HP-41CX printer prints characters with white streaks. Why?



#6

I just started using my HP-41CX with external printer after being set aside for a long time. When I began printing recently, the characters were faint even though the intensity was set on normal to dark. The paper was very old, but the characters were generally well formed. As I printer the Catalog 3 a few times, the characters began to have white streaks in them. And now, the more I print, even with 3 different rolls of paper, the streaks are getting worse. While the characters are somewhat faint, because of the old paper, it is getting difficult to read them because of the increase/intensity of the streaks.

What causes the streaks, and what can be done to remove the streaks and improve the characters??

Thanks.


#7

Why? Because it probably has a twenty year old battery and paper in it for starters.

White streaks? As in not printing in those areas? Could be many things but most likely it's one of the two things already mentioned... or both.

The first thing you need is a known good battery. The printer will not work properly without one. If the battery that is currently in the unit is a 1980's original, it's very doubtful it will print properly. The normal problem is irregular width printed lines but anything is possible. The printer is a real current hog in a big way and a marginal battery will cause all manner of weirdness.

Once you know the battery is good, get some fresh paper. Any 2-1/4" wide X 85' rolls thermal paper rolls will fit.

Then see what comes out...


#8

Thanks for your comments.

The battery is old but was fully charged before installing in the printer. The voltage measured just prior to installing was 5.49 v.

I tried some old blue (82045A) and black (82175A) paper AND a new roll of OfficeMax 2.25" x 85' (OM98105) paper. If anything, the printout on the old rolls was better than the new roll -- though as noted, the streaks existed in all 3 rolls.

The streaks appear not to have anything printed in them. They are small, but often 2 streaks across the characters.

Hope this clarifies what I used in the tests.

Thanks again.


#9

Are the streaks consistent, that is, do they always appear in the same places on the characters? I've seen streaks like this caused by an old print head with "burnt out" spots on it that no longer could heat the thermal paper enough to form dots in certain positions. Since you had it put away for a long while I suppose it also could be caused by dust or other contaminants that stuck to the print head while you weren't using it. You might try blowing gently on it to see if that helps. Perhaps others here will know of a safe way to clean the delicate print head; personally, I'd be afraid of making things worse.

#10

Quote:
The battery is old but was fully charged before installing in the printer. The voltage measured just prior to installing was 5.49 v.

Unfortunately that doesn't really tell much about the state of the battery, other than that it isn't completely dead. But it can be in poor condition and still show a good voltage under no load.

I usually test the 82143A and 82162A printers by hooking up a lab power supply to the battery terminals, with the supply set to 5V. Just make sure you don't get the polarity reversed.


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