Yamaha MX-635 Buzzzzzzzz.......

[jbbouwkamp]

Just picked up a Yamaha MX-635 (135wpc x 2) this morning. Eager to try it out on my Paradigms I just took out my other amp and put the Yammy in its place and buzzzzzzzzzzzzz. Both channels just buzz and music is very very faint in the back ground only when you turn the preamp volume way up. When I touch the back of the amplifier case or when I plug something into the amplifier's unswitched outlet the buzz gets louder. What's going on???

 

[ryuuoh]

Can you separate the preamp from the main?

 

[jbbouwkamp]

Actually I think I just found out the problem. I was reaching behind the component when plugging the interconnects to the input so didn't realize what was going on. I just pulled the unit out of the rack and noticed the outer metal covering around the rca on both L and R channel is missing. Never seen that one. I'm going to steal the RCAs plugs from one of my "dead" components and slip it in and a solder to see if that works. Guessing it will fix the problem. Let you know!

 

[avionic]

Main power supply filter cap(s)...:scratch2:

 

[avionic]

Actually I think I just found out the problem. I was reaching behind the component when plugging the interconnects to the input so didn't realize what was going on. I just pulled the unit out of the rack and noticed the outer metal covering around the rca on both L and R channel is missing. Never seen that one. I'm going to steal the RCAs plugs from one of my "dead" components and slip it in and a solder to see if that works. Guessing it will fix the problem. Let you know!

That will do it as well....:yes:

 

[jbbouwkamp]

OK...not quite so easy. Having never replaced RCA inputs I see that these things are all different on the backside. Any suggestions on how to replace these??? Or, can I just pull the steel "ring" off the RCA of one of my other spare component's inputs and super glue it on???

 

[avionic]

They are probably soldered in place...

 

[ryuuoh]

Pics will help.

 

[jbbouwkamp]

See pics for view of inside of amp and the problem RCA inputs. Any suggestions for replacing/repairing these?

 

[ryuuoh]

What happened to the original sleeves? You could get creative and sort out how to reinstall the old ones, with some glue, or just buy some wbt replica rca jacks and wire those to the board.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=091-1120

BTW, I'll bet you were using those snazzy tight fitting interconnects. They've been known to wreck old rca jacks.

 

[jbbouwkamp]

Don't know...guessing originally owner has them wedged in some interconnects somewhere.

 

[cademan]

Frequent your local salvation army or goodwill stores. A lot of donated equipment uses that same style jack assembly.

Also, a quick fix would be to run a seperate ground wire from a ground connection PCB on the preamp, to the ground connection on that little circuit board that houses the RCA jacks for the amplifier.

 

[avionic]

A pair of these vampires would look Sweet...