What is it about laser printers that causes UPS manufacturers to recommend they not be powered by a "stepped approximation to sine" UPS? It's a SMSP, isn't it? What makes it special such that it needs sine-only? No such caution re. computers, etc...
Modified sine is often just full peak on, pause, full negative peak, pause, and so on. That can mess with PFC circuitry and also stresses rectifiers at the line input more than a sine. However, RVers and traveling sales folks do sometimes use modified sine inverters.
What really wreaks havoc is a printer that has a powerful fuser which draws short but huge bursts of current. That can cause the inverter inside the UPS to choke.
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They go out of their way to hide it. A friend of mine moved here with a 120 volt industrial strength HP laser printer. The specs said 325 watts, the current draw was listed as 8 amps max on the last page of the manual.
My current small Samsung printer never actually says what it draws, but the web page and manual made a big point about it drawing 6 watts in standby. Since we print around 5 times a week, the standby current matters more than the max draw, but I would not want to plug it into a UPS.
Geoff.
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Geoffrey S. Mendelson, Jerusalem, Israel gsm@mendelson.com N3OWJ/4X1GM
The main heater (the one that fuses the toner so it sticks to the paper) is usually run on a thermostat, using a big SCR (triac, to be more specific). Those SCRs can trigger on fast-rising spikes on the power line, by capacitive coupling from cathode to gate, so steps in the power-in voltage are contraindicated.
Items like a computer PS, which converts AC to DC before using the power, aren't picky.
The main heater (the one that fuses the toner so it sticks to the paper) is usually run on a thermostat, using a big SCR (triac, to be more specific). Those SCRs can trigger on fast-rising spikes on the power line, by capacitive coupling from cathode to gate, so steps in the power-in voltage are contraindicated.
So a heater of that sort takes its power directly from the line?
My point was that the 8 amps was only on the last page of the manual, not anywhere else, including the web page, sticker on the printer, specs page at the begining of the manual and so on.
Geoff.
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Geoffrey S. Mendelson, Jerusalem, Israel gsm@mendelson.com N3OWJ/4X1GM
Only 8 amps? HP is usually fairly good about supplying power consumption specs. For example, for the HP LJ 3200 all in one, see:
Inrush Current: (Duration: significantly < 1 second) Model A (120V): 23 A peak (20 deg C, from cold start) Model AB (240V): 40 A peak (20 deg C, from cold start)
With a 23A inrush current, the UPS is gonna go into shutdown, blow a fuse, or somehow complain. (I haven't tried it).
What I find amusing is that in order to get an Energy Start rating, the printer must reduce average consumption to below 50% of normal power consumption. This is usually done with a power save shut down and an "instant on" feature. However, to get reasonable startup time, the initial inrush current is really high.
My clamp-on amps guesser has a peak hold function. I'll try it out on some of my LaserJet printers in the office and see what it shows.
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Jeff Liebermann jeffl@cruzio.com
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Inkjet printers use very low power stepper motors to move the head and paper, and very tiny heaters to make the ink bubble up. They run off of low power DC. The power supply in the printer (or external on most of my inkjets) very happily converts the output of a UPS to the DC that it needs.
The difference with laser printers is that the toner only sticks to the paper as long as there is an electrical charge. To keep it falling off of the paper after a few minutes, it has to be melted onto the paper.
The technical term used is "fused" and the part of the printer is called a "fuser". They could of as easily called it "ironing" and an "iron", (as in an iron-on T shirt pattern) but that would have been too simple and not sound important enough. :-)
Geoff.
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Geoffrey S. Mendelson, Jerusalem, Israel gsm@mendelson.com N3OWJ/4X1GM
On a sunny day (Mon, 20 Jul 2009 11:14:04 +0000 (UTC)) it happened "Geoffrey S. Mendelson" wrote in :
Epson inkjets do not use heat at all, but piezo elements to push the ink out. Better, allows more more types if ink, and is faster, and allows for better control of the droplets. Yes I have couple of Epsons:-) But their service sucks as it is non-existing.
I had an Epson. Replacement ink cartridges were cheaper than other brands too, because the piezos were permanent parts of the printer and not built into the cartridges. I didn't use it often enough, and when the nozzles clogged up, the printer's life was over.
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