Kenwood KA-7100 Volume Knob, please help

[blbrodie]

A few days ago I bought a Kenwood KA-7100 off of craigslist. It worked great until the volume knob became loose. I can't figure out what is going on, but there is no longer any resistance and I don't think it is connected any longer to the pole that turns.

Worse, I can't figure out any way to remove the knob. If I could remove it, I could probably figure out how it dislodged from whatever connected it to the pole. It does not pull off. There also are not any screws, although there are two holes which look like were once for screws, but they were not there when I got it and it had been working fine.

I am not experienced with this sort of stuff. I don't really do repair work, so please be simple in language. I need to figure out how to remove the volume know and/or understand how it became loose.

 

[EchoWars]

Supposed to be 1.5mm Allen-type set-screws... Get the proper tool, and you may find you can loosen the screw.

 

[blbrodie]

But if there are screws, wouldn't I be able to see them? I have an allen wrench and when I stick it in the holes, there doesn't seem to be anything in there.

 

[hpsenicka]

Are you using the correct 1.5mm allen key?

If not, your results are to be expected, as a larger key will not engage the head of the screw at all, and it will seem as though there is nothing there.

 

[westend]

The allen head set screws are very small. Sometimes it's necesary to put a small diameter wire or other into the hole to clean out the socket. The allen wrench needs to be perfectly inline with the position of the allen screw. Size should be 1.5 mm.
You should be able to see the screw head if you have a small flashlight to get the light down into the cavity.

 

[blbrodie]

GOT IT! Thanks all of you. You were right... just extremely hard to find the screw.

 

[sean sweeney]

I'm a tech in ST Louis and I've worked on THREE of these... ALL with the same problem. The volume knob spins around loose and doesn't work or someone tried to remove it and couldn't get it off. I have the CORRECT alan key and I have removed TONS of knobs... but THESE all stick !! There is an extra lobe on the end of the shaft and it's a LITTLE wider than the rest... and either the knob has corroded, warped or become suicidal... I DON'T KNOW why it's there! ...and this time I loosened the screw until it FELL out and it STILL stuck on that last lobe of the shaft! I had to get it off, because I knew I could rebuild it if it was just a matter of the tabs being pulled or loosened a lot... so I got two big standard screwdrivers in there and pried it with the force necessary to nearly rip the whole thing out of the receiver... but their it was... it was out, with a generous pile of metal shavings... and then... the BALANCE control was held on by the SAME THING, but it controls a brass sleeve that actuates the OTHER two pots... so I loosen that set screw thinking this should be easy... only it's NOT... it's basically corroded on to the brass part. It starts to come off a little and sticks... again... I'm thinking I'll fix it... it'll be ok! But then the WHOLE BRASS SLEEVE comes out and essentially ruins the whole assembly.. I still haven't gotten the brass sleeve off of the balance knob and I never want to see this piece of crap again... nice receivers... but they're cursed, like most Kenwoods I've worked on... they're just CURSED...

 

[rickl]

you could also search the Kenwood manufacturer's forum for an solution. I know you are a tech and time is money but I and a few others have had similar problems with the volume pot.

You can read how I solved the problem here. posts #10 and #12 might help.

<short answer>
open up pot whilst on control board
use a adjustable wrench on the flat shaft and remove knob
grease shaft for the future tech
reassemble
</short answer>

 

[sean sweeney]

Thanks! I was ten kinds of exasperated when I wrote that... I will probably try and still rebuild it, if possible. I think I did do one thing right, and that is I didn't FORCE the pots to turn and destroy them in this manner. I pried them, to avoid that... but yea, what a DUMB thing to do to a nice receiver! And all of them seem to have that issue... it's like they put them together with some kind of PRESS, to prevent them ever being taken apart without some major production! But I believe all the parts are still there and just need to be put back together, but I guess it's whether the guy wants me to do it. I really don't want to put aftermarket pots in there, provided I can even find the right values, because I know the pigtails on those mean they have that algorithmic rolloff for the loudness function and that's the thing that makes them "special" and not replaceable. The good thing is that all the pots still stopped where they were supposed to, even though the contact was iffy at best... and I'm sure I made that worse, but here's hoping! I'm not sure greasing it would help, really... once the metal has been scored and roughed up... I would be tempted to get the dremel and grind down that little mushroom lobe that causes all of them to stick... since they have a set screw anyway, that would probably only help. some grease on the balance knob for sure, though. I think that was just a matter of two dissimilar metals reacting against each other... I probably could have solved that issue with some penetrating oil, but I was already at the point of more Hulk than tech... lol... I know...