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Yamaha r-9 Replacement power supply capacitors

Winder2u said:
Well , I guess I better start reseaching which ESR meter I want. I'm sure it'll come in handy for my upcoming projects I need to work on... Yamaha M60, C80 preamp, 2 Carver m500t amps plus a few other items. Glad I'm retired.
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one of these cheap ones from eBay work great, get two so if one acts up or you drop you have a back up. Cheap enough.

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I'll be honest with ya brotha I haven't worked on this one yet. Heck, stand 10 feet away from the R-9 it's near identical to my RX-1100U, minus the class A button & Nippon Gakki logo...Mine didn't have the corrosive glue though. Does yours? Just wondered if you're familiar with the famous DSBG glue issues. The usual suspect.
 
In the pic below the one smaller black cap, the lower one closest to the wire zip strip, looks to be bulging a bit as well.
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I have an R-9 in my personal collection. I haven't restored it yet, but I can open it up and verify parts or other things if it will help you. Interested in following along with your work.
 
Winder2u said:
Main power supply caps are installed and turned it on today. Left channel weak and distorted, this is the original issue this R-9 had when I thought I would delve into fixing it. I've already replaced the supercap for the station channel memory, I'm a 71 year old amature at this stuff and I'm trying to learn and understand these smaller components. I'm sure I'll fry a few things along the way.....LOL
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Hello, my friend.


I have the same amplifier and was thinking about doing the same capacitor replacement you did. I’m also an audio enthusiast and still learning as I go.


I should mention that I also had some distortion problems. In my case, the problem was caused by the ribbon cable connecting the front panel to the vertical board mounted on the main board.


The cable connects to the vertical board through a connector, but it is soldered directly to the front-panel board. Some of the wires in the ribbon cable had developed intermittent connections, which was causing the distortion. I figured this out because the problem would temporarily disappear after giving the unit the old, reliable “smack” on the top.


I resoldered the connections and that solved the problem, although ideally I should replace the entire cable, since it was already quite deteriorated and the copper conductors would break when I tried to strip the cable.


Another thing you can do is adjust the amplifier’s bias current. The procedure is explained in detail in the service manual. In my case, the bias was considerably higher than the manufacturer’s specification, and the amplifier sounded quite harsh in the midrange and treble. Once I adjusted it to the correct value, the sound became incredibly clean and enjoyable, even for hours at high volume.


Going back to the main filter capacitors: did you notice any improvement in the punch after replacing them?


I feel that my amplifier is lacking a bit of punch, and that the bass could sound a little tighter and more controlled.


Best regards, and feel free to get in touch anytime!
 
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