Dan's Data letters #104

Publication date: 15 May 2004.
Last modified 03-Dec-2011.

 

The Great Toner Swindle?

I am currently looking to buy a cheap colour laser printer for family use, and Samsung's newly released CLP-500 seems like a good choice. It's cheap, has build-in duplex printing and prints decent colour images according to reviews (here and here). The only thing that troubles me is that it uses a waste toner container that fills up after several thousand prints.

Now, I have been using a monochrome laser printer from Lexmark (Optra E310) for several years, and never have to deal with waste toner. And that makes me wonder if this is Samsung's devilish little scheme to make money selling toners for a machine designed to use toner lavishly and dumping excess into the waste toner container.

Is a waste toner container a standard feature in all colour laser printers? Why is it that my Lexmark monochrome laser printer (and a couple other monochrome laser printers I have used before) doesn't need one?

Also, one of the reviews mentioned that CLP-500 is a host-based printer and hence slow compared to other printers. What makes a printer host-based and why is it slower?

Lastly, what do you think about CLP-500, is it a good buy? My family usually don't print more than 10 pages a day unless there is a report due, and even then we are talking about less than 300 pages a month. My E310 has been problem free since the beginning, but I am thinking colour and duplex capabilities will be nice. Do you think it will be a worthy investment for me?

Jeff

Answer:
Waste toner is normal; all laser printers produce it, and very few can re-use it. It's excess toner that's still stuck to the charged photoreceptor drum after it's passed the paper, to which all of the toner should have stuck, but to which it all never does.

You don't want ghosts of past drum rotations printed further down your document, so a "deflector blade" shaves off any residual toner before that portion of the drum's re-charged and re-lasered ready to have more toner applied to it. That residual, waste toner is directed to the waste receptacle, which is generally part of the cartridge in consumer printers, but may be a big separate unit, complete with agitators to shake the waste to the back of the bin, in commercial printers.

Info about waste toner is usually left out of descriptions of how laser printers work (like the otherwise excellent one here, for instance). Hunt around and you can find it, though.

A very few printers can re-use waste toner, but it's tricky to redirect it back to the main toner store, and it may have gotten dusty, and there shouldn't be much of it anyway, so it usually just gets dumped.

The only time the waste toner container's existence is likely to become apparent to users of consumer printers is if it gets filled up, which is only likely to happen if you use a cheap refill kit to avoid having to buy a new cartridge, and don't empty the waste container at the same time. The CLP-500's separate waste receptacle is unusual, but presumably forced upon it by its low-cost colour design.

Proper "remanufactured" laser cartridges shouldn't have any full-receptacle problems, by the way. The remanufacturer should clean the waste toner receptacle, as well as replace the other commonly worn out cartridge components - scratched drums, worn drum wipers, nicked deflector blades. Remanufactured cartridges may have some scratches on the outside, but they're generally as good as new, functionally.

Every consumer printer these days is host-based. All this means is that the printer relies on the computer to which it's connected to do the computational heavy lifting involved in turning the document you want to print into the actual mechanical activities the printer mechanism has to perform. This was a bit of a problem when such printers were new in the mid-90s, partly because CPUs then weren't fast enough to let you keep on computing snappily while your PC conversed (via the parallel port...) with the printer, and partly because such printers were Windows-only.

Nowadays the cheapest entry-level CPUs are quite fast enough to handle the task, and even Linux users can get decent drivers for many host-based printers.

Non-host-based printers have internal intelligence that lets them accept, say, a PostScript file as input, and spit out a document as a result (well, provided they know all the fonts you've used, so you don't get the Stuff Printing In Courier problem...). The PostScript file could have come from a PC, a Mac, a 1992 Amstrad portable that runs from AA batteries; anything. No driver required. Just copy the file to the parallel or serial port that's connected to the printer and it'll interpret it and print it.

Serious Printers can still interpret the two standard page description languages (PostScript and HP's PCL) natively, but consumer printers work just as well, for domestic purposes, by doing all of this on the host PC through the driver software.

I have no personal opinion about the CLP-500, never having played with one - but as you say, it doesn't look like a bad deal at all for the money.

 

Power pack

I've been planning an overseas trip for a while, and I want to be able to power my laptop (IBM R50) from some sort of outboard battery I can recharge with the laptop battery when I have mains power. The factory outboard battery slabs are quite amusingly expensive, running from $300USD for one that claims to be 6400mAh/95Wh, to a 9500mAh/140Wh item for another Benjamin. So a slick $AU600 for the higher capacity one.

