Lexicon LXP-5 Service Manual

Performance
Verification
Lexicon
Test Programs, cont'd.
Footswitch test
(Chorus;
Audio Test Loop
(Delay;
runs continuously
Exit to System
(Pitch;
ROM test
(Useri;
Master RAM test
(User 2 ;
Master Address test
(User 3 ;
Master Interrupt test
(User 4 ;
Performance of this test requires a toggling off/on or momentary contact
footswitch with an appropriate 1/4” tip/sleeve plug connected to the
FOOTSWITCH jack on the rear panel. If a footswitch is not available, a 1/4”
shorting plug may be used.
The OVLD LED will light to indicate that the footwitch is OFF (or that nothing
is plugged into the footswitch jack). When the footswitch is ON (or the shorting
jack is inserted) the OVLD LED will turn off. If this test fails, check footswitch
hardware for defects. Check also J3, R19, Cl 6, CR8, CR7, RP2 and U19.
This diagnostic program tests the converter circuitry audio specifications by
producing a digitally processed output signal which is identical to the input
signal. When this test is selected, and the the LEARN button is pressed, the
LEARN LED will flash once to indicate that the program has been success¬
fully loaded. The Audio Test Loop runs continuously until another diagnostic
program is selected. If this test fails, refer to Audio Signal Tracing test later in
this chapter. Note that Audio Test Loop does not write or read from the
DRAMs in processing the signal.
This allows the user to exit Diagnostic Test mode and returns the LXP-5 to
its normal operating mode.
This test calculates the ROM checksum and compares it to the stored value.
Failure indicates that the code programmed in ROM is probably corrupt.
This tests the area of volatile RAM which is used by the master processor, by
requiring the master procesor to store and read various values. If this test fails,
check Master RAM (U17), Master data and address busses, Master Z80 and
PALU11.
This diagnostic program performs an address test as well as a test of all areas
of volatile RAM used by the master processor. The test requires the master
procesor to store and read various values in this area of RAM. If this test fails,
check Master Ram and associated hardware, as well as Slave RAM, Master/
Slave interface and Lexichip WCS. This test can be used in conjunction with
the Slave RAM test and other Slave tests to isolate the specific hardware
problem.
This test checks the interrupt timing of the master processor by comparing it
to coded timing loops. Failure indicates a problem in the Interrupt Timing
circuitry (U13, U1), or the Lexichip WC/ signal line.
2-6

Lexicon LXP-5 Specifications

General

Brand	Lexicon
Model	LXP-5
Category	Recording Equipment
Language	English