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Pioneer PDP-42A3HD Service Manual page 90

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1
Basic Inspection
Power Supply is O.K. but the DTT Does Not Wake Up
A
Preliminary Checkpoints
Check the System Clock (27MHz)and the RESET terminal of CPU.
Check the UART communication terminals between CPU and digital board (UART0).
Check the I2C between CPU and LGDT3303 or EEPROM.
Check the Flash Memory or DDR-SDRAM.
B
C
(Pin 45 and 46) of DDR-SDRAM
D
Check system reset of Pin1 on
E
Useful Tips
1. An Unstable 27 MHz clock may be due to defect of X-TAL or clock generator (U261). Replace the X-Tal or U261.
2. DDR-SDRAM have difference clock inputs which are positive and others are negative signal (Double Data Rate).
3. Vref and VTT are have Vcc/2 and check the power source whether defected.
4. When replacing parts, be cearful of static charges from the tip of the solder iron that can easily damage the parts.
Also, check for assembly condition, soldering condition, or for incorrect or reverse insertion of parts.
5. If the problems are caused by CPU, change CPU board and download Serial Number.
F
T16
90
1
2
Power Supply is O.K.
but the STB Does Not
Wake up
Waveform 2
Check the System
Clock 27MHz (Pin 15) of IC
MK2475-33G (U261)
OK
Ch:CLK, Ch2:CLK~
Check DDR-SDRAM Clock
(U5, U6, U7 and U8)
OK
Ch:3.3V, Ch2:Reset
U281
OK
Ch1:Reset, Ch2:CS/ Ch3:OE/
Check RESET, CS and OE
signals of Flash Memory
OK
Check for other defective
modes
2
3
NG
Waveform 3
NG
Check the Vref and VTT voltage
DDR-SDRAM or related parts
Waveform 4
NG
Check the soldering state of
Waveform 5
NG
PDP-42A3HD
3
4
Check X-Tal(Y261) and
related parts
and clock of
U281 or Replace U281
Check Flash Memory
(U40) or related parts
4
T16

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