After reading your camera battery article, I hoped perhaps a big wad of NiMH D-cells in some of these would fulfill my dreams.

This is about where it gets mighty confusing, at least for me.

On the bottom of my machine a little sticker helpfully informs me that it wants 16V, 4.5A.

However, on my battery is scribed in 0.2 point sans serif "NOM 10.8V, 6.6Ah".

Using my admittedly dodgy math skills, 1.2v*14=16.8v.

I was hoping to slap some NiMH cells into a few battery packs, wire them up, add a barrel plug, and be in business.

Question the first: Will 16.8V make my laptop explode and render me unable to procreate?

Second, will any reasonable amount of D-cells provide anything approaching 4.5 amps? Will my laptop care?

Third, can I make a similar rig out of, say, 20 D cells, and have the output be about 16 volts without mind-bending electrical theory?

I've asked around my (supposedly) knowledgeable electrical engineering student friends, but they know not if my laptop will accept such offerings.

(another) Daniel

Answer:
Regarding traveling with home-made battery packs - bear in mind that, particularly these days, such things can attract considerable attention from airport security goons. An X-ray of one of them looks very much like an Acme product that'd be of interest to Wile E. Coyote. My own old F-cell pack remains in excellent electrical condition, but sadly deprived of much of its covering tape by suspicious uniformed personnel.

Another problem: Don't assume that the laptop charger will be able to deal with a home-made pack. A pack with the same number of cells that uses the same chemistry and is connected to the same terminals inside the laptop as the original battery ought to charge OK even if its capacity is quite different from the stock one. But just hanging a barrel socket off a string of NiMH cells and connecting them to a laptop adapter that's expecting to feed the laptop's own PSU and charger circuit, which is probably feeding a lithium ion battery these days, is not a good idea. Assume that you'll need another charger to insert juice into the new pack.

A pack for a laptop may have enough cells in series that many cheap hobby chargers won't want to know about it. Really cheap hobby chargers top out at six or seven 1.2V cells; few can do more than ten. If you build the pack so that you can split it in half and connect the two halves in parallel for charging (half voltage, double amp-hours), though, a hobby charger should be fine. Many such chargers run happily from approximately 12 volts and can thus be used anywhere in the world where you can find a cigarette lighter socket, car battery charger, et cetera.

If you use a collection of NiMH D cells in regular spring-terminal holders, you can of course flick the lot of them out and charge them in a conventional cabinet charger. Not elegant, but doable.

Regarding the mismatch between the specs of your laptop's battery and its mains adapter input - it's common for devices that can run from batteries and from a mains adapter to have a lower voltage battery than plugpack. There are a few possible reasons for this; the device may just have reverse polarity protection diodes on its plugpack input that eat a few volts, for instance, and it can probably run from a range of input voltages, anyway. If it's got a vaguely sophisticated power supply inside then it's likely to draw less current when running from a higher voltage (which means the mains adapter can be smaller), yet still work OK from a battery with a couple fewer cells than would equal the mains adapter voltage (which means the battery pack can be smaller). There may be compromises, though; see, for instance, the many laptops whose screen backlight can only run at full brightness when they're plugged into the wall.

Another reason for the mismatch is that it's not possible to properly charge a battery from an AC adapter with a similar or lower nominal voltage than the battery, unless there's a step-up converter in there somewhere. Batteries have to be "peaked" at rather more than their nominal voltage to finish the charge.

If you intend to plug your home made battery into the laptop's mains adapter socket, you should try to get its nominal output close to the mains adapter voltage. 12 or 13 1.2 volt cells would probably be fine. Nine or 10 cells might cut it, but I wouldn't bet on it.

16.8 volts would probably be OK. It's only slightly more than the rated input.

The 4.5 amp current spec isn't a problem; NiMH D cells are more than happy to deliver 4.5A. Even if you buy pretty recent 9Ah D cells, though, you're obviously only going to get two hours of run time from a string of them that's being asked to deliver 4.5A.

4.5 amps is the peak demand of the laptop, though. It won't draw that much all the time. You should be able to get a decent idea of the actual run time you'll get by taking the energy content of the standard pack - 10.8V times 6.6Ah equals 71.28 watt-hours - seeing how long it lasts, then figuring out the energy content of your proposed new pack - let's say 12 9Ah D cells; that's 14.4 times 9Ah, 129.6 watt-hours - and doing the arithmetic. Assuming no losses for an external pack plugged in through the AC adapter connector, and reduced current consumption from the laptop when it gets more volts, the 12-D-cell pack will give you about 1.8 times the run time as the standard one. Allow for everything taking longer and costing more, and you still ought to get something like 1.5 times the run time, assuming the external pack's been recently charged (NiMH cells self-discharge more rapidly than lithium ion).

