matthews@TCGOULD.TN.CORNELL.EDU.UUCP (02/14/87)
Since my department got a LaserWriter, all of a sudden I'm interested in
in technology I previously just let other folks worry about. If the
photocopier was making lousy copies, it was easy to find and bitch at
whoever was in charge of the care and feeding of the monstrosity. But
it looks like I'm going to be partly responsible for keeping the LW running,
so I guess it's time to do some research.
I gather that virtuousness in print engines is measured in pages/minute,
which I can understand, and pages/month. The latter units seem to apply to
some variable related to mechanical robustness. The LaserWriter sits on the
low end of both parameters, which doesn't surprise me I guess. But what's
supposed to happen if we use it more heavily than its allotted 3000/month?
I.e., what does "duty cycle" measure?
-- Dave Matthews
There was a tide in the affairs of men...
ARPA: matthews@batcomputer.tn.cornell.edu
USENET:...{cmcl2,shasta,uw-beaver,rochester}!cornell!tcgould!matthews
PAPER: Dept. Plant Pathology, Cornell University, Ithaca NY 14853 USA
BELL: 607-533-7820 DISCL:My employer ignores my opinions altogether.phil@RICE.EDU.UUCP (02/20/87)
> But what's > supposed to happen if we use it more heavily than its allotted 3000/month? > I.e., what does "duty cycle" measure? Not bloody much. We have an Imagen 2308 (formerly 8/300) which is based on the Canon LBP-CX engine (same as, I believe, a Laserwriter). We received it in January of 1985 and have averaged between 4000 and 6000 pages per month on it ever since. That's well over 100000 pages in two years---and that's a pessimistic estimate. Have we had problems with it? Of course! But 80% of the problems were with Imagen's processor box, not with the print engine (we've replaced the power supply and just about every board in the processor). Aside from replacing the silly plastic "paper separator" every few months, only two things went wrong with the print engine. First, we had to replace the fuser roller assembly---the very last set of rollers in the paper path. This assembly is responsible for heating and "fusing" the toner to the paper. The assembly is not designed to last more than, I think, about 50000 pages. Sooner or later, you have to replace them. Second, the clutch mechanism that drives the paper pickup roller (the roller that actually picks up paper out of the paper tray) slowly gave out over the course of several months. The result was a groaning sound accompanied with a noticeable temporary decrease in the speed of the paper path. In other words: the paper would actually slow down for a few seconds while the mechanical engine would groan and moan. For some reason, the image processor software 2.2 was able to cope with this slow-down, although Imagen technical support was very surprised by that statement (and probably didn't believe it). But the new software/ hardware, 3.3, was not. The image would come out squashed at the bottom of the page. So, we finally had to say goodbye to the 2 year old print engine and replace it with a refurbished one. I think that duty cycle is an estimate of how hard you can push your print engine and still have it perform optimally. But the estimate is purposefully a pessimistic one. We pushed our engine well past that limit, and it still lasted for two years. We could have had that specific engine repaired and refurbished and returned to us, but that would have taken longer than just having it replaced with an already refurbished one. So our two year old engine is actually still in commission---it was refurbished and sold to another customer. We just don't know where it is. William LeFebvre Department of Computer Science Rice University <phil@Rice.edu>
henry@ucbvax.Berkeley.EDU@utzoo.UUCP (03/10/87)
> > I.e., what does "duty cycle" measure? > > I think that duty cycle is an estimate of how hard you can push your > print engine and still have it perform optimally. But the estimate is > purposefully a pessimistic one.... Be careful. Experience with the Canon LBP-CX engine does not generalize to larger engines. The LBP-CX is famous for tolerating gross violations of its duty-cycle rating. (There are people at LBL using it at TEN TIMES the nominal 3000/month duty cycle.) On larger print engines, the duty cycle rating apparently must be taken very seriously or your maintenance bill will skyrocket and reliability will nosedive. Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,decvax,pyramid}!utzoo!henry
phil@RICE.EDU.UUCP (03/11/87)
>Henry Spencer > Be careful. Experience with the Canon LBP-CX engine does not generalize > to larger engines. The LBP-CX is famous for tolerating gross violations > of its duty-cycle rating. (There are people at LBL using it at TEN TIMES > the nominal 3000/month duty cycle.)... Then I submit that the published duty cycle of the LBP/CX is wrong! If indeed a figure called "the duty cycle" actually has meaning for other print engines, and if in fact that figure is pretty "spot on", then someone miscalculated the duty cycle for the LBP/CX, because most everyone seems to agree that these little guys can be pushed way beyond 3000 pages/month. How do laser-printer/copier manuafacturers decide on this mysterious figure? Why was the LBP/CX given the rating it was? Why does it appear to be so wrong? William LeFebvre Department of Computer Science Rice University <phil@Rice.edu>
roy@phri.UUCP.UUCP (03/21/87)
> How do laser-printer/copier manuafacturers decide on this mysterious > figure? Why was the LBP/CX given the rating it was? Why does it appear > to be so wrong? This is mostly conjecture, but guess it's mostly a marketing decision. I've heard 2 numbers for the LBP/CX -- 3k pages per month (duty cycle) and 100k pages total expected lifetime. Assuming the latter is accurate and the former is bullshit, that's about 3 years of normal use. But we put something like 5k pages a month on the machine so I only expect it to last 2 years. If we did 10k a month, I guess it would only last 1. I suspect that many people wouldn't buy a printer they knew would only last a year so they fudge the numbers to make it look like it'll last 3 (a reasonable amount of time for a high-tech, moderate-cost item like the Apple LW/LW+). I personally think of LW's as disposable -- the BIC pens of the laser printer industry. I'd rather spend $3800 on a printer that I know I'll have to throw out in a year than spend several times that on a machine which will still be running strong long after it's obsolete. Think about it: 5 years from now won't you be wishing you had an excuse to trash that stupid 300 dpi machine even if it still works? Our current philosophy is to always have one LW in perfect condition; as it gets beat up we buy a new one and use the old ones for draft (we now have 3), putting brand new cartridges in the best printer and rotating them to the draft machines as they start to run down.