Kenwood KR-4070 stuck on headphones mode

ScienceGun

New Member
Hello again,

I decided to try my luck on Craigslist once more, and brought home a Kenwood KR-4070. Unfortunately it seems to have one major problem: the dial that is supposed to control whether it outputs to speakers A, B, or headphones does nothing. Twirl it all you like, it still only outputs to headphones. I can't even use it to turn the thing off.

I've attached a couple pictures--one of the knob in question, and one of what the knob SHOULD BE controlling on the inside.

I've never tinkered with electronics before, but in this case, I'm willing to give it the old college try. If anyone can suggest how to fix this problem--or even how to change which setting it's stuck on, so I can listen to it through my speakers, I'd greatly appreciate it.
 

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Before you dive into it, does the knob spin freely, or does it click/stop at each of the five positions; OFF, HEADPHONE, A, B, A+B?
It should stop at each position and not turn any farther counter clockwise than OFF, and no farther clockwise than A+B.
 
Before you dive into it, does the knob spin freely, or does it click/stop at each of the five positions; OFF, HEADPHONE, A, B, A+B?
It should stop at each position and not turn any farther counter clockwise than OFF, and no farther clockwise than A+B.
It clicks and stops just as you describe.
 
I thought on an outside chance that the inner part of the knob that grabs the shaft of the switch might just be loose, which would have been an easier fix. But since it's not that, I suggest you follow that link I put in my first reply. Good luck.

Oh, and one thing I learned the hard way, when you buy on craigslist, try to have the seller demonstrate that everything works. Even if you have to bring a small set of speakers with wires and one of those T antennas. I try to keep that in my car along with a small multimeter.

At a thrift store a month ago, I even left my wife at the store to hold a nice set of speakers while I went home to get some wire and a small receiver to test them with.

I've been burned before, I never trust a seller that says everything works just fine, but has no way of demonstrating that when you arrive.
 
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it might be broken then...I have worked a few and I am not aware that the metal shaft which passes thru the center for the on/off also links the sections...never tried that.

If it does, the shaft might be missing (you have to remove it to yank out the on/off portion for our patented fixes)

If the shaft does NOT link all the other sections then an additional mechanism must and thats likely not fixable.

pics?
 
I thought on an outside chance that the inner part of the knob that grabs the shaft of the switch might just be loose, which would have been an easier fix. But since it's not that, I suggest you follow that link I put in my first reply. Good luck.

Oh, and one thing I learned the hard way, when you buy on craigslist, try to have the seller demonstrate that everything works. Even if you have to bring a small set of speakers with wires and one of those T antennas. I try to keep that in my car along with a small multimeter.

At a thrift store a month ago, I even left my wife at the store to hold a nice set of speakers while I went home to get some wire and a small receiver to test them with.

I've been burned before, I never trust a seller that says everything works just fine, but has no way of demonstrating that when you arrive.
Unfortunately, I don't have a small set of speakers I could bring... And for safety reasons I prefer to meet in a public place, not a home. So it can be difficult to verify if something works ahead of time.
 
Unfortunately, I don't have a small set of speakers I could bring... And for safety reasons I prefer to meet in a public place, not a home. So it can be difficult to verify if something works ahead of time.

Yeah, I understand that. I sold a turntable to a guy that did not want to come to my home. He wanted to meet me in the parking lot of one of those Immediate Care Emergency health places. Maybe he wanted to be close to a treatment center if he got mugged. Turns out he works there.

I also have a small inverter that plugs into the cigarette lighter adapter in my car and outputs 120V AC. I used that once to test a piece of gear in a parking lot.
 
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Get the service manual http://akdatabase.com/AKview/albums/userpics/10004/Kenwood KR-4070 Service Manual.pdf

On the sixth page there is an illustration titled "replacing the rotary wafer" This is the speaker/power switch. There is a piece labeled "shaft" when people change the power wafer, they usually do it by pulling the shaft through the wafers and removing and replacing the switch. It is probably broken or missing. Usually the switch is disassembled from the front, they detents are built into the front part, and the shaft goes through the wafers and rotates them around.
 
Get the service manual http://akdatabase.com/AKview/albums/userpics/10004/Kenwood KR-4070 Service Manual.pdf

On the sixth page there is an illustration titled "replacing the rotary wafer" This is the speaker/power switch. There is a piece labeled "shaft" when people change the power wafer, they usually do it by pulling the shaft through the wafers and removing and replacing the switch. It is probably broken or missing. Usually the switch is disassembled from the front, they detents are built into the front part, and the shaft goes through the wafers and rotates them around.
All right, thanks for the manual.
 
So I have a real beginner-type question here...

A couple of the lamps are blown on this unit. I understand I can replace them with LEDs, but I've never ordered such things before, so how do I know what I'm looking for? Is there like a particular size, voltage, etc, that will "match" the ones currently installed?

And replacing them would require soldering, yes?
 
the dash lights are a 1.25" fuse light that replaces with a warm white led well, otherwise you have a lamp for the meters and stereo - all easy
 
Get the service manual http://akdatabase.com/AKview/albums/userpics/10004/Kenwood KR-4070 Service Manual.pdf

On the sixth page there is an illustration titled "replacing the rotary wafer" This is the speaker/power switch. There is a piece labeled "shaft" when people change the power wafer, they usually do it by pulling the shaft through the wafers and removing and replacing the switch. It is probably broken or missing. Usually the switch is disassembled from the front, they detents are built into the front part, and the shaft goes through the wafers and rotates them around.
So, it looks like it was the shaft after all. It wasn't connected to the knob anymore. I just wish I had realized that before I disassembled the whole dang receiver. I probably could have fixed the problem by removing the cover and using a pair of needle nose pliers to push it back in place.

As it was, I spent hours trying to restring the tuner, and it's still not quite right. The string rubs against itself at one point, creating some noise and friction. With enough use, it will probably wear thin and break, but I'm just DONE with it at this point. Maybe I'll go back and fix it later.

I also ended up with two extra screws.... That's normal, right? :dunno:

Hopefully someone down the line will find this thread and learn from my mistake. There's literally nothing holding that shaft in place, so just break out those pliers and pull it back towards the knob!

I'm frustrated, but also pretty psyched... I FINALLY have a working stereo system! Can't wait to listen to it tonight.
 
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