QSC PowerLight Series Technical & Service Manual page 22

The CMP box
The CMP box has two digital panel meters that monitor AC
voltage and current and a solid-state electronic AC fuse that
can be set to trip specific current levels from 0 to 100
amperes.
To set the current trip level, flip the trip set switch down;
the AC ammeter will then read the trip current setting. Use
the trip set knob to adjust the desired trip point, then flip
the switch up.
The BNC jack provides an AC voltage proportional to the AC
current: 100 mV RMS = 1.0 ampere RMS. This is useful in
the transformer balancing procedure because it allows the
use of an external voltmeter with finer resolution (>3 decimal
places) than the panel ammeter has.
Trip set switch up:
UP for normal solid state fuse function;
reads AC current;
Trip set switch down: DOWN
reads trip current setting
AC voltage
Adjusts trip current
of solid state fuse
0–280 VAC in
Figure 2.20. The CMP box. The variable AC outlet for
the test fixture is on the back of the box.
Important note about repaired PFC power
supply modules
After repairing a failed power supply module that had
already been calibrated before its failure, either in produc-
tion or in Technical Services, the VOUT/32 and VOUT @
idle voltages in Procedure 1 only need to be checked and
not fully adjusted, unless the measured high rail voltage is
not 191.3 volts, ±1.5 volts, for the PL 9.0 or 166.5 volts, ±1.5
volts, for the PL 6.0. If the high rail voltages are outside this
range, then the module will require full adjustment and
calibration.
20
Trip set switch: Indicates that the
solid state fuse
to set solid state fuse trip circuit has tripped
AC current
sample for
external DMM
100 mV = 1.0 A
Press switch
down and back
up to reset the
solid state fuse.
from Variac
Gate drive cable
Figure 2.21. The gate drive cable for the MOSFETs.
Disconnect it here for the V
OUT
9. Connect DMM #1 to one set of the parallel DC V
on the back of the fixture. Connect DMM #2 to the controller
card, with the ground or reference lead on the tab of U8, a
+12V regulator, and the hot lead on the left leg of capacitor
C34. On the board, this point is labeled "VOUT/32."
10. Note: this step is optional because the replacement diodes
specified in this bulletin do not have the leakage problems
that many of the original fast diodes had. Through a differen-
tial probe, connect an oscilloscope input between resistor R31
(labeled "OSC") and ground; this will allow you to view the
output of the diodes to see if any are leaky.
11. Turn the fixture power switch on. Turn up the Variac gradually
until DMM #1 reads 190 volts DC (for the PL 9.0) or 166 volts
(for the PL 6.0). You don't need to measure the AC voltage
from the Variac yet.
12. Adjust VR1 to obtain a reading on DMM #2 of 5.94 volts DC
(for the PL 9.0) or 6.20 volts DC (for the PL 6.0).
13. Flip the I switch down. If the LED indicator next to the
SET
switch lights green or orange, I
should be rejected for controller board replacement or repair.
14. Turn down the Variac all the way. Turn off the fixture's AC
switch. Unplug the external supply's AC line from the Variac.
15. Set the I and V /32 switches down . Remove DMM #2's
SET OUT
leads from the controller card.
16. Wait a few seconds for the capacitors to discharge and DMM
#1's voltage reading to drop to 60 volts or less.
Procedure 2 of 5: Adjusting idle voltage
1. Re-attach the gate drive cable on the power supply module.
Also, disconnect the five DC rail output wires on the right end
of the module from the lower barrier strip and attach them to
the corresponding screw terminals on the upper barrier strip.
Make sure the screw connections are tight and secure.
2. Turn the fixture's AC switch on and turn the Variac up to the
appropriate AC voltage: 120 volts AC for a 120V module, or
230 volts AC for a 230V module. The power supply will turn
on and begin to draw current when the AC voltage reaches
about the halfway point.
3. Adjust VR4 to obtain the a reading of 191.3 volts DC (for the
PL 9.0) or 166.5 volts DC (for the PL 9.0) on DMM #1.
procedure.
terminals
OUT
is good; if red, it is bad and
SET
QSC Audio Products, Inc.
TD-000083-00