Once you figure out the string of cells needed for the voltage you want, you can just add more identical strings in parallel to add more capacity. If a 12-cell string ends up being a good idea, then you could rig two 12-cell strings in parallel to double your run time.

 

CE Mark pain, continued

After I ran the "Certified silence" CE-mark letter in the last column, both my original correspondent Luke and... another person... responded. Here's Luke's first comment:

Just to round off the silly CE Mark saga - I had an entertaining conversation with our supplier in which it became apparent that *none* of the 40 odd computers they'd supplied us over the last few weeks were legal and that they weren't keen on doing anything about it because their margins were so low. So I had to call in the big guns - one of our Quality Guys (yes, they're good for something!) went over to see them and read them the riot act... Trading standards etc, and offered to help.

As a result of this they're certifying all the ones they sent us, including the one built in the Antec Sonata case. Fingers crossed this means we can get more built in it, solving our noise problem. I've spoken to Antec, and they explained that they no longer CE mark their case as they have no idea what people are going to put in them and don't want to misrepresent them in any way. Final responsibility for the CE marking lies with the system integrator, as said before.

As an aside.. seeing my letter in 'print' is a fine reminder of how hard it is to actually write decent copy - keep up the good work - and if you get the opportunity to review the Antec Sonata case, have a look at it - its pretty good.

Luke

 

And then, came this:

 

Renegade CE marker

I owned a UK based PC company, and some years ago we received a letter from God knows where stating that from the x-of-xxxx we would need to ensure that our PCs were CE certified.

Initially we found that to properly certify our systems we would have to get each system type checked in an emissions chamber at an approved lab. The cost of doing this was very high. I can't remember the exact costs, but it certainly made me think that we would be unable to build custom PCs any more!

We eventually uncovered a document that basically said that we could self certify and take the risk that our equipment would not be compliant if we were ever investigated. To self certify we needed to write a document detailing why we believed our equipment would be OK. Basically the argument that all components used were CE approved and that the chassis made an effective Faraday cage would be a reasonable basis to show that we had a valid reason to "assume" that we would comply. We checked the components, checked that the cases were adequate, and carried on.

I remember that it was around this time that PCs started appearing with breakaway metal plates covering the 5.25 inch bay holes. Before this time there were just openings with plastic blanking plates on the outside. I do know that if a system has a CD0-ROM or other 5.25 inch device removed, you need to put a metal blanking plate back in so that the Faraday cage is reformed.

I also remember that there were a couple of test prosecutions in the UK at around the same time. One in Wales I believe. Again from sketchy memory, one was prosecuted for blatantly ignoring the rules, and the other was given a warning.

Sorry I can't give you chapter and verse, but this was over 5 years ago.

At the time, we built around 100 systems per month and we never had any issues. These days we are more involved with support and WANs but we still build bespoke PCs, and we still self certify.

The only test lab I knew of was run by this company. They encouraged us to get our PCs tested, but we didn't. They eventually closed the lab through lack of interest. I suspect it cost them a small fortune.

[name withheld by request]

 

I sent the above to Luke, and he said:

 

This is exactly right. Any company supplying computers made from other peoples bits is taking on the role of "Systems Integrator" and is entirely responsible for ensuring that the resultant computer is CE compliant. The usual way to do this is self certification, and hope that nobody tests it too much. Many companies work under the false assumption that if all the computer components are certified then the computer itself will be. This is not the case, because the components are certified as "components" whereas the computer is a "product". To supply a product that isn't CE certified is illegal. One wonders how many computer companies understand this - ours certainly doesn't! Hence our machine based round an Antec Sonata must be compliant, because otherwise they can't have sold it to us :-)!

Given that most companies work on the components-CE-marked-thus-system-is-too principle, the only people who can actually legally be buying these cases are the oddballs who like to build their own systems. No computer company should be supplying systems built in them. This is all rather odd. I think companies are starting to realize this - recently one computer company in the UK did indeed get badly caught out - not much fun to have all your stock seized by the Department of Trade and Industry.

The bottom line is, I think we're going to pay extra to quieten down an ENlight case that is CE marked, rather than buy systems based on the Antec one. Spend 50 extra, and make the problem go away.

Luke

If you want to ask me a question, feel free - but please read this and this first.

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