Marantz 2238 - Phono stage issues

[perr0]

I just bought a 2238 receiver. Didn't have a chance to test phono input before buying, only FM and Aux.

Tested phono at home and noticed that left channel volume is MUCH lower than right channel. Made a series of tests to try to pinpoint root cause. Results below:

1. Both channels have a low hiss noise even with no TT input.
2. Balance control have to move almost all the way towards L to balance volume out.
3. When there is no sound (between record tracks), there's a very noticeable cracking/popping noise coming out of L channel
4. Sound quality when moving Balance all the way L and cranking volume is on par with R channel. Cracking/popping noise above is not usually noticeable when there's sound
5. Moving volume beyond 11 o'clock creates a TERRIBLE cracking noise out R channel (L channel, which has a much lower volume level, does not have this
6. FM is perfect, both channels sound good, no cracking/popping, even at high volumes
7. There's no jumper from Pre out to Main in at the back
8. FM sound quality seem better than TT -- I'm no expert, but TT sound quality is not what I would expect
9. TT is brand new AT120USB, plays perfectly fine through my Bose Mini Soundlink

My guess is that there is a problem with some of the phono components.
Since FM is good, I don't think it should be a problem with Volume or other control's pots.

What do you guys think?

 

[slimecity]

Have you cleaned all the controls/switches? Do this first.

 

[perr0]

Have you cleaned all the controls/switches? Do this first.

Not yet. As the problem is only related to phono, I'm assuming controls and switches have no relation to this. I have zero experience though and may be completely wrong.

I opened the cover and I believe I found the problem. Phono board have clearly been repaired and track side looks like trash. Pics below. Can I still save this board or should I start looking for replacement boards?




High resolution:
http://i.imgur.com/XP6UE51.jpg
http://i.imgur.com/ziLYZo9.jpg

 

[bluemooze]

First thing to do is Deoxitize all the controls/switches.

 

[slimecity]

It cant hurt to clean the controls first - this is a usual first step with amp restores and gets that issue out of the way as a potential problem-causer.

You are right tho - a couple of spots on the reverse of that PCB are troubling. I reckon clean it with a brush and isopropyl so you can see what is going on and then take another photo - much closer - so we can have a look.

Are you OK with soldering skills? As you will need to touch up a couple of spots there.....

 

[wlhd1610]

Omg,
There is some serious rust/corrosion on the chassis in your pic.
What's the rest of the topside look like?

Bob

 

[perr0]

Omg,
There is some serious rust/corrosion on the chassis in your pic.
What's the rest of the topside look like?

Bob

Sorry I took so long to answer, wasn't notified.

Corrosion is really bad on that region, around the phono board. I'd say 1/4 of the chassis is like that. The rest looks quite good actually. Previous owner leaves close to the sea. Maybe he left the rest covered and that area exposed.

Can I remove chassis and get rid of that rust somehow?

 

[perr0]

Just an update. Tried cleaning pots and switches. No luck. Actually, it sounds worse, I think. I'm thinking about getting a new phono board and soldering everything to new board. That board just looks nasty.