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Protect Malfunction
To see if HV Prot or ABL Prot are suspect check the Shutdown Log data at the Shutdown Log register. Refer to Shutdown
Log Table below.
When an HV Shutdown is indicated, check R917, R921 and D905 or, replace T501 (FBT).
Where ABL Shutdown is indicated, check the voltage T901 pin#11.
If it is higher than 0.5v immediately prior to shutdown, check connections all the way to N board. Should the voltage reach
and remain at the 0 volt level, even after the first 2.0 seconds of Power On, check D909 and 904 or check White Balance.
Bit Register value
bit7
bit6
bit5
bit4
bit3
bit2
bit1
bit0
7. Protection Circuitry Overview
Overview
The D99 chassis was developed with protection circuits other than HV/ABL.These protection circuits are controlled by
Microprocessor (IC901);
- Thermal Shutdown: Activates when S-Cap Switch in FET are broken (especially Q513 and Q514).
- V Scan Shutdown: Activates when Vertical Deflection signal is absent or of insufficient level or of a distorted nature.
- H Scan Shutdown: Activates when Horizontal Deflection signal is absent or of insufficient level or of a distorted nature.
Troubleshooting Hints
S Cap Switch Shutdown
In the event of failure of any S-Cap Switching FETs, the Microprocessor detects temperature of FETs (Q513 and Q514) by
TH501 and goes into shutdown mode. For these conditions, refer to the section of H Linearity Circuit.
Vertical Scan Shutdown
If the V FLY feedback at pin #19 the Microprocessor doesn't get pulse around 1.5 second, a Shutdown will be initiated.
Power Supply problems may also produce a similar type failure. For these conditions, refer to the V Deflection Circuit or
the Power Supply section.
Horizontal Scan Shutdown
If the H BLK feedback at pin #32 of the Microprocessor doesn't get pulse around 500mSec, Shutdown will be initiated.
Some power Supply problems may also produce a similar type failure. For these conditions, refer to the H Deflection
Circuit or Power Supply sections.
8. Vertical Deflection Circuit
Theory of Operation
The negative input of amplifier IC401 is driven by VSAW signal generated by Jungle IC902 pin #8. The positive input of the
amplifier is Vref Signal generated by IC701 (Convergence IC) pin #5. VSAW is centered on 5. 0V, and sawtooth waveform
that controls VSIZE. Vref is a reference that is compared to VSAW at IC401. VCENTER is controlled by the shift of VSAW.
IC401 serves as a transconductance amplifier (it amplifies a low level voltage into a high level current) for VSAW and the
DC difference between VSAW and Vref. The current gnerated by IC401 is feed to the Vertical Deflection Coil. At the return
point of the Vertical Deflection Coil the current flows through R403 and R405 which generates a voltage across them which
is feed back to the amplifier via R404.
V FLY is generated by flyback pulse generated at pin 3 of IC401. If the flyback generation at IC401 does not work, then the
SHUTDOWN LOG TABLE
Shutdown Mode
128
N/A
64
N/A
32
Thermal
16
ABL Shutdown
8
HV Over
4
HV U Shutdown
2
No Vertical Scan
1
No H Scan
-
Comment
N/A
N/A
Explained later
Hardware Controlled
Not Used
Explained later
Explained later
17
-
Hardware Controlled
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Troubleshooting
