JBL A6000GTi, Руководство по обслуживанию, Страница: 28 / 62

137159-1 Rev. 1 A6000GTi Service Manual

2003 Crown Audio, Inc.
Maintenance 4-9
4.4. Troubleshooting
As mentioned earlier, the three steps to effective repair are: Determine the symptoms;
identify the cause of the symptoms; repair the unit to eliminate the cause.
Please troubleshoot based on the order listed below.
4.4.1. Power Supply
Caution: Before plugging the 6-conductor cable into the audio
section, always make sure the voltage on the outer pins of the cable
and on the audio section is less then 5 volts. Failure to do so will
result in irreparable damage to the main board.
The power supply is equipped with 5 LED’s to indicate fault modes and aid in
troubleshooting. These LED’s are E1-3, and E5-6 on the power supply circuit board.
FAULT MODES

Battery OV (E1) Voltage greater then 16V

Battery UV (E6) Voltage less then 10V

LVPS POS (E3) Low voltage power supply positive no good

LVPS NEG(E5) Low voltage power supply negative no good

ILIM (E2) Power supply over current or audio section fault
Battery OV: This LED (E1) indicates the battery voltage is greater than 16V. Check the
battery voltage. The circuit should shut the amp down with approximately 16.0V and turn
back on with approximately 14.5V.
Battery UV: This LED (E6) indicates the battery voltage is less than 8V. Check the
battery voltage. The circuit should shut the amp down with approximately 8.0V and turn
back on with approximately 9.4V.
LVPS+/-: Check voltages at L1 & L4 on the power supply PWA. They should be plus &
minus 24 volts respectively. If not, check for shorts to ground. Disconnect the ribbon cable
and the 6-conductor cable from amplifier and recheck voltages. The negative voltage will
drop to approximately -50 volts when the amplifier is disconnected, which is harmful to the
output capacitor on the low voltage power supply (LVPS), so this measurement needs to
be made quickly. Plug the ribbon cable back into the amplifier.
If the plus and minus voltages were ok, the problem is in the amplifier, but if they were not,
the problem is on the power supply board. If the +24 volts was low, remove the 15 volt
regulator (U6 on Power Supply PWA) and check the voltage at L1, if the -24 volts was low,
remove the -15 volt regulator (U7 on Power Supply PWA) and check L4; if the voltages are
normal, check the regulators (U6 and U7) for shorts to ground on their outputs. If they are
not shorted, check individual IC’s for undo heating or current draw.