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Whining and no power

PostPosted: Wed May 04, 2005 1:42 am
by dugawug
a few times lately, my E4 has scared the shit out of me by deciding to make a repetitive whining noise instead of powering up.
the lights kinda blink with this repititive noise, but it doesn't ever power up fully.

i'm 90% sure it's the power supply, but wondering if anyone else has any ideas.

after enough trials, it does eventually power up like normal. but it's got me worried... :shock:

PostPosted: Wed May 04, 2005 2:18 pm
by et
is your fan ok
i know mine sticks here and there
esecaily if it has been of a few days
i know mine makes a scary noise if its not spinning

PostPosted: Thu May 05, 2005 6:50 pm
by duncan
doug- hi again. that's definitely the power supply. find a tech & have him replace it. a new one shouldn't cost more that $75 or so.
the power units in most of this kind of gear are "switched mode" or "switching" types, which remove the need for a large transformer & the consequent wasted energy by using the mains supply (80-300V, any frequency) to directly drive a high frequency oscillator circuit.
the output from the oscillator goes through a much smaller transformer with less wasted energy, & is then rectified & regulated into the required dc power supplies. trouble is, the oscillator circuit is running at very high voltages & frequencies, & this means that the main components have a very hard life. I call them "racehorse" components. the flickering is caused by a servo loop in the power supply; when the voltage starts to come up, the output voltages are fed back to the oscillator to rein it in.... but the circuit is now unstable because of the component failure so it never quite settles down.

I've come across this a lot at work (tv station) but I've also seen it in older proteus modules.

duncan.

PostPosted: Thu May 05, 2005 7:50 pm
by dugawug
thanks Duncan,
i think i'mma wait till it finally blows out on me, but good to know it shouldn't be too difficult to handle