Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!sun-barr!ames!attctc!jolnet!swan
From: swan@jolnet.ORPK.IL.US (Joel Swan)
Newsgroups: comp.sys.atari.st
Subject: Re: REFILLING HP DeskJet INK CARTRIDGES -- a warning...
Message-ID: <1600@jolnet.ORPK.IL.US>
Date: 26 Sep 89 01:44:19 GMT
References: <890922.08325265.044109@SFA.CP6> <1716@ns.network.com> <1585@jolnet.ORPK.IL.US> <1356@blackbird.afit.af.mil>
Reply-To: swan@jolnet.UUCP (Joel Swan)
Distribution: na
Organization: Media Specialties Ltd.
Lines: 45

In article <1356@blackbird.afit.af.mil> jlong@blackbird.afit.af.mil (Jeffrey K. Long) writes:
:In article <1585@jolnet.ORPK.IL.US> swan@jolnet.UUCP (Joel Swan) writes:
:>
:>True, so far as nothing goes wrong with your printer.  However, the possibility
:>of the bogus ink clogging the pump inside your DJ is very high.  Once
[text deleted]
:
:I am going to be very surprised if anyone has really seen this happen!!
:A few moments examining the print head set-up in my Deskjet would indicate
:that the actual "jets" of the head are SEALED shut by a rubber seal (I
:guess this is the "primer tube" opening?  If this is not the case, and
:assuming that ink is supposed to collect in this "primer tube" in a liquid
:state and remain that way, how does the original HP ink perform this
:magcic??  I have been under the impression that the priming action actually
:was the result of an increased elctrical drive signal to the cartridge to
:force more ink into the jets.  Is this wrong?
:
:Would someone from HP please, at least unofffically, respond to this issue?
:
:|   Jeff Long              jlong@afit-af.mil  (ARPA net)                |

Yes and No.  My information comes from an HP publication that is circulated
internally to HP.  One of the issues was devoted to the developement of the
DeskJet, it's ink cartridge, paper movement systems, electrical systems, 
user interface systems, etc.  I am not speaking "officially" for HP.

You are right when talking about an "electrical drive signal" that ink into
the jets, sort of.  The jets get heated and force the ink to eject in rapid
succession.  

However, the pump I'm talking about is not in the cartridge, but in the body
of the DiskJet.  If you open the DJ up, you will find on the righ-hand
side, the cam and tube I'm refering to.  Each and every time the DJ begins to
print, the cartridge head wipes across a rubber wiper.  Next to this wiper
is the opening is where the cartridge rests.  This is where the tube sucks
the ink to "prime" each printing.

Like I said, the new ink may work fine, but I hear HP is developing a DJ
approved water proof ink, so I'll wait and see.

If you can get you hands on this HP circular (about 40 pages?) it makes
very interesting reading.  They really pulled off a mechanical coup with the
DJ.

Joel