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3-16
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.
4-3. SERIAL FLASH (IC503)
4-3-1. Solution
Please check and replace IC503 on MAIN board.
4-3-2. How to troubleshoot (Countermeasure)
1) If the crystal(X501) does oscillate, check serial flash(IC503) on MAIN board.
Check pin8(VCC), pin6(CLK), pin1(CS#), pin2(DO), pin5(DI) of below waveform.
2) If pin1, 2, 5, 6, 8 doesn’t come out, check damping resistor(R511, R513, R514, R515) of IC503.
If damping resistor of IC503 is OK, then replace IC503. (it need to download program)
3) After change IC503, if It is still not below waveform, check IC501(DSP IC).
4-3-3. Service hint (Any picture / Remark)
VCC
CLK
DO
CS#
< Signal check point >
< Signal waveform >
Summary of Contents for CM7420
Page 13: ...1 12 MEMO ...
Page 15: ...2 2 MEMO ...
Page 19: ...A60 4 SPEAKER SECTION FRONT SPEAKER CMS7520F ...
Page 82: ...3 79 3 80 PRINTED CIRCUIT BOARD DIAGRAMS 1 SMPS P C BOARD TOP VIEW ...
Page 84: ...3 83 3 84 2 MAIN P C BOARD TOP VIEW ...
Page 85: ...3 85 3 86 MAIN P C BOARD BOTTOM VIEW ...
Page 86: ...3 87 3 88 3 FRONT_VFD P C BOARD TOP VIEW BOTTOM VIEW ...
Page 87: ...3 89 3 90 4 FRONT_MIC PORTABLE P C BOARD TOP VIEW BOTTOM VIEW ...
Page 88: ...3 91 3 92 5 FRONT_VOLUME P C BOARD TOP VIEW ...
Page 89: ...3 93 3 94 FRONT_VOLUME P C BOARD BOTTOM VIEW ...