Tektronix WFM8200, Service Manual

Page: 55 / 85

General Maintenance
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 DS511, the FPGA programmed indicator in the Main
board power supply test points and LEDs. (See Figure 4-1 on page 4-20.).
If this LED is off, skip to step b; otherwise probe pin D21 of connector
J641 of the Audio board (the connector to the Main board) during the
boot sequence. If the signal on the pin toggles, replace the main board;
otherwise, replace the audio board.
b. Probe pin D20 of J641 on the audio board during the boot sequence. If the
signal does not exhibit a low-to-high transition, replace the main board.
c. Probe pins A11 and B11 of connector J641 during the boot sequence. If
the signal on either of these pins does not toggle, replace the main board.
d. Probe pin D19 of J641 on the audio board during the boot sequence. If the
signal does not exhibit a low-to-high transition replace the audio board.
e. If all signals in a through d are correct replace the audio board.
WFM8200 and WFM8300 Waveform Monitors Service Manual 4–15