APPLE SERVICE NOTICE
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Some Macintosh Serial Ports Affect Hewlett-Packard DeskWriter Printer Operation
Overview
========
It has come to Apple's attention that some customers have been experiencing print problems when using a Hewlett-Packard DeskWriter printer and a Macintosh computer. Typically, the customer has purchased the computer and the printer at the same time. The customer connects the DeskWriter to the Macintosh printer port and configures the printer for serial mode. Usually the system works properly for several weeks or even several months; suddenly the printer will not print the selected text. When the DeskWriter will not print the selected text, the printer lights will flash, and the printer sometimes prints "Error Trap 10864".
If the cable is moved from the Macintosh printer port to the modem port, the DeskWriter prints properly; however, it may fail in a similar manner after a few weeks of use.
It is important to note that the Macintosh printer port may still be operational and may pass a diagnostic test or work normally with other print devices.
Customers have reported this when using a Macintosh II, Macintosh IIci, Macintosh IIcx, Macintosh IIfx, or Macintosh SE computer. The problem appears to be limited to a small number of these systems.
Solution
========
Both Apple and Hewlett-Packard have conducted separate investigations and have isolated the cause to a component failure on the Macintosh logic board. When this failure occurs the sensing circuit in the DeskWriter causes the printer to switch to AppleTalk mode, thereby prohibiting further communication with the computer in serial mode.
To correct the problem Service Providers should replace the logic board on the Macintosh system. Systems within the warranty or AppleCare period should be repaired under these programs. For systems outside the warranty or AppleCare period contact Technical Operations for further instructions.
HEWLETT-PACKARD ANNOUNCEMENT
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Some Macintosh Serial Ports Affect DeskWriter Printer Operation
For the past few months, Hewlett-Packard has been receiving a small number of customer reports that DeskWriter printers won't print on Macintosh computers. Typically, the customer has purchased both computer and printer at the same time. The customer connects the DeskWriter to the Macintoshes Printer port and configures it for serial mode. The system works properly for a few weeks or even a few months; then the printer does not print the selected text. The DeskWriter's lights flash, and the printer sometimes prints "Error Trap 10864." If the cable is moved to the Macintoshes Modem port, the DeskWriter works properly; however, it may fail in a similar manner after a few weeks have passed. This has occurred on Macintosh II, Macintosh IIci, Macintosh IIcx, Macintosh IIfx, and Macintosh SE computers.
Both Apple and Hewlett-Packard have conducted separate investigations and have isolated the cause to a component failure on the Macintosh logic board. We have determined that on a small number of Macintosh computers the resistances of the I/O lines degrade over time and eventually fall below the RS-422 specification. When this occurs, the sensing circuit in the DeskWriter causes the printer to switch to AppleTalk mode, thereby prohibiting further communication with the computer in serial mode.
It is important to note that the Macintoshes Printer Port may still be operational and may pass a diagnostic test or work normally with some other print devices. Hewlett-Packard's and Apple's joint recommendation is that any DeskWriter user who experiences this problem should return the Macintosh to an Apple- authorized service provider for repair, according to Apple's recommended procedures.
Apple will soon be issuing a statement (Apple's Statement is above) that further describes this problem, along with their technical recommendations. Until that time, service providers should contact their Apple Service Representative for instructions. In closing, Hewlett-Packard would like to thank Apple for their cooperation and prompt response in this matter and express our regret for the inconvenience this has caused our mutual customers.
IMPORTANT NOTES (5/95)
======================
This problem is limited to the Macintosh models listed above. If you have another model other than the one's listed above, your problem is not necessarily a hardware failure. In most cases, when you get an error message generated by the DeskWriter software mentioning that the serial port is in use, it is caused by using the serial DeskWriter printer driver, and having AppleTalk turned on.
In order to print using the serial DeskWriter printer driver, you must have AppleTalk turned off. If you need to use AppleTalk, use the AppleTalk DeskWriter printer driver.
Article Change History:
23 May 1995 - Added important notes.
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