Yamaha cr 2040 Phono stage static/hum

Gets

New Member
Hi everyone.

I have a cr 2040 that’s recently developed an odd static/hum on the phono input. When I first got the unit many months ago. It had a more audible, clear hum, coming from both speakers. which turned out to be a bad solder joint on the power supply board. After resoldering the bad joint. It worked perfectly.

A few days ago I was getting ready to put on a record. I go to turn it on only to hear the noise coming through my speakers. At first I thought it was the same solder joint that somehow came undone. But upon inspection, it wasn’t. So I started reading up on here and messing with the unit. Checking the offset bias and B+. All the setting were where I had set them at when I first bought the unit. But upon checking the other inputs I realized it was only coming through the phono input.
The static can be heard out of both speakers. But the hum is only coming from the left channel.
I know this isn’t very safe even with a plastic screwdriver. but While I have it open and i powered it on. And started poking around. When my hand would get closer to the phono boards left channel the hum would increase in volume. It’d also go away if my hand touched the inputs on the back of the unit. Although the static still remained.

If there’s anything there in what I wrote that can help pinpoint the problem. I’d appreciate it greatly.

I guess I should mention that I had nothing plugged into the jacks while I did all of this.
 
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Both channels ?
But the hum is only coming from the left channel.
Check the phono jacks soldered ground connections. And the ground connections for the left channel phono pre-amp circuitry.
 
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Both channels ?

Check the phono jacks soldered ground connections. And the ground connections for the left channel phono pre-amp circuitry.

The ground hum is only coming out of the left channel/speaker. But the static is audible out of both.

Alright got back to the unit. Had to step away for a while to do some other stuff around the house.

But I Checked the soldering on the phono jacks. They looked to be in good shape.

And Alright here’s where my newbie terminology kicks in. I’m not sure which is the phono pre-amp. Is it the board where all the adjustments are made? Or is it the vertical standing board near the the input jacks that has a L and R on it? Either way both look like the connectors are in good shape. The vertical board on the rear right, is the board that if my hand gets close to the caps on it. The hum volume increases. Also the hum gets quieter when I place my hand anywhere on the chassis. So I’m guessing it’s definitely a ground issue somewhere in the board.

On another note. I just realized that two lamps (right half)went out in the dial indicator. Would this have anything to do with the hum? Also the lamps seem to have been soldered in by the previous owner.

I’ve thought about taking it in. But I don’t have the time and patience to go with the renowned tech that is close by. His age and his backlog of work are too much and itd be months before I see it. the only other tech I know that’s in the area around here (Seattle, king county) has no reputation for stereo work. He is mainly known for repairing TV’s, and charging an arm and a leg.

So I’m trying to do all I can to figure it out myself before I have to make a decision on taking it in.

Edit: just realized both the boards I’m talking about are vertical. So I tried going back and clearing up my explanation.
 
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