Zenith Z-100 PC series Service Manual page 288

Page
4.2
Troubleshooting
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Seriallnput/Output
Power-up diagnostics do not check serial 1/0 signals. If trouble is experi­
enced with the serial port, several things must be checked before assum­
ing component or card failure. Most suspected problems with serial 1/0
signals are not hardware related, but originate from incorrect software
or incorrect protocol for serial communications.
The 1/0 portion of the Disk-Based Diagnostics Program (a purchase op­
tion), may be used to locate a problem. Refer to Chapter 4, "liD Port
Diagnostics" of the Disk-Based Diagnostics manual for more information.
If the diagnostic tests indicate no problem, proceed with the following 5
steps in the order indicated.
1.
Check for the correct serial cable. The liD port is a DTE output
device and cannot accomodate the HCA-10, 11, or 12 cable as
indicated in ZDS literature for this computer. A "null modem" cable
must be used which is supplied under the HCA-50, 51, and 52
catalog numbers.
2. If the correct cable is being used, run the CONFIGUR utility (supplied
with MS-DOS) and reconfigure the output port to accomodate the
protocol required by the serial device.
NOTE: MS-DOS normally routes the printer through the parallel port.
If a customer is attempting to use a serial printer, CONFIGUR must
be run before the printer will operate correctly.
3. If you are still experiencing problems with a serial device, try using
the device with another computer that is known to work. Try both
the hardware and customer's software. This should establish
whether or not the fault lies with the device, computer, or software.
4. If none of the preceding checks have resulted in positive identifica­
tion of the problem, replace the Color VideolFIoppy Controller Card
and rerun the checks. This should isolate the problem to the card.
If the card is at fault, use Table 4.1 for checking the individual com­
ponents.
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