Quote:
Originally Posted by kbmuri
It's almost as loud as the Horiz Osc in my '64 Zenith console, but at a lower pitch. It's annoying enough that I wouldn't want it plugged in all the time.
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I have a digital stream converter and it is silent.
If I were you I would exchange it ASAP, while they are still available and the warranty period definitely hasn't expired... for the minimum wage clerk, don't just say it whistles, say that after 30 minutes it conks out... don't put up with defective equipment, IT will DEFINITELY die, the only question is how long it will take.
Before you accept the exchange unit, see if IT whistles....
There's probably a loose winding in the dc:dc converter's high frequency transformer, mechanically resonating at a submultiple of the switching frequency. They DON'T use 60 hz iron anymore, they rectify the line (yes, they handle 300+v just fine) , charge up a cap and drive a high frequency switching power supply.
I would expect that eventually the transformer WILL fail due to metal fatigue in the loose winding.
I have ACTUALLY seen an 8 pin DIP integrated circuit (STR_A6251), that uses a few caps, diodes and transformer and IS a complete 15 watt switching flyback power supply.