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 Post subject: Marantz 4430 stuck control
PostPosted: Jun Sun 17, 2018 12:25 am 
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Location: saint clair shores, michigan
I recently picked up a Marantz 4430. Of course some of the controls were dirty, so I sprayed them. The unit sat for a day, and then when I hooked it up, the Mode control switch was stuck. It was working fine before I sprayed it. Of course it is a rats nest of wires making it hard to see anything. I wonder if the ball bearing that creates the stops came loose and is lodged inside? Obviously I am handling this problem gently, as a broken control would be a huge repair. Any ideas? It is directly to the right of the C715 label on the pcb.


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 Post subject: Re: 4430 stuck control
PostPosted: Jun Sun 17, 2018 3:40 am 
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Location: saint clair shores, michigan
I have a feeling this is bad news. I can see the ball bearing, and it is correctly seated, and free. This makes me think the problem is with the shaft, or one of the wipers.

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 Post subject: Re: Marantz 4430 stuck control
PostPosted: Jun Sun 17, 2018 2:00 pm 
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Location: Houston, TX
Exactly what did you spray it with? If you used an extender wand on your spray can and pushed it in there, you could have bent a contact finger — time to grit your teeth and open it up for servicing. You could try to bend it back with teensy jeweler's screwdrivers and/or pick/hook tools — good luck with that.

If you didn't cause damage while spraying, I suppose you could have dislodged a foreign object (e.g., solder blob) or caked up lube with the spray and that jammed it up.
You could try tapping on the control's housing with say the plastic handle of a screwdriver, or use a small vibrating tool (massager, engraver handle, hair clipper, etc.) on it, as you gently attempt to rotate it back and forth. First try this with the unit inverted, as that may jar it loose in the opposite direction that it "went in".
You could try using shop air to try to force the foreign object out as well.
Be sure it came out completely (which means finding it), or it could jam up the control again later on.

Of course, if you used much force to try to turn the control with it jammed, then you could have at that point FUBAR'd the contact finger(s).


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 Post subject: Re: Marantz 4430 stuck control
PostPosted: Jun Sun 17, 2018 8:07 pm 
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Joined: Jun Wed 08, 2011 2:33 am
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Location: Ohio 45177
As a long shot, flushing the control would probably wash any grease out of the detent and could make it harder to turn, but if it is really frozen I shudder to think what it could be. Did you use a cleaner that is safe for plastics? Some stuff will attack plastics. That is why I like to flush switches with isopropyl. I found a little plastic pump bottle that had polaraclear optical cleaner and filled that with it, after I cleaned out any residue of the old stuff. They say spraying isopropyl is a flash fire hazard, maybe so, but on de-energized eqt, I am not worried. No open flame or anything near! Get the strongest flashlight and a small probe to move wires carefully and look into it. I suppose even a moved wire might hinder movement in the right place.


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 Post subject: Re: Marantz 4430 stuck control
PostPosted: Jun Sun 17, 2018 8:09 pm 
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Location: saint clair shores, michigan
Problem solved. Cause of problem - unknown. Here is my theory. The contact cleaner reacted with some other substance, got into the area of the switch where the shaft goes through the front piece that holds the ball bearing, and acted as a glue. I disassembled the control, including a c clip that keeps the shaft from being pushed in. I then had to pound the shaft out. Normally after the removal of the c clip, the shaft should easily slide out. The area of the shaft that contacts the front piece was black. After cleaning both parts, they slid together easily, and the shaft rotated as it should. I welcome all discussions as to the validity of my theory.

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 Post subject: Re: Marantz 4430 stuck control
PostPosted: Jun Sun 17, 2018 10:26 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Fernandina Beach, FL
1968rt wrote:
Problem solved.... I welcome all discussions as to the validity of my theory.

As you have no doubt deduced, the lubricant turned to glue, especially after you cleaned the contacts. I am sure that you will be good to go...

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 Post subject: Re: Marantz 4430 stuck control
PostPosted: Jun Tue 19, 2018 1:34 am 
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Location: Vancouver Island, Canada
Note to myself - don't just spray it and leave it. :lol:

And be careful what you use, sometimes you want a lube, sometimes not.

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 Post subject: Re: Marantz 4430 stuck control
PostPosted: Jun Sat 30, 2018 12:55 am 
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Location: Thornhill, Ontario
I think that's called "dodging the bullet"!
Cheers,
Roger

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