close@cacilj.UUCP (Diane Barlow Close) (06/04/89)
Roger Hunen (awinfhah@hmarl5.bitnet) writes:
-> This may be old news, but since I haven't seen the issue here for several
-> months, I'll (re)start it. If you have a NEC P2200 printer connected to
-> your ST *without* modification,
->
-> **** DISCONNECT IT NOW ****
->
-> The P2200 has 1k pull-up resistor on the Centronics port. This may eventually
-> kill the sound chip in the ST. (1k pull-ups may cause up to 5mA of sink
-> current, whereas the sound chip can only handle 1.6 mA.)
I've been having some strange problems with my recently-purchased DeskJet
Plus, and I suspected a similar problem with resistors. I wrote Dave Neff
of H.P. (neff@hpvcla) and he wrote back:
-> I showed your latest letter to the DeskJet+ electrical engineer and he
-> said we have a 1K pullup resistor on the strobe line and 2.2K pullup
-> resistors on each data line. The 2.2K resistors result in about 2ma
-> of current and the 1K about 5 ma. So I might be concerned if I
-> were you.
->
-> If this problem is confirmed our support position may have to be
-> DeskJet+ should not be used with Atari STs. How can we be sure
-> there really is a problem?
So, how can we be sure there *is* a problem? This looks serious. Any
DeskJet Plus owners might want to heed Dave Neff's warning and only use the
serial port for printing (or buffer your lines!).
I don't know if this is a problem with (plain) DeskJets or not--can anyone
confirm/disprove it?
:-( :-( :-( :-( :-( :-( :-( :-( :-( :-( :-( :-( :-( :-( :-(
--
Diane Barlow Close
{uunet, crash, ucsd}!cacilj!close
close@cacilj.uucp
Free Canada -- Trade Mulroneyneff@hpvcfs1.HP.COM (Dave Neff) (06/07/89)
DeskJets have the same 2.2K data pullup resistors and 1K strobe pullup resistor as the DeskJet+. Has anyone using a DeskJet ever had damage to their sound chip as a result? I don't want to tell our support people about this alleged problem until it is confirmed to be a real problem. Does someone have a contact inside Atari who could explain the real electrical characteristics of the "sort of" parallel port on the ST (if it was a "real" parallel port the pullup resistors and resultant current levels would not be a problem). Dave Neff hplabs!hpvcfs1!neff
obryan@gumby.cc.wmich.edu (Mark O'Bryan) (06/14/89)
In article <1024@cacilj.UUCP>, close@cacilj.UUCP (Diane Barlow Close) writes: > > I've been having some strange problems with my recently-purchased DeskJet > Plus, and I suspected a similar problem with resistors. I wrote Dave oeff > > ...some material deleted... > > I don't know if this is a problem with (plain) DeskJets or not--can anyone > confirm/disprove it? My brother has been using a (plain) DeskJet on his 520 ST for about a year now, and has never had any problems at all. He loves it. -- Mark T. O'Bryan Internet: obryan@gumby.cc.wmich.edu Western Michigan University Kalamazoo, MI 49008