Low B+ Error (6X) - Sony KDS-R50XBR1 Training Manual

If the spark gap does not illuminate, then the next step is to check the
380V lamp driver supply voltage from the Main Power Supply (G-Board).
Measure this voltage directly at the Lamp Driver board at the X1 connector
at the top of the board. If the 380V is missing the power supply on the G-
board is defective, replace the G-Board.
If the 380V is present then the next step is to check the Lamp-On control
voltage from the TV microprocessor (ASU-Board). You can measure
this control voltage at CN2390/pin 4 on the ASU-Board. The voltage
should initially be at 3.3V while the Green LED is flashing and then go low
to ~0.13V when the Green LED glows steady.
If the Lamp-On control voltage transitions from 3.3V to 0.13V properly then
the TV microprocessor is instructing the lamp driver to turn on. At this
point in the flowchart the lamp driver is receiving its 380V supply voltage
and its Lamp-On voltage, however, the lamp driver does not function (no
spark gap). In this case replace the Lamp Driver Board.
If the Lamp-On voltage does not go low (0.13V), then the problem is with
the TV microprocessor, replace the ASU/DSU assembly.

Low B+ Error (6X)

In most cases, a defect in the power supply output (G-board) causes
this error (6X), particularly a missing Sub 11V output.
theoretically a defective TV microprocessor output can also cause this
TVP-21
Check Supply
Voltage
At
X1 Connector
Check
Lamp-ON Voltage
CN2390/pin 4
6X Flash
Pattern
(Low B+)
error, and therefore, consider this component when troubleshooting.
Your first step in troubleshooting this error is to eliminate the TV
microprocessor as a suspect for the failure. Check for the presents of the
AC-Relay voltage at CN6502/pin 31 on the G-board. This is the switched
voltage from the TV microprocessor to turn on the Main AC relay and in
turn the Main Power Supply. The AC-Relay voltage should switch to 4.8V
immediately after the power on button is pressed.
If the AC-Relay voltage is missing this indicates a failure in the TV
microprocessor circuit on the ASU-Board, therefore, replace the ASU/
DSU assembly.
If the AC-Relay is present the next step is to verify Sub 11V and regulated
5V Main Power Supply outputs.
Check for Sub 11V at CN6502/pins 9 through pin 15.
Check for regulated 5V at CN6502/pin 6.
At this point in the process the AC power is applied and the AC-Relay
voltage has been received, and therefore, all Main Power Supply
secondary voltages should be present. If the Sub 11V and/or regulated
5V is missing the Main Power Supply is defective, and the G-board must
be replaced.
If the Sub 11V and regulated 5V are present and the unit still shuts down
(6X) then there is a defect on the ASU-Board. The most likely suspect for
failure is the D5V regulator on the ASU-Board. In this case, replace the
ASU/DSU assembly.
However,
4. Protection Circuits
Check Voltage at
CN6502/pin31
Check Voltage at
CN6502/pins 9-15
CN6502/pin 6
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