
3-12
ONE POINT REPAIR GUIDE
NO BOOTING IN CD/USB FUNCTION
After you turn on power key and displayed message in the following order (HELLO
VOL XX
CD or USB) on VFD, it will not display other message on VFD, and it will not boot-up normally.
8-4. SDRAM (IC502)
8-4-1. Solution
Please check and replace IC502 on MAIN board.
8-4-2. How to troubleshoot (Countermeasure)
1) Check below waveform & soldering status of SDRAM (IC502) on MAIN board.
If pin17(#CAS), pin18(#RAS), pin19(#CS), pin38(CLK), pin29(address), pin2(DQ) doesn’t come out,
check damping resistor (R568, R570, R544, R547).
2) If resistor is OK, then replace IC502(SDRAM).
3) After change IC502, if It is still not below waveform, Check IC501 (DSP IC).
8-4-3. Service hint (Any picture / Remark)
V
V CC
Re set
a ddress
da ta
// CS
R AS
/ W E
C AS
< Signal waveform >
< MAIN board bottom view >
IC502
IC502
Содержание OM7550
Страница 13: ...1 12 ...
Страница 16: ...2 3 Figure 3 Step 3 Seperate Cover_Side to out direction ...
Страница 17: ...2 4 ...
Страница 21: ...2 10 ...
Страница 58: ...3 37 3 SERVO IC401 X XI XO Fig 3 2 CD 16M IC401 pin31 Fig 3 1 Crystal 16 9344 MHz X400 11 10 12 10 11 12 ...
Страница 79: ...3 75 3 76 3 MAIN VFD RMC1 P C BOARD TOP VIEW ...
Страница 80: ...3 77 3 78 4 MAIN VFD RMC1 P C BOARD BOTTOM VIEW ...
Страница 81: ...3 79 3 80 5 FRONT P C BOARD TOP VIEW 6 FRONT P C BOARD BOTTOM VIEW ...
Страница 82: ...3 81 3 82 7 TOP VOLUME_FR1 P C BOARD TOP VIEW ...
Страница 83: ...3 83 3 84 8 TOP VOLUME_FR1 P C BOARD BOTTOM VIEW ...