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4. RA-3/3A Shutdown and Self-Diagnostics
Chapter 4 - RA-3/3A Shutdown and Self-Diagnostics
Overview
Another new feature introduced in the RA-3 Chassis is self-diagnostics capability. By utilizing the timer LED on
the front panel, it can be flashed in sequences when a failure occurs to assist in troubleshooting. It works rather
well in most situations, but can also mislead the technician. The unit will also store these failure events into the
NVM IC for viewing and these can be called up by pressing “display” “5”, volume down” and “power”. This page
is only useful for troubleshooting intermittent problems since if cannot be displayed if the unit is going into
shutdown or video blanking. For a more detailed description of the shutdown circuitry, refer to training manual
TVP-10 (P/N TVP100100).
Below is a sample of the diagnostics page:
Self Check
2:
+B OCP
000
3:
+B OVP
000
4:
V Stop
000
5:
AKB
000
6:
H Stop
000
8:
Audio
000
101:
WDT
000
The numbers on the left indicate how many times the timer LED flashed, which designates the probable cause of
the shutdown. The flashes on the LED will occur at one second intervals, followed by a three second separation
period and repeat again. The numbers at the extreme right indicate how many times the problem occurred up to
999 events. You can see why this is beneficial for intermittent troubleshooting. It is always a good idea to clear
the events before exiting and that can be done by pressing “8” and “enter” on the remote. This is not the same
as pressing these buttons in the service mode. It will only clear the events and not reset customer defaults.
Beware that the service manual instructs you to enter the service mode to clear these and that is a mistake. You
can do it right from this screen. Below is a description of each event:
+B OCP:
Excessive current on the 135V line. This is usually caused by flyback problems or secondary loads on
the line. The circuit could also be tripping for no reason. This is why you should always monitor AC current while
the unit is shutting down. It will help to determine if the problem is actually an over-current condition and more
caution can be taken when servicing the unit.
+B OVP
: The 135V line has exceeded 139 volts. Go back to the section on troubleshooting regulator problems.
V Stop:
The vertical deflection circuit has stopped operating. This indication can also occur if the high voltage
circuit fails since it supplies the +15V and –15V supply rail to the vertical output. Loads on the I
2
C data and clock
bus can also be the source of this problem.
AKB:
One or more CRT cathodes are unable to generate sufficient current to return a good feedback pulse. The
AKB detect circuit may also have failed. It is common to see multiple AKB events in the diagnostic page along
with registered HV failures. See the special section on AKB in Chapter 27 of this manual.
H Stop:
The horizontal deflection has been turned off due to excessive high voltage. This will be covered in the
deflection section.
Audio:
DC voltage has been detected on one or both of the audio out lines. The set is shut down to protect the
speakers. This is usually caused by shorted audio amp IC406.
WDT:
A communications error has occurred. The main CPU is unable to communicate with the Y/C jungle IC.
The timer LED blinks continuously at one-second intervals and as soon as 101 of them occur, a failure is registered.
