Lexicon LXP-5 Service Manual

LXP-5 Service Manual
Performance
Verification
If a switch position combination triggers a failure indication, keep the switches
in the failing position. With an oscilloscope set to measure DC levels at 2V/
cm, probe pin 1 on SW2, SW3,and SW5 and compare. When all switches are
in the same position they should all have the same level. Repeat this
procedure on pins 2 through 6, noting any dissimilarities, if one out of the three
switches is at a different level, suspect the switch or the signal line’s
associated pullup resistor (RP1 or RP2).
CAUTION: RUNNING THIS TEST WILL DELETE THE CONTENTS OF
ALL USER REGISTERS.
This diagnostic program clears the contents of the master processor’s static
RAM, and runs a series of write/read tests on the RAM. Since this program
will delete any stored user registers, a series of steps are required to activate
this procedure. The steps are as follows:
1 Set FUNCTION to EDIT A; set SELECT and ADJUST to MIN. Press
LEARN. (The LEARN LED will flash red once.)
2 Set SELECT and ADJUST to 2\ set FUNCTION to BYPASS. Press
LEARN. (The LEARN LED will flash red once.)
3 Set FUNCTION to EDITC, and press LEARN. (The LEARN LED will flash
red once.)
4 Press LEARN once again to run the test.
If the LEARN and OVLD LEDs flash alternately at any time during the first
three steps, the procedure is not being performed correctly and needs to be
reselected by turning FUNCTION to EDITA and pressing LEARN. When the
procedure is followed correctly, and the test has been successfully com¬
pleted, the LEARN LED will flash continuously. Alternate flashing of the
LEARN and OVLD LEDs after step 4 indicates test failure. If failure occurs,
the Slave and Master RAM ICs (U20, U17) are suspect. If the Slave RAM is
failing, run the Slave tests to determine whether failure is caused by the
support circuitry or the Slave RAM 1C.
This test checks the non-volatile area of RAM used by both the master and
slave processors by comparing a character string stored in ROM to a
character string stored at a specific address in RAM. When the two differ, a
failure will result, indicating RAM storage failure may have occurred. Pressing
the LEARN button a second time will copy the character string from ROM to
RAM and perform the test again. A second failure indicates a possible RAM
hardware malfunction or defective Battery Backup circuitry. If the test passes
on the second try, power down the unit for at least 10 seconds, then power
up in Diagnostic Mode and rerun this test.
Clear RAM test
(Edit A )
special procedure required
Non-volatile Memory test
(MULTI;
Note: This test will fail if the Clear Ram test has been performed
since the last copy of the character string from ROM to RAM.

Lexicon LXP-5 Specifications

General

Brand	Lexicon
Model	LXP-5
Category	Recording Equipment
Language	English