Sony KDS-R50XBR1 Training Manual page 82

Check Vottage Supply to
S1 & S2 boards
CN2303/ pins 7 & 11
Check CN2303/pins 7 & 11 on both the S1-Board and the S2-Board for
the presents of 5V.
Check CN6900/pins 4 through 6 on the C-Board for the presents 6.5V.
Once again, if the voltages are missing the defect exists in the power
supply (reference Flowchart B for Power Supply Troubleshooting
procedures).
If the power supplies are present at all the boards the troubleshooting
process comes down to a process of elimination by substituting know
good boards.
Substitute the boards in the following sequence for the most efficient and
cost effective results.
1) S1-Board
2) S2-Board
3) Optical Block (includes C-Board)
4) ASU/DSU Assembly
TVP-21
Check Voltage
Supplies to C-Board
CN6900/pins 4-6
4. Protection Circuits
79