MX113 Power Switch

[Jacope]

Hi all. I see people often talk about the volume pot/switch on this and similar units, but usually regarding volume issues. Just got a non-working MX113. My issue is that the unit will not turn on at all when turning the knob. I briefly bypassed the switch and the unit lit up like a Christmas tree! A good sign I hope.
Is it possible to disassemble the switch to fix? Is replacement the only option? I’ve also considered installing a separate switch on the back or something. I see that people recommend using a power strip as a switch to avoid this issue, but mine came broken!

I have not tested the unit further. I’m assuming since the power section of the pot is has issues, the volume section will have issues as well - I’ll get into that later this week.

 

[AE Bob]

I have repaired some of the McIntosh ON/OFF Volume controls with a bad switch. If the switch still clicks when the knob is turned, but just doesn't make contact, you may be able to get the switch working again by cleaning the switch with contact cleaner (don't get it in the pot) or dismantling and cleaning it. If you get the switch to make contact again, you need to do a triac modification to the unit so the switch no longer carries the main AC load. The switch will only signal the triac gate, and the triac carries the load. There are several posts on the pioneer forum and others that explain the triac modification. It is not complicated.

 

[Jacope]

I have repaired some of the McIntosh ON/OFF Volume controls with a bad switch. If the switch still clicks when the knob is turned, but just doesn't make contact, you may be able to get the switch working again by cleaning the switch with contact cleaner (don't get it in the pot) or dismantling and cleaning it. If you get the switch to make contact again, you need to do a triac modification to the unit so the switch no longer carries the main AC load. The switch will only signal the triac gate, and the triac carries the load. There are several posts on the pioneer forum and others that explain the triac modification. It is not complicated.

That’s good news, mine does still click. I’ll take a look inside tonight to see what I can do. I heard of the triac mod on another post, I’ll take a closer look at that too. Thank you!

 

[ddwiggins]

Shouldn't be an issue finding a NOS or used CTS pot with switch (the manufacturer of these pots) on an auction site to rob for just the switch.

Then again that only works if the volume control resistance element wafers are still good....which they usually aren't. The carbon tracks seem to fall off the phenolic regularly, as well as imbalance issues when they don't.

Recommend you bypass the switch again and see what happens -- otherwise may be a waste of time when you need a whole volume control.

 

[Jacope]

I got a better look at the rest of the unit's functions. Somewhat surprisingly, the VC works great on both channels. A bit of static in some spots but I was able to work out 90% of it. Some humming on the tape and aux inputs I believe, I'll have to investigate further. I still have to disassemble the switch, but hopes are high!