I wouldn't worry to much about the transformer heat unless its hotter than 185ºF and the caps are 85ºC temp.rated or 221ºF and the caps are 105ºC temp.rated. Just allow ample space for cooling vents to get air.
If your really concerned you can always use a small fan.

Dave