Grass Valley 8921DAC - Manual (Page 43)

8921DAC Instruction Manual 43
Service
Service
The 8921DAC modules make extensive use of surface-mount technology
and programmed parts to achieve compact size and adherence to
demanding technical specifications. Circuit modules should not be ser-
viced in the field unless directed otherwise by Customer Service.
If your module is not operating correctly, proceed as follows:
• Check frame and module power and signal present LEDs.
• Verify power at the voltage testpoints (see Figure 22 ).
Note The 8921DAC module does not use fuses. It has an electronic circuit breaker
that protects against short circuits or excessive supply current with auto-
matic restart after 150 ms. Current limits are set to 4 A on the + 12 V input
and 2 A on the – 12 V input supply.
• Check for presence and quality of input signals.
• Verify that source equipment is operating correctly.
• Check cable connections.
• Check output connections for correct I/O mapping (correct input con-
nector is used for the corresponding channel output).
Refer to Figure 5 for the location of PWR LED and Table 2 on page 13 for
proper LED indications.
If the module is still not operating correctly, replace it with a known good
spare and return the faulty module to a designated Grass Valley repair
depot. Call your Grass Valley representative for depot location.
Refer to the Contacting Grass Valley at the front of this document for the
Grass Valley Customer Service Information number.
Figure 22. 8921DAC Voltage Testpoint Locations
8214_04
GRASS VALLEY 8921DAC AUDIO DAC W/DELAY 671-6497-
Voltage Test Points
+12V
+5V
+3.3V
+2.5v
+1.2v
-12V