Re: Laser printer draws current in a spike, what for?
From: John G (Greentest_at_ozemail.com.au)
Date: 08/30/04
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Date: Mon, 30 Aug 2004 19:21:22 +1000
"~Dude17~" <dude17@sacbeemail.com> wrote in message
news:b959931f.0408290758.2592a92d@posting.google.com...
> X-No-Archive: Yes
>
> I've got a laser printer that draws current in spikes and it
> makes the lights flicker as well as causing a UPS on the same circuit
> to switch over to battery due to excessive dV/dT. Unfortunately, I
> don't have a way of putting the printer on its own circuit unless I
> want to use a long extension cord.
>
> When it's in sleep state, it draws about 0.22A. When I print
> something, it draws about 8A RMS to heat up. After it's done
> printing, it stays in "ready to print" state for about ten minutes
> before going to sleep and this is where problem starts.
>
> Had the printer for a while, but I finally bothered to check it out on
> scope.
>
> I captured the event on my storage oscilloscope and this is what I
> found:
>
> At the start of cycle it draws 26A RMS for about 32mS or two cycles
> and tapers down to 8.5A RMS after 550mS. Between the start and 550mS,
> there's two spikes of about 8mS where current is only drawn from half
> of the cycle. After 550mS, the current draw drops to 0.22A RMS, then
> starts this whole cycle again after 15 seconds.
>
> If you're a visual type of person, here's the actual capture:
> http://dude17site.tripod.com/printer.html
>
> Is there a reason it needs to draw current in this pattern instead of
> spreading it out over a longer period of time?
Might be interesting if you told us what Brand/model printer you are
complaining about.
Was a know fact in early laser printers.
-- John G Wot's Your Real Problem?
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