Spring Cleaning - power plug polarity and tube removal questions....

[Audible Nectar]

OK, I'm doing some spring cleaning and breaking down the Macs - and I have a couple of questions.


1. Is polarity of the power plugs on Macs (MC-30, MX-110, MC-250) an issue? I haven't been able to tell a difference audibly from the direction of the power plug, but if there is a right way and a wrong way that the plugs should be in the socket for polarity issues or longevity of the units, I would sure like to know.

2. I planned to remove the tubes on the MX-110 and MC-30's to clean and wax the chassis, as it seems the only way to get to all of the chassis surfaces. Other than the obvious reinstallation of those tubes in the exact same sockets, is there any reason I shouldn't attempt this?

TIA

 

[dewickt]

I wish more McIntosh owners would do spring cleaning, no issues at all. If you have some DeOxit D5, or your favorite cleaner, give the pins of the tubes a light spray when you plug them back in, just a good precaution to stop pin/socket corrosion, just like the wax on the chassis.

 

[skippy_ps]

The folks at Tuner Information Center say to orient a non-polarized plug so that you get the least "standing voltage" on the chassis. Whether they mean from the hot or neutral side to the chassis, I don't know.

Just a quickie test on a Sansui TU-517 with my analog vom shows that there is a difference - about .5 volts/0 volts one way and about .2 volts/.2 volts the other way.

Whether it makes any difference, dunno. BTW I've vaporized the ends of more than one set of probes and toasted a meter having forgoten to switch the meter to volts before sticking them on 120 vac. Wasn't very funny at the time, tho.

Murray

 

[ninohernes]

You also want to measure the voltage difference from one chassis to another. Place one probe on the amplifier, and the other probe on another piece of equipment. Read the voltage, it should be little to none. If there is any voltage present, reverse the orientation of the plug. This will also decreace the chance of hum entering your system.