steve@altos86.Altos.COM (Steve Scherf) (12/13/90)
I just thought I would share a fun experience with you all. After buying
and learning how to use an infrared printer for the 48sx, I was quite impressed
by thermal printer technology. It really seems neat how you can just print
and print and never have to replace a ribbon or ink cartridge. Then one
day (when it was a mere two weeks old) I turned it on, and POOF! A little
column of smoke rose from the area of the printing head. When it attempted
to print what I had sent to it, it just made a bunch of black streaks on the
paper. The spot on the paper where the head had been at rest had a hole burned
through, and the rubber platen behind it had melted. That head must have
gotten really hot to do that. The bubbled and warped plastic on the head
itself was testimony to that.
I sent it back to HP and they replaced the whole unit under the warranty
agreement. I'm afraid to use it now, though I'm sure the chance of a repeat
performance is low. Has anyone else out there had this kind of experience?
Is this a common thing for thermal printers?
--
Steve Scherf
steve@Altos.COM ...!{sun|sco|pyramid|amdahl|uunet}!altos!steve
These opinions are solely mine, but others may share them if they like.kenw@col.hp.com (Ken Wyatt) (12/15/90)
I have used an "A" model for quite some time without any trouble.
rrd@hpfcso.HP.COM (Ray Depew) (12/18/90)
Steve Scherf tells a spooky story: > [ The Case of the Fried Thermal Printhead ] > I sent it back to HP and they replaced the whole unit under the warranty > agreement. I'm afraid to use it now, though I'm sure the chance of a repeat > performance is low. Has anyone else out there had this kind of experience? > Is this a common thing for thermal printers? Well, speaking as a user and not as an HP employee, I think you've experienced a rare event. Thermal printheads themselves are pretty sturdy, and something like this would only happen if the control electronics inside got zapped. If you had disassembled your printer (which obviously you didn't for good rea$on$), you would probably have seen some discolored components or circuit traces. (Well okay, maybe not...) I own two of these printers and have access to several others, and they've survived lots of abuse without ever showing this problem. However, I can understand your not wanting to use the printer again. I have the same irrational fear of placing my 48 in server mode and controlling all my file transfers from the PC. Nothing bad has happened to me yet; it's just a lot more comforting to do it all from the 48's keyboard. Like I said, totally irrational. Regards Ray Depew IC's by Bill and Dave rrd@hpfitst1.hp.com
rrd@hpfcso.HP.COM (Ray Depew) (12/18/90)
What I MEANT to say: > rare event. Thermal printheads themselves are pretty sturdy, and something > like this would only happen ... " ... if the control electronics inside got zapped ALSO." A dead short on ^^^^ the right control ckt. would send enough voltage to the printhead to fry the paper and the platen. And the printhead. But I think you're pretty safe now. People don't usually get struck by lightning twice. Regards Ray Depew IC's by Bill and Dave rrd@hpfitst1.hp.com ----------
daver@ECE.ORST.EDU (Dave Rabinowitz) (12/19/90)
In article <4491@altos86.Altos.COM> steve@altos.com (Steve Scherf) writes: >and print and never have to replace a ribbon or ink cartridge. Then one >day (when it was a mere two weeks old) I turned it on, and POOF! A little >column of smoke rose from the area of the printing head. When it attempted >to print what I had sent to it, it just made a bunch of black streaks on the >paper. The spot on the paper where the head had been at rest had a hole burned >through, and the rubber platen behind it had melted. That head must have >gotten really hot to do that. The bubbled and warped plastic on the head >itself was testimony to that. The head normally operates on a very low duty cycle (it's pulsed on for a very short time and then remains off until the next column). If a dot is left on for more than a few seconds it will self-destruct (it gets really hot). The CPU runs directly off the batteries and if the battery voltage dropped low enough to lock up the CPU while a dot was on the dot would be dead, so there is a low-voltage detector which resets the CPU (clearing the dot outputs) before the voltage gets low enough to cause a problem. In your case it sounds like there was a short in one of the inputs to the head driver (a separate current driver chip plus a transistor for the eighth dot - the driver chip was designed for the 7-row non-graphics printer version) was shorted to a value which caused it to be permanently on. Since it didn't happen until after you had the printer and had used it successfully it might have been caused by a scrap of metal which somehow got into the unit.
akcs.joehorn@hpcvbbs.UUCP (Joseph K. Horn) (12/21/90)
Hey, all; remember the PPC hey!days, and how we got the HP-97 to print pseudo-graphics using non-normalized numbers? But remember, there was a danger of sending the right combination of bits which would turn on a dot and leave it on! Which, of course, immediately resulted in a puff of smoke, a very dark dot on the thermal paper (burned thru!), and one dead printhead dot. This sort of printer destruction was so easily produced that HP let it be known that the HP-97 warranty did not cover damages resulting from the printing of non-normalized numbers. Notice that it required no damage to the printer's electronics or short circuit or controller crash; just the right bitstream to the printer. Could we be seeing this ancient phenomenon again? Just a thought... -- Joseph K. Horn -- (714) 858-0920 -- Peripheral Vision, Ltd. --