45
Test Procedures
L1
®
Compact Power Stand Tests
CAUTION:
The SMD integrated circuits used
on the Input / Output PCB are extremely
sensitive to ESD damage. Be sure to use an
approved and tested ESD strap that is
properly grounded to your work bench before
attempting disassembly or repair of the L1
Compact Power Stand.
Equipment Required
• dB Meter
• Digital Multi-meter
• Audio Signal Generator
• Distortion Meter
• 2 - 4 Ohm, 50 Watt Load Resistors
• Test cables, see Appendix
Note:
•
Channel 1 refers to the left Side of the
power stand input panel that has the XLR
Microphone Jack. Channel 2 refers to the
right side with the TRS (1/4”), RCA and 1/8”
input jacks.
•
When testing Channel 1, turn Channel 2
Volume to Min. When testing Channel 2, turn
Channel 1 Volume to Min.
Note:
The following tests will check the
performance of the Input PCB, I/O PCB and
the Output PCB assemblies
1. Channel 1 LED/Gain Test
1.1
Using an XLR cable, apply a balanced,
1kHz, -50dBV (3.16mVrms) sine wave to the
channel 1 XLR microphone input. Adjust the
volume control so that you measure the
-50dBV output level at the 1/4” balanced line
output jack on the back of the power stand.
1.2
While measuring the output level at the
1/4” balanced line output jack, increase the
volume level on the channel 1 input and
verify that the LED functions, and record the
levels at which the trim LED’s color states
change. The LED should turn green at
-30 +/-2dBV (31.6mVrms), and red at 0 +/-2
dBV (1Vrms).
2. Channel 2 LED/Gain Test
2.1
Set the channel 2 ToneMatch switch to
the OFF position (down).
2.2
Using an balanced TRS cable, apply a
balanced, 1kHz, -50dBV (3.16mVrms) sine
wave to the channel 1 balanced 1/4” input
jack. Adjust the volume control so that you
measure the -50dBV output level at the 1/4”
balanced line output jack on the back of the
power stand.
2.3
While measuring the output level at the
1/4” balanced line output jack, increase the
volume level on the channel 2 input and
verify that the LED functions, and record the
levels at which the trim LED’s color states
change. The LED should turn green at
-30 +/-2dBV (31.6mVrms), and red at 0 +/-2
dBV (1Vrms).
2.4
Repeat steps 2.2 and 2.3 for the
channel 2 unbalanced RCA and 1/8” stereo
input jacks.
3. Channel 2 Line Output Test
3.1
Set the channel 2 ToneMatch switch to
the OFF position (down). Set the channel 2
volume control to maximum.
3.2
Using an balanced TRS cable, apply a
balanced, 1kHz, -41dBV (9mVrms) sine
wave to the channel 2 balanced 1/4” input
jack.
3.3
Measure the output level at the
1/4” balanced line output jack. It should be
0dBV +/- 1dBV (1Vrms).
3.4
Measure the output level at the unbal-
anced RECORD output RCA jacks. It should
be -6dBV +/- 1dBV (0.5Vrms).
3.5
Apply a, 1kHz, -24dBV (63mVrms) sine
wave to both of the channel 2 RCA input
jacks.
