CAUSE
There are three common causes for the unit returning to the standby (power OFF) state. Follow the repair procedure to determine which one is the cause.
- A defect in the power supply causes a loss of power to one or more ICs, resulting in no communications. When there are no communications,
- Syscon shuts down the player.
- Similarly, if an IC in the unit shorts the power supply, there will also be no communications and the unit will shut OFF.
- Incomplete communications between an IC and Syscon is considered a defect and shutdown is the protection.
Repair Procedure
Either a short circuit or a communications
failure in an IC is what is causing the problem.
Short Circuit
- Check all the output voltages from the power supply. If all the voltages are present, go to “Communications Failure”.
- If any voltages are 0V, unplug the MB-85 board to see if you can isolate the short. The power supply will regulate unloaded.
- A short on the +12 volt line means either IC801 or IC802 is defective since they are the only ICs (on the MB85 board) that use +12V. Remove IC802 and if it is shorted, check the sled motor by applying a 3Vdc from an external power supply to see if it will run.
- A short on the 3.3 volt line means any one of a number of ICs on the MB-85 board is bad. 3.3 volts feeds each IC through a three connection inductive “FL” filter chip component. This is shown on the 3.3V Distribution Diagram. Not all the ICs listed are used in every DVD player. The FL filter can be removed by applying excessive solder to one end and bringing it around to unsolder the remaining connections. Lift the hot filter off with tweezers.
- Although any IC can short, the more commonly shorted IC is IC701, fed by B+ filter FL701
Communication Failure
There is an initial
communications between IC201, IC202 and IC205/6 at power ON. Once these three
ICs have talked, Syscon IC202 communicates with the remaining ICs on the serial and parallel bus.
Syscon uses chip select pulses to select an IC, communicate with it and repeats
this pattern with the next IC. Since the pattern is the same, we can use the
chip select signal to determine which IC is not communicating.
- Resolder IC205/6 and recheck the unit for operation.
- If the unit works when ON but doesn’t turn ON consistently when the power button is pressed, perform S/B 62R1 to insure reliable reset of three ICs on the MB board.
- IC202 sends chip select pulses to ICs on the MB-82/85 board in the order listed in the chart. If IC202 gets no acknowledgement from an IC, the next chip select pulse will not output and the unit will shut down. Therefore if a chip select pulse is missing at power ON, the IC before it on the chain is not acknowledging. Check each chip select source at DVD power ON with a scope and determine which signal is missing. Suspect the previous IC on the list. For example, if chip select XCS (*6) was missing, the A/V decoder IC401 may be defective. Replace IC401.
POWER ON IC CHECK SEQUENCE
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Chip select source
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Destination IC
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CS 1 - IC202/pin 10
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SRAM IC204 / HGA IC601
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CE IC202/pin 11
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Flash ROM IC205/6
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CS 3 IC202/pin 8
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AV Decoder IC401
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CS 4 IC202/pin 7
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HGA IC601
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CS 2 IC202/pin 9
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AV Decoder IC401
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XCS IC601/pin 111
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ARP2 IC303
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HCS - IC601/pin 118
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Servo IC701
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Sometimes when a chip select signal is missing,
the IC it points to is actually not defective. Usually a communications failure
between IC202 and the remaining ICs on the serial or parallel bus is within the
MB-82/85 board. This could be caused by lack of power to non-communicating IC
or it could just be defective.
Another possibility is that one of the programs
in that IC cannot finish because of a mechanical defect, so there is no
acknowledgement signal to complete the communications. For example, if IC701 is
sending a sled drive move signal but the IC fails to receive a sled home
indication after a fixed time (“time out”), IC701 will not acknowledge IC202.
Syscon IC202 will tell IC201 to shut down. In
this failure example sled driver IC802 is defective so the sled cannot move.
Since IC701 is the last chip in the chain, all the chip select signals are
present. If the unit shuts down with all the chip select pulses present, IC701
is not sending the final acknowledgment signal so the problem is at IC701 or
its slave ICs (IC801 or IC802). In this case, use the test mode to manually
drive the focus, tracking and sled, tilt motors.
- Inspect IC205/6 and check to see if this IC is one of the few units that needs to be upgraded in the service bulletin # 61 for a 0.5-second lip sync delay. This upgrade has no relation to the green to red power light symptom.
