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Running a Vacuum Cleaner near Tubes

I've been contemplating on asking this question, because I know what type of, highly potential, remarks this question will ensue, but here it is anyways.  Curiosity can, only, be cured by asking or doing, right??

I recall as a kid going to the local drug store, Eckerd Drugs, with my dad, so he could test the Tubes in our T.V.  A few days later, a T.V. repair man showed up at our home and he took a metal circular loop and moved the metal loop around in front of the T.V. screen.  As he did this, the picture on the screen followed the loop.  The guy said, what he was doing was realigning the picture.. AND, to never turn on or off the vacuum machine close to the T.V.

Does anyone know, not think, assume, etc., how turning on/ off a vacuum near tube gear would effect tubes?  Again, this question is, purely, out of curiosity from what I saw and hear the T.V. repair man do and say.  Thanks.

toddnlg
erik_squires
15,842 posts
 

No, it’s fine. The repairman was degaussing which is done to demagnetize equipment. Cathode ray TV’s were prone to becoming excessively magnetic which would pull the electron beam one way or another. Later generation CRT monitors had built in degaussing circuits which ran on turn on.

Mechanical watches sometimes need this too. As far as I know, signal and power tubes are not susceptible to this type of magnetic interference the same way, but I think Luxman has used a degausser for a power transformer in an amp here or there.

It’s most likely the repair person was concerned the strong magnetic motor of a vacuum could magnetize the TV screen again, especially the turn on/turn off magnetic pulses of powerful motors.

Degaussing was also done to erase magnetic tapes in bulk.

noromance's avatar
noromance
9,522 posts
 

Spot on, Erik. I did a stint on TV repair long ago and remember that well. We used to really mess up TVs in the lab by dragging strong magnets across the CRT screen to practice using the degaussing coil to fix the mess.

toddnlg OP
15 posts
 

Thanks guys!  This was extremely informative. There really is a reason and name for what the guy did. For a long time, I’ve been wanting to ask, and I’m glad I did. 

jacobsdad2000
433 posts
 

As I am very OCD I would have blown up my tube amps long ago. I vacuum every day. 

erik_squires
15,842 posts
 

I should point out, that while not likely to leave your TV magnetized anymore, motors turning on and off do cause surges in the home.  They claim most surges in a home are from this type of activity, so some amount of noise and surge protection on your delicate electronics is a good idea.  I live near lightning country so I don't run a thing without it.

 

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