General Maintenance
Audio Power-Up
Diagnostic Failure
It is sometimes dif
fi
cult to isolate the root cause of audio problems. Most audio
problems are due to faults on the audio board, but the audio board communicates
with the main board, so in some cases the problem may be there as well.
Audio Power-up Diagnostic Detailed Information.
The Power-up Diagnostic does
the following:
Reads all of the AES decoder internal registers and veri
fi
es that what is read
is correct
Reads all of the D/A internal registers and veri
fi
es that what was read is correct
Performs an active-bit test on the A/D output clocks
Checks the serial EEPROM to see which of the analog inputs have been
calibrated
Tests the Audio DSP/FPGA interface
The main CPU detects if the DSP heartbeat fails. This condition will be
shown in the diagnostic log
For audio boards, not all errors are reported by the power on diagnostics.
Therefore, if you are detecting a loss in audio functionality, check the diagnostic
log for any reported audio errors. If any errors are found, perform the following
procedure to narrow the problem to either the audio board, the main board, or
the connection between them.
1.
Prepare a test oscilloscope with the following settings:
Control
Setting
Vertical Scale
2.00 V/div
Horizontal Scale
5.00 µs/div
2.
If the diagnostic log contains an entry that reads
Fail Audio DSP Self Test
fpga
, do the following substeps:
a.
Check audio board DS0820, the FPGA programmed indicator in the Main
board power supply test points and LEDs. (See Figure 3 on page 35.).
If this LED is off, skip to step b; otherwise probe pin 34 of connector
J26 of the Main board during the boot sequence. If the signal on the pin
toggles, replace the main board; otherwise, probe pin 34 of J200 on the
audio board. If the signal toggles on pin 34, replace the cable; otherwise,
replace the audio board.
b.
Probe pin 33 of J26 on the main board during the boot sequence. If the
signal does not exhibit a low-to-high transition, replace the main board. If
the signal does transition, check pin 33 of J200 on the audio board. If the
signal does not toggle on pin 33, replace the cable.
30
WVR7200 Waveform Rasterizer Service Manual
