Epson PX-8 - Page 215

REV.-A
(5) Keyboard error message
I
LJ I'll.:. :::. ;"i (:l!~; C: i: I:::: .... I ;.1
! '" i.::." L.: l ... ; L.! 1:::. i.::. :< I ;.: C) r.:
Fig. 5-46
Key entry code mismatch - a key code other than the specified one was input. Up to five key
entry retrials are allowed.
(6) Barcode
error message
Fig. 5-47
Barcode pattern read failure.
Unit Level Troubleshooting
When trouble-shooting a faulty unit, first find the entry routine for that unit from the entry table.
In such a case
where there are more than one symptom is observed and symptoms vary during
the course of troubleshooting, make it a practice to enter the troubleshooting procedures accor-
ding to the symptom that occurred first.
Notes on using
the flowcharts
1) The troubleshooting flowcharts do not necessarily include all information required for trouble-
shooting such as check modes, etc. Thus, the flowchart context and trouble symptoms should
be closely examined.
2)
If the troubleshooting flowchart instructions lead you into a loop or to the end of a procedure
and
the problem is not resolved, refer to the schematic drawings or proceed by troubles shoo-
ting according to the following procedure:
Step 1 : Replace
the faulty unit with a good one and make sure that the faulty unit is really mal-
functioning.
Step 2: If the problem is difficult to reproduce or occurs so briefly that it is hard to examine the
symptom, vary the supply voltage according to the following instructions:
(a) Disconnect the battery from the battery connector CN2.
(b) Prepare a variable (0 - 10) DC voltage regulator and make sure that the output is
turned off.
(c)
Connect the regulator to the CN2 connector in place of the battery.
(d) Adjust the regulator output voltage to +5V.
(e) Turn the regulator output on.
After the above setup is completed, vary the regulator output in a range from 4.8V to 6.0V and ex-
amine
the unit operation at each voltage level. If this voltage margin test is successful maintain
the voltage and proceed with troubleshooting, using tne check-out procedure and trouble-
shooting flowchart.
5-14