Lexicon PCM 42 - SECTION SEVEN IN CASE OF DIFFICULTY; UNIT WILL NOT POWER UP; IMPROPER DISPLAY ISSUES; NO AUDIO OUTPUT

7.1 GENERAL
Before you attempt to verify whether there is a gen-
uine problem with the unit, it is important that you
understand the operating and installation information
presented in this manual.
WARNING
ALL SERVICING OF THE PCM 42 SHOULD BE
PERFORMED BY QUALIFIED SERVICE PER-
SONNEL. THERE ARE HAZARDOUS
VOLTAGES LOCATED UNDER BOTH THE
TOP AND BOTTOM COVERS OF THE UNIT.
TO AVOID ELECTRICAL SHOCK, REMOVE
THE POWER CORD PRIOR TO REMOVING
COVERS. SERVICING PROCEDURES CON-
SISTENT WITH GOOD SAFETY PRACTICES
SHOULD BE USED AT ALL TIMES.
7.2 UNIT WILL NOT POWER UP
if the PCM 42 will not power up, first check the AC
line cord to ensure it is securely plugged into the PCM
42 and the service outlet. Then verify the service outlet
is “live” and that the voitage is correct for the PCM 42
(use a voltmeter, neon test light, or a common lamp). If
correct voltage is present, unplug the PCM 42, and refer
the problem to a Lexicon authorized service technician,
or return the unit to Lexicon (see Section 7.5).
7.3 UNIT POWERS UP, GIVES IMPROPER
DISPLAY
The numeric display of the PCM 42 should always
read eithér the delay time in milliseconds or the frac-
tional ratio of the clock output period to the delay time.
An incorrect display indicates a problem with the
microprocessor section of the unit. Refer the problem to
a Lexicon authorized service technician, or return the
unit to Lexicon.
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SECTION SEVEN
IN CASE OF DIFFICULTY
7.4 UNIT POWERS UP, BUT WILL NOT PASS
AUDIO
Check Cables
Check all audio cables to be sure they are securely
plugged into the proper jacks. If the connections are
good, check the cables themselves. Look for continuity
and shorts between conductors while flexing the cable
to check for intermittent contacts.
Check Other Sound Equipment in System
if all cables are good, the next step is to check the
rest of the equipment in the sound system to ensure it is
indeed operating properly. Unplug the PCM 42 MAIN
OUTPUT cable at both ends, and set it aside. Then
unplug the cable from the PCM 42 INPUT, and instead
connect it to the point which had been fed by the PCM
42°s output. This bypasses the PCM 42 entirely. If the
audio now passes through the sound system, the pro-
blem resides in the PCM 42: if audio still does not pass,
there is a problem elsewhere, and probably not in the
PCM 42.
Check PCM 42 Control and Switch Settings
Be sure the rear-pane! OUTPUT LEVEL control is set
properly. in its full counterclockwise position, this con-
trol is capable of completely shutting down the main
output. Also, be sure the unit is not in INFINITE
REPEAT mode, since it may be ‘‘holding’’ no signal at
all.
7.5 RETURNING UNITS FOR REPAIR
if it becomes necessary to return a PCM 42 for ser-
vice, bear in mind that Lexicon assumes no responsibil-
ity for units in shipment from customer to factory
whether or not they are in warranty. It is important,
therefore, that shipments be well packed, properly in-
sured, and consigned to a reliable agent such as UPS or
Federal Air Express. Be sure to include (inside the car-
ton) a note explaining the nature of the problem, refer-
encing any conversation with Lexicon personnel you