Contn:
LAMP DOOR SWITCH
The circuit operates by monitoring the door switch in the lamp assembly. If the lamp door is left open, a signal is sent to the system microprocessor (pin 49) on the POWERCTL line, invoking a shutdown. A signal is also sent to pin 19 of the system microprocessor (DOOR_OPEN) to identify this particular shutdown.
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Color wheel & DMD fan rotation
One circuit linked to the system microprocessor at
pin 49 monitors both the DMD fan and the Color wheel exhaust fans. In the event
fan rotation ceases, a signal is sent down the POWERCTL line to trigger unit
shutdown. As this is the same line used to trigger a lamp door open shutdown,
the microprocessor relies on the above mentioned DOOR_OPEN signal to pin 19 to
be the determining factor in identifying the type of shutdown.
The remaining shutdown circuits are indirectly
monitored by the system microprocessor by way of communication with the Backend
Process (BEP) microprocessor, shown in Figure 23. Another single chip microcomputer,
the 100-pin M30626FHPGP is up to the task of relaying real-time temperature
information to the system microprocessor for the purpose of protecting against
over-temperature situations.
Color Wheel and DMD Temperature
BEP microprocessor IC501 monitors color wheel and DMD
temperature at pins 1 (FANDAC2) and 2 (FANDAC1), sending that information to
the system microprocessor. IC601, in turn, uses the information to alter fan
speed to accommodate changes in temperature. Should the temperature rise to harmful
levels, the system microprocessor shuts the unit down to avoid damage.
BEP Microprocessor
The BEP
microprocessor also communicates with the DMD panel and the lamp ballast supply
to accomplish other tasks, as instructed through communication with the system
microprocessor. These tasks involve altering the operating parameters of the
lamp ballast supply and the DMD panel to coincide with user preferences
regarding lamp power usage and video display choices. EEPROM IC503, the same
type used by the system microprocessor, assists the BEP microprocessor in these
tasks by providing the same functions IC603 provides to IC601.
Two Way Communication
The BEP
microprocessor also communicates with the DMD panel and the lamp ballast supply
to accomplish other tasks, as instructed through communication with the system
microprocessor. These tasks involve altering the operating parameters of the
lamp ballast supply and the DMD panel to coincide with user preferences
regarding lamp power usage and video display choices. EEPROM IC503, the same
type used by the system microprocessor, assists the BEP microprocessor in these
tasks by providing the same functions IC603 provides to IC601.
SERVICE MODE CHECKS
This type of communication allows for adjustments,
updates, troubleshooting, and occasional repairs. While access to the system
microprocessor offers convenience in these areas, it must be noted that other parameters
of operation may inadvertently be changed if extreme caution is not used
whenever the feature is activated.
The upper level of data, stored in EEPROM IC603 and
used by the system microprocessor, can be accessed and manipulated, as
necessary, by entering unit service mode in the manner described in the unit
service manual. Alterations to data at
this level may be required during general service procedures and are typically
accomplished by remote control. While inadvertent changes in this area are not
generally life threatening to the unit, functionality and features may be negatively
influenced. The best practice when working with this level of data involves
recording address and data values prior to making adjustments to the stored
data. Changes to the stored data must be saved, as described in the unit
service manual, following any necessary alterations.
Service Mode Entry Method
- Press the "Mute" button twice on the customer remote control. Press "Mute" button again and Hold it while pressing the "Menu" button on the front panel of the TV set.
- A Service Mode indication will be given by the presence of an "S" displayed in the upper right of the screen.
- Press "Menu" button on the remote control, or "Menu" button on the front panel of the TV to enter the adjustment Menu.
- Use Ch UP / Ch Dn button to access the selected register requiring change. In the case DMD Bias the display will indicate "DMDB". Color Wheel Delay will use display "CWDL" and "CWDH".
- Use Vol Up / Vol Dn to adjust the value of the selected register.
- To "EXIT" service mode, press the Power button to turn Off the TV Note: With DLP product there is a normal delay for picture to return with a quick On and Off cycle.
Complete instructions regarding these issues
will be included with the Toshiba Service Interface Kit –P/N IICB
Flash Memory
The actual system microprocessor programming (mask)
can be re-written (updated) if the need arises. Figure shows Flash ROM IC609,
used for just such a purpose.
SOFTWARE REVISION FOR CLOCK TIME LOSS PROBLEM
If On-Screen Clock looses approximately 7 minutes every 24 hours, replace IC609 [EPROM] on the OPSS / Scaler Module using part number [23085328]. This device uses a plug in socket.
