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Maintenance Manual for Tablet MR07(TVE910S_V1.3)
This manual describes common failures and troubleshooting from the angle of circuit
principles. It is for your information. This manual introduces in general positions for circuit
investigation. Please refer to maintenance schematic diagram for circuit details.
I. Booting Failure
The phenomena of booting failure include no display of LCD (and no backlight), no
speaker sounds, no response of touch screen when touching, no response of power-on/
power-off key stroke and no response of reset. Reasons for these vary. Following the
troubleshooting steps below for failures of different kinds.
1. Abnormal System Power Supply
Firstly perform tests of short circuit to earth on the power test points on the board to
eliminate cause of short circuit to earth. Connect the board to DC power or battery,
power on the device and investigate the problem as stated in the table below.
Power Test Point Normal Voltage
DC 5V
VSYS
T27/VDD_LOG
T30/VDD_ARM
T28/VCC_DDR
T29/VCC_IO
Since RK platform apply PMU, power supply abnormity is usually caused by poor
welding of PMU and related peripheral components
2. Poor Welding or Abnormity of CPU, Memory and Flash
After the above investigation, the system power supply should be normalized. The
following circuits need to be checked.
a.
Check if the CPU and peripheral components are well welded.
b.
Check if Y2 crystal oscillates.
Table 1 System Power Supply
Reasons for Failures (Investigation Range)
Range
5+/-0.5V
Plug with DC power, this point shall have
5+/-0.5V
3.5V-5V
This point is system main power, if abnormity,
check if PMU well welded or if short circuit to
earth.
1.2V+/-0.2V
This is
check if PMU well welded or if short circuit to
earth.
1.2V+/-0.2V
This is CPU core power supply, if abnormity,
check if PMU well welded or if short circuit to
earth.
1.56V+/-0.1V
This is power supply of CPU and memory, if
abnormity, check circuit of PMU part.
3.0V +/-0.1V
This is IO power supply, check circuit of PMU
part.
CPU core power supply,if abnormity,
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