Strong SRT8500 User manual

service manual
DTT1609

CONTENTS
3.2 COMPONENT LAYOUT OF MAIN BOARD
1.6 AUDIO
2.1 SCHEMATIC OF POWER SUPPLY
# ADDITIONAL TROUBLESOOTHING
3 SCHEMATIC.COMPONENT LAYOUT AND BOM OF MAIN BOARD
3.1 SCHEMATIC OF MAIN BOARD
3.3 BOM OF MAIN BOARD
1.1 SHORT TEST
1 MAIN BOARD TROUBLE SHOOTING GUIDE
1.2 POWER
1.3 MAIN CLOCK
1.4 CVBS
1.5 RGB
2.2 COMPONENT LAYOUT OF POWER SUPPLY
2 SCHEMATIC.COMPONENT LAYOUT AND BOM OF POWER SUPPLY

Main Board Trouble Shooting Guide
(DTT1609)
Here are the procedures you can refer to whenever terrestrial receivers do not
operate properly. You can check problems and repair the units on the basic level
according to the following procedures
Main Board
1
2
35
4
7
6
8
910

1. SHORT TEST
☞Before turning on AC power, check POSITIVE VOLTAGE and also check whether SHORT
between GROUND's and PIN SHORT for TUNER are detected or not.
2. Checking POWER.
☞ +12V(SCART),+5V(ANTENNA_POWER,IR,VIDEO BUFFER,HDMI,USB), +3.3V(TUNER, FLASH,
CPU),+2.5V(DEMOD),+1.5V(DDR3,CPU),+1.3V(CPU DEMOD)
1

1
+5V
+12V
+5V For HDMI
6
+3V3 For
Tuner

2
+3V3
For C
p
u
10
+3V3
+1V5
For C
p
u
+1V5 For
DDR3
3
+1V3 For
Cpu
2

10 +2V5 For
DEMOD
5
+1V3 For
DEMOD
+5V For
USB
8
+5V For Video
Buffer
+5V For Audio

3. Check MAIN CLOCK 24MHz and SYSTEM CLOCK (PLL) to operate normally after SYSTEM
operates.
☞For the first thing, check 24MHz from Y401 flows into [OSCI(PIN B18)] of MAIN
CPU
If the 24MHz is unstable, Check Y401 is damaged or not.
If you are firm belief of damage for the device, then replace the device.
☞ And then, check that 800MHz is being supplied to DDR3 with RESET
If the clock 800MHz on Pin-J7&K7 of U401 is not generated from inside of the
chip,Please check the soldering state of U401,U402 and U403
(MAIN CLOCK) 24MHz
(DDR3 CLOCK) 800MHz

DDR3 CLOCK 800Mhz
MAIN CLOCK

4. In case that MAIN CPU operates normally but there is no VIDEO display.
▶ In case of no OSD display.
☞ If OSD is not displayed, check first if VIDEO SIGNAL is detected from
[R419(CVBS),R416(R),R417(G),R418(B)] of MAIN CPU.
☞ And then, check any part with no DATA after checking VIDEO SIGNAL from VIDEO
SIGNAL PORT of MAIN CPU, or SCART
▶ In case of no MPEG display
☞ There can be a variety of reasons for the case
☞ Check first that CHANNEL of TP SIGNAL is locked properly.
☞ After this signal input to the resistor connected to MAIN CPU is done normally,
A/V DATA comes out from MAIN CPU and flows into MPEG CHIP(MAIN CPU). If there is no
problem to here, it is thought that MAIN CPU and channel are operating without any
fault.
☞ In case of no MPEG display to this point, inspect any disorder by checking
U701(TUNER IC) and I/F of MAIN CPU.