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SYSTEM-l1 B SOUND CIRCUITRY TESTS
Tests of the System-lIB Sound circuitry, including the Audio Board, are
possible only after successful completion of the System-lIB Memory Chip
Test.
1.
Audio BoardTest.
A
brief check of the Audio Board (D-II581) circuitry
occurs at game Tum-on; the game reports the test results by brief sounds,
as follows: No sound
=
AudiOBoard is not operating, or a failure is
affecting the sound circuitry (broken cable: dead amplifier: etc.): 1 sound
=
system OK; 2 sounds
=
RAMproblem: 3 sounds
=
U4 problem: 4 sounds
=
UI9 problem.
If the this test did not isolate the problem, tum the Volume Control
for maximum output. Momentarily touch a powered-up AC soldering iron
on the center tap of the Volume Control.
CAUTION
DO
Nor use a soldering iron over 40 watts. Note also that cordless
soldering irons will Nor work for this test.
Hearing a low hum or a 'click' indicates that the power amplifier (Ul,
TDA2002), the Volume Control, and the speaker are operating
satisfactorily, as is the sound circuit cabling. Not hearing a sound requires
repeating the test with the Volume Control turned part way down, to
determine whether the Volume Control is faulty. Also, check the cable
connectors for proper mating, and that no broken wires affect this circuit.
Test/Dlignostlc Procedures 1-43