Lexicon LXP-5 Service Manual

LXP-5 Service Manual
This test checks the MIDI serial port transmit and receive functions. It requires
a5 pin DIN MIDI cable to be connected from the MIDI IN jacktothe MIDI OUT/
THRU jack located at the rear panel. The MIDI OUT/THRU switch should be
set to its OUT position (toward the MIDI jacks). This test takes approximately
5 seconds before results are displayed. Failure indicates a problem with MIDI
hardware, or UART (U3).
The following steps will isolate the problem to the component level:
1. Power down the unit and power up in the normal operating mode.
2 . Set FUNCTION to PITCH; set SELECT to MIN.
3. Connect a MIDI cable from MIDI IN to MIDI OUT and set the rear-panel
MIDI OUT/THRU switch to OUT.
4. When ADJUST is turned, a MIDI message will be sent (and returned to
the LXP-5) at each new knob position. The Master Processor should
cause the LEARN LED to flicker to acknowledge the receipt of each MIDI
signal. If it does not, there is probably a hardware error.
5. While ADJUST is turned, the serial MIDI signal can be traced through the
MIDI circuitry with an oscilloscope. A pulsed waveform can be traced from
the UARTTxD pin (U3,pin 19) to U1 pin 10, and then to MIDI output jack
J2 pin 5. The signal can then be traced on the MIDI input J1 pin 5. Check
the optocoupler output U2 pin 6 for the presence of serial MIDI data and
verify that U3 receives this signal on its RxD pin (3).
When this position is selected by FUNCTION, the specific slave test is chosen
by turning ADJUST to the appropriate position (see Table 2). Remember to
press and release the LEARN button after turning ADJUST to select a test.
Choosing any of the designated Run Ail Slave tests runs the following tests
sequentially:
Shared RAM test
Slave reset test
Slave communications test
Slave interrupt test
Slave RAM test
Master WCS test
Slave WCS test
This program will display success or failure after approximately 5 seconds. If
any test in the sequence fails, a failure indication will be displayed. In this
case,run each test individually to pinpoint the area of failure.
This diagnostic program tests the area of volatile RAM shared by the master
and slave processors. This test consists of storing and reading various values
in RAM by the master processor. Failure indicates a problem with the Slave
RAM or the Master/Slave interface. Run Master Address and Slave RAM
tests to isolate the problem.
Performance
Verification
MIDI Wraparound test
(User 5)
requires a MIDI cable
Slave tests
(User 6,)
Run All Slave tests
(User 6: MIN, 9-MAXj
Shared RAM test
(User 6: 2)
2-7

Lexicon LXP-5 Specifications

General

Brand	Lexicon
Model	LXP-5
Category	Recording Equipment
Language	English