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7.4.5
Power-on Troubleshooting Using the LED's.
WARNING:
If the three input fuses are OK, then reconnect the main AC input power to the cabinet.
LV Supply (CI P/N 7003-702):
Turn the main breaker on and check green LED DS2 and DS3 on the system interface board.
Both LEDs should be lit indicating the +/-19Vdc and +/-15Vdc supplies are OK.
If one or both of the LEDs is not lit, then there is something wrong with the LV power supply and
it will have to be serviced.
Oscillator (Front Panel):
If LV supply appears good, then program 150Vac on the low range and connect a DMM to TP2
(phase A) on the system interface board with the low side of the meter connected to TP1. There
should be a 2 – 3-volt rms signal present on TP2.
AC power module (CI P/N 7003-402-1):
If the oscillator drive signals are present on the system interface board, connect the DMM to
brass terminals 5 & 6 located near the bottom of the power module. Program 100 Volts.
There should be about 100Vac between terminals 5 and 6. If no voltage at all is measured it is
possible that the AC power stage inside the module has failed and it will be necessary to remove
the power module from the chassis for closer inspection.
WARNING:
To remove the power module, proceed as follows:
1. Disconnect the 7 wires going to the brass terminals on the lower front panel of the module.
Label the wires so they can be reinstalled correctly later.
2. Remove screws securing the upper and lower straps holding the module in the chassis slot.
3. Remove the 50-pin ribbon connector at J50.
4. Carefully slide module outward and lift out of cabinet. Use caution, module weighs 66 LBS
(30Kg).
5. With the power module out of the cabinet and lying flat on a bench, remove the screws on
the bottom and sides of the cover as seen from the front when module is installed normally.
6. Inspect the three IGBT transistor modules Q1, Q2 and Q3 for any visible damage.
7. Using an ohmmeter check the 30A fuses on the positive and negative side of the power
distribution board that connects the four amplifier modules to the DC bus. If any of them are
open, then one or more of the amplifier sections has a damaged device on the heat sink
assemblies and the power module assembly will have to be serviced.
7.4.6
Other No Output Conditions
If one or more outputs is gone, it may be caused by an amplifier failure. Amplifier failures can
either be input (PFC) or output related (Amp). To determine if this is the case, the cover of the
MX15
Do not touch any parts inside the unit during this test as they
will be live and dangerous. Always wear safety glasses.
Wait 10 minutes for all internal capacitors to discharge.
125
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