Mx113 knob stuck, pulled out pot shaft

[rollcentre]

I've never had a knob so stuck it also pulled out the pot shaft, this is the center knob on the dual concentric tone control knob for the bass on the mx113. I have the knob and shaft in the oven now trying to heat up and separate the two. Will the shaft snap back in place, or is this pot junk now?

 

[Pio1980]

Depends, you may be in over your head on this.

 

[rollcentre]

Ok thanks I guess

 

[Pio1980]

Stay in touch, help may be found here.

 

[62caddy]

I just checked A/C site. Unfortunately only the balance pot is listed. May want to email McIntosh directly. You never know...

 

[rollcentre]

Alright! I fixed it. The knob came off easily around in the oven set for 350deg. It almost looked like red locktite was holding it on.

I got the pot wipers clocked to their "max" position against the stops on the body of the pot. The pot shaft goes in with a bit of resistance, then it clicks. After the click the shaft is locked in and stays in.

It's possible to insert the shaft 180 deg out, and not all the knobs on the mx113 are indexed the same, so getting everything lined up how it's supposed to be took a minute.

 

[John James]

Did the hairs on the back of your neck finally lay down?

 

[twiiii]

I saw Davie Obrien at a clinic do the same thing one time, but with a pre-amp. You are a very lucky guy. Davie had skills. I used penetrating oil with my MR-77 one time to get a knob off. I have seen guys in the shop pull the shafts out of numerous units, but not with your success.

 

[rollcentre]

I was very lucky. The pots were oriented so I could see through the "windows" in the body of the pots. If it wasn't for that, I'd have to do it blindly.

I've had some stuck knobs before but this one had been red locktited on. There were little flakes of reddish orange bits in the knob. I had a heat gun pointing down at an angle to try and heat the knob without messing up the faceplate. I could only get it to like 150deg... Tried to wick turbine oil down into the shaft, but all that couldn't compete with it.

Thankfully after all the trauma the pot endured with the shaft being yanked out, (which looking at the design of the "step" on the end of the shaft... it's not ever supposed to do) it still works.

The other side of the "step" has a little ramp on it, so it was much easier to click back in.

But yeah, hopefully that'll the last time that happens.