[comp.sys.mac.hardware] DeskWriter strange behavior

jhansen@convex.com (James Hansen) (03/26/91)

In <1991Mar25.233916.21520@agate.berkeley.edu> bclee@.berkeley.edu (Bob C. Lee) writes:
>	If it's any help, I've got a IIci running 6.0.7 and DeskWriter
>	driver 2.1.  80MB HD 80MB RAM.
			     ^^^^^^^^

>	So, what do you think is the problem?

Maybe it's the excess memory you have in your machine!! :-)

--
"Two guys, one cart, fresh pasta; you figure it out"
				-- Suzanne Sugarbaker (Designing Women)
jhansen@convex.com
(214)497-4802

neff@hp-vcd.HP.COM (Dave Neff) (03/27/91)

Regarding the DeskWriter 10864 Error Trap:

You have run into the infamous faulty resistor pack problem on your
Mac IIci.  There is a "deglitch" circuit on both the printer and modem
ports that use some resistor packs that can degrade over time.  The
DeskWriter "sees" the faulty resistor pack as a LocalTalk isolation
transformer and comes up in AppleTalk mode, and then gets confused by
the serial data.  Although the DeskWriter gets very confused when
the resistor pack fails, if you were to try to use your printer port
on a LocalTalk network I would expect you to get a fairly high error
rate due to the resistor pack problem.

The solution is to get your mother board fixed on your IIci.  I would
hope your Mac is still under warrantee -- if so, Apple should cover it
(I can't speak for HP, let alone Apple however).  Otherwise you can
just keep using the modem port to print -- but its resistor pack might
fail over time as well.  The DeskWriter does not cause this failure,
its just that is automatic AppleTalk/serial sensing circuit reveals
the problem.  Its my understanding the Apple has changed their process
and is using different resistor packs that don't have this problem,
but I have just heard this 3rd hand.  I also heard that HP used to use
the same resistor packs in some of our LaserJet printers until we also
started having them fail over time.

I have no idea of what Apple's policy is on Macs out of warranttee.
A board level replacement of the resistor packs (replace the ones on both the
modem and the printer ports) shouldn't be too hard, but you want to be
sure to use the right parts :-).  Fortunately, most of the resistor packs
fail when the Mac is under warantee, but the customer might not notice
it until he hooks his Mac up to a DeskWriter or possibly a LocalTalk
network (and on LocalTalk he might just get poor performance).  Most
modems and RS-232/422 printers don't get confused about the resistor
pack problem -- although the interface is out of spec when the resistor
packs fail.

If you have more questions about this problem call our printer support
line at (208)-323-2551.  I am not a support person but I was involved
in diagnosing the problem so I know something about it :-).

Dave Neff
neff@hpvcfs1.HP.COM

long@mcntsh.enet.dec.com (Rich Long) (03/27/91)

In article <1991Mar25.233916.21520@agate.berkeley.edu>, 
 bclee@.berkeley.edu (Bob C. Lee) writes...
>	and ready lights blinking sequentially.  Oh, and before everything
>	stopped, a page came out with this line on the top of it.
> 
>		10864 Error Trap

This problem sounds like one I recently heard about, in which the Macintosh
 serial port does something to make the Deskwriter think that it is in
 Appletalk mode. Apparently, other peripherals may function OK. Switching to
 the other port may help, but only temporarily. The fix is to swap the Mac's
 logic board (nice, eh?). According to what I was told, the problem affects a
 "small number of machines", including SEs and IIcis. 

 If your machine is in warranty or Applecare, no sweat. If not, your dealer is
 supposed to call "Apple Technical Support" (who will probably refer the
 dealer to HIS dealer ;-). 

 Two questions:

 How old is your Mac?

 Have you tried running in Appletalk mode (I'm just curious).

 Good luck!

Richard C. Long * long@mcntsh.enet.dec.com            * Selfware:If you like
--------------- * ...!decwrl!mcntsh.enet.dec.com!long * this program, send
A First Edition * long%mcntsh.dec@decwrl.enet.dec.com * yourself five bucks!