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G6Tanuki · 23rd Apr 2021, 7:47 pm

Agreed: don't power a switched-mode-PSU monitor with a variac.

Even if it doesn't 'latch' into "I'm-being-fed-fron-120V-so-need-to-arrange-my-input-to-voltage-doubling-mode" which results in a horrorshow when you turn the supply up to 240V, if the supply has any sort of peak-current-draw constraint the poor SMPS will strive to achieve its designed output-voltages by demanding more and more current from the supply (to compensate for the low supply-voltage) - and the poor switcher's power-transistors can go into meltdown.

"Lamp Limiters" and variacs can easily kill an otherwise-entirely-healthy 1970s/80s/90s/2000s power-supply.

23rd Apr 2021, 7:47 pm	#12
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Waking up and testing Trinitron monitors Agreed: don't power a switched-mode-PSU monitor with a variac. Even if it doesn't 'latch' into "I'm-being-fed-fron-120V-so-need-to-arrange-my-input-to-voltage-doubling-mode" which results in a horrorshow when you turn the supply up to 240V, if the supply has any sort of peak-current-draw constraint the poor SMPS will strive to achieve its designed output-voltages by demanding more and more current from the supply (to compensate for the low supply-voltage) - and the poor switcher's power-transistors can go into meltdown. "Lamp Limiters" and variacs can easily kill an otherwise-entirely-healthy 1970s/80s/90s/2000s power-supply.