HP LaserJet 4M -- Yipes! Black stripes!

First thing is to replace the cartridge. Saying "Doesn't appear to be" won't hold much water in the real world... Sadly if you don't have a spare cardridge you are going to have to gamble that it is bad, or that you can fix the printer. Not (IMHO) a good gamble however.

Were this mine, I'd consider just replacing it, then find a used cartridge to test with (see if someone can give you one that is on its last legs...) to see if that is the problem.

Also, just for grins, clean carefully all the electircal connections to the cartdridge.

Suggest that you try the forums over on

I've a couple of 4M and 4 Plus that I've kept running with info from that site.

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Tim Phipps

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"William Sommerwerck" wrote in news:st2dnaKld-fXVR3anZ2dnUVZ snipped-for-privacy@comcast.com:

From service manual;

Table 7-17 Random Horizontal Black Lines

Possible Cause Action

Laser/Scanning Assembly Replace the Laser/Scanner Assembly. misaligned or damaged.

DC Controller PCA Replace the DC Controller PCA.

I've already looked there, posted, and been given bad advice by a resident expert. He misread my problem and assumed I was talking about vertical lines along the edge. (I have that problem, too, but it's minor.)

Unfortunately, I know no one who owns one of these printers. I'll have to call HP and some local repair shops tomorrow.

The odds are pretty good that the laser diode is failing.

This printer (made by Canon) is over 15 years old. It's a great product, and I'd rather repair it than buy a new one.

In the UK at least you can pick up these printers on ebay fairly cheap so possibly a good source of parts. As you are probably aware, the LJ 4 is the same as the 4M except for the postscript module.

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Tim Phipps

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Thanks for the confirmation of my intuitive analysis.

It's a simple fix -- but who knows what it will cost?

I found several companies selling "refurbished" 4Ms for $200 or less -- shipping included. One wonders just how "refurbished" they are, or how long they'll last.

I bought the 4M precisely because it supported PostScript, which was critical for me. I would never own a printer that didn't support PostScript. (It's nice to know that what comes out of a PostScript photosetter thousands of miles away will exactly match what you printed out in your home office.)

It's funny how the 4M was touted as a Macintosh printer, when it works perfectly well with Windows. (At the time the 4M came out, the Macintosh OS natively supported PostScript.)

You want my 2 cents worth? It's convenient how HP was able to print an exact fault that would point to a component that's not intended for the basic user to correct and local supplier to have..

This only tells me that some where along the line the flaw was found and the instruction manual updated until the end of production of that version..

Simply solution. Buy a new Laser printer of a different model.

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"I'd rather have a bottle in front of me than a frontal lobotomy"


http://webpages.charter.net/jamie_5"

We have a LJ 4M (hand me down from billing) in engineering for the occasional print job that had some paper feed problems. The repair involved replacing all the rubber feed rollers. We also have a LJ 4MV for printing 11x17 schematics and patch bay labels which was picked up on eBay 3 years back 'refurbished' for $250 and it's going strong.

If you still use parallel port for the printer, you likely won't find many (if any) of those.

GG

Well, what i would do is see if you get lucky. Take the unit apart. take the toner cart out of it. take the boards out and blow them off outside or carefully vacuum them inside. (you don't want toner dust all over).

THen carefully check connectors on the boards and check for cold solder joints. I had a LJ2 that got funky and started working when i cleaned it out and resoldered connections.

Bob

This is not a valid analysis of the situation.

Many years ago, Proctor-Silex introduced a series of "Lifetime" appliances -- toaster, iron, coffee maker. They were highly modular. If the heater base of the coffee maker failed, you simply bought a replacement. That was that. No need to schlep the item to the repair shop.

These products didn't last long, because the guarantee that replacement parts would be available indefinitely rendered it impractical for Proctor-Silex to produce "new & improved" models.

The fact is that, other than the Proctor Lifetime appliances, and the original Motorola Quasar, there have been few, if any, readily repairable consumer products. It's much cheaper to assemble everything in such a way that it becomes difficult to easily repair. * (The GE system of "value analysis", adopted by Kodak and many other companies, further complicated repairs by having one component perform multiple tasks.) As much as I would like to be able to repair a broken item simply by replacing a standard module, I realize that it isn't practical, either from an engineering or market (economic) point of view.

A printer is not a coffee maker. Photographic and electronic devices contain many components that are not, and never will be, readily user-replaceable. And once any product becomes cheap enough to be a "commodity" item, you simply toss it out rather than repairing it.

As for HP's analysis of product faults...

The description given, as was made clear, came from the service manual, not the user manual. Furthermore, this specific problem will occur in virtually _any_ laser printer where the laser or its drive circuitry deteriorates or fails. It is predictable -- and was likely predicted -- before the first _prototype_ of a laser printer was ever built! There was no "hidden flaw" for HP to find. **

As for your knowledge of laser printers...

The early HP LaserJets are classic products. The 4M, though not as fast as modern printers, is well-built and still produces beautiful output. Unless it would cost too much to repair, I have no desire to replace it with another model. That people still buy used 4 and 4M printers, and that OEM toner cartridges are still available, says a great deal about them. (The "engine" was a Canon product, by the way.)

• If circuit boards were "pluggable" and thereby "swappable", products would become larger and more expensive, and would gain new connector-derived failure modes.

** I used to own a Sony D-7S Discman. This model had a poorly designed laser diode (from Sharp) that deteriorated prematurely. I had to literally blackmail Sony to get them to fix it.

I'll bet many readers of this N.G. own one; my 4MP is the best printer on my network at the moment. It is always wise to acquire contingency spares (another LJ4) in advance; check thrift stores, back alleys in business districts, dumpsters, electronics recyclers, etc. It should be possible to maintain the machine for a long time to come.

Michael

Pull the laser mech out and clean the mirror and the laser prism. If it has a corona wire clean it. Replace the toner. Those three things usually fixes her right up. I've had to do that on so many 4m's for industrial customers back in the late 90's that i could do it in my sleep.

That's what I likely do, because I'm hoping that a bad solder joint will be the problem. I'm not sure how to disasseble it, though. But I'll probably attack it tomorrow.

Agreed. I've already found at least one seemingly trustworth eBay seller.

Your point about contingency backups is well-taken. Last year I bought a second JVC XP-A1000 hall synthesizer to cover me if my other one ever fails.

Thanks for the advice. (I've cleaned the corona wire several times.)

I know you can't "hold my hand", but I need just a bit of advice -- is it fairly easy to rip 'er apart? The cabinet "hangs" on the guts; its not easy to see where you should start dismembering.

I can buy a service manual on the Web for $7, so I won't be upset if you say "Get the manual, ya lazy bum."

The cabinet had hooks and latches. The kind where you push in on the bottom or top of the seem to pull apart. And there are some screws that although not exactly hidden, not easily spotted. My old 4m is at my office packed away so if you can't figure it out and I can locate it I may be able to walk you through the dis-assembly. If I recall correctly, one 4m that suddenly had problems got that way from a user running an envelope through it that had un-dried white-out on it. This partially blocked the opening where the laser shines through. I think another had a piece of label covering that opening. I think that opening is covered with glass. I haven't worked on a 4m in a few years but used to work on quite a few as they were pretty much the defacto business printer. They were work horses too and could be equipped with a Jet Direct card.

Ok here, just Googled this for you :)

That's one I've never run into. Do the images look perfect? What if you print out a page that is just an image, rather than something that sends truetype fonts or postscript? If bitmaps print perfectly then the problem is likely something on the main processing board.