2.3.4.3. Digital Board Section
One of most difficult problems to deal with is when the system will not boot up.
The symptom: No response when the power is turned on. (No LCD display, keys are not accepted.)
Then first thing to do is check the power source, If there is no problem with the power supply unit, then there is a problem with the
digital unit (main board).
As there are many potential causes in this case (ASIC, etc.), it may be difficult to specify what you should check first. If a mistake
is made in the order of checks, a normal part may be determined faulty, wasting both time and money.
Although the tendency is to regard the problem as a serious one (IC malfunction, etc.), usually most cases are caused by solder
faults (poor contact due to a tunnel in the solder, signal short circuit due to solder waste).
Note:
1. Electrical continuity may have existed at the factory check, but a faulty contact occurred as a result of vibration, etc., during
transport.
2. Solder waste remaining on the board may get caught under the IC during transport, causing a short circuit.
Before we begin mass production, several hundred trial units are produced at the plant, various tests are applied and any
malfunctions are analyzed. (In past experiences, digital IC (especially SRAM and ROM) malfunctions are extremely rare after
installation in the product.)
This may be repaired by replacing the IC, (ASIC etc.). However, the real cause may not have been an IC malfunction but a
soldering fault instead.
Soldering faults which are difficult to detect with the naked eye are common, particularly for an ASIC and RA (Resistor Array). But
if you have an oscilloscope, you can easily determine the problem site or IC malfunction by checking the main signal lines.
Even if you don´t have such a measuring instrument, by checking each main signal line and resoldering it, in many cases the
problem will be resolved.
An explanation of the main signals (for booting up the unit) is below.
What are the main signals for booting up the unit?
Please refer to the 2.3.4.3.1. Digital Block Diagram.
The ASIC (including the CPU) (IC1) controls all the other digital ICs. When the power is turned on, the ASIC (CPU) retrieves the
operation code stored in the ROM (IC2), then follows the instructions for controlling each IC. All ICs have some inner registers that
are assigned to a certain address.
It is the address bus by which the ASIC (CPU) designates the location inside each IC. And the data bus reads or writes the data
in order to transmit the instructions from the ASIC (CPU) to the ICs.
These signal lines are all controlled by voltages of 5V (H) or 0V (L).
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Содержание KX-FT25LA
Страница 8: ...1 10 CCITT No 1 TEST CHART 8 KX FT25LA ...
Страница 9: ...1 11 LOCATION OF CONTROLS 1 11 1 OVERVIEW 9 KX FT25LA ...
Страница 10: ...1 11 2 CONTROL PANEL 10 KX FT25LA ...
Страница 13: ...1 13 3 SETTING YOUR LOGO 13 KX FT25LA ...
Страница 16: ...1 14 2 1 MAINTENANCE LIST 1 14 2 2 MAINTENANCE CYCLE 16 KX FT25LA ...
Страница 21: ...2 2 1 Document Jam 21 KX FT25LA ...
Страница 23: ...2 3 3 Simple Check List 23 KX FT25LA ...
Страница 24: ...2 3 4 TROUBLESHOOTING ITEMS TABLE 24 KX FT25LA ...
Страница 25: ...2 3 4 1 ADF Auto Document Feed Section 1 No document feed 25 KX FT25LA ...
Страница 26: ...2 Document JAM 26 KX FT25LA ...
Страница 28: ...4 Skew 28 KX FT25LA ...
Страница 29: ...5 Image is distorted When printing 29 KX FT25LA ...
Страница 30: ...6 Black or white vertical lines appear 7 Skewed receiving image 30 KX FT25LA ...
Страница 32: ...32 KX FT25LA ...
Страница 34: ...2 3 4 2 1 Defective facsimile section 1 Transmit problem 34 KX FT25LA ...
Страница 35: ...2 Sometimes there is a transmit problem 35 KX FT25LA ...
Страница 37: ...4 The unit can copy but cannot transmit receive 37 KX FT25LA ...
Страница 41: ...7 How to output the Journal Report 41 KX FT25LA ...
Страница 43: ...Countermeasure 43 KX FT25LA ...
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Страница 48: ...48 KX FT25LA ...
Страница 49: ...49 KX FT25LA ...
Страница 50: ...50 KX FT25LA ...
Страница 52: ...1 Entering the remote programming mode and changing service codes 52 KX FT25LA ...
Страница 56: ...2 3 4 3 1 Digital Block Diagram 56 KX FT25LA ...
Страница 58: ...Normal Wave Patterns 58 KX FT25LA ...
Страница 60: ...60 KX FT25LA ...
Страница 62: ...62 KX FT25LA ...
Страница 63: ...NG Example 63 KX FT25LA ...
Страница 66: ...Note Inside the digital board Inside the operation board 66 KX FT25LA ...
Страница 67: ...2 3 4 4 2 Defective ITS Integrated Telephone System Section 67 KX FT25LA ...
Страница 69: ...Refer to 2 3 4 4 Analog Board Section 69 KX FT25LA ...
Страница 71: ...2 Troubleshooting Flow Chart 71 KX FT25LA ...
Страница 72: ...72 KX FT25LA ...
Страница 74: ...2 3 4 6 Operation Board Section 1 No key operation 2 No LCD indication 74 KX FT25LA ...
Страница 76: ...2 3 4 8 Read Section Refer to 6 4 4 SCANNING BLOCK 76 KX FT25LA ...
Страница 77: ...77 KX FT25LA ...
Страница 78: ...2 3 4 9 Thermal Head Section Refer to 6 4 3 THERMAL HEAD 78 KX FT25LA ...
Страница 86: ...2 5 TEST FUNCTIONS 86 KX FT25LA ...
Страница 89: ...4 DISASSEMBLY INSTRUCTIONS 89 KX FT25LA ...
Страница 90: ...90 KX FT25LA ...
Страница 91: ...91 KX FT25LA ...
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Страница 101: ...5 3 FLAT PACKAGE IC INSTALLATION PROCEDURE 5 4 BRIDGE MODIFICATION PROCEDURE 101 KX FT25LA ...
Страница 102: ...6 CIRCUIT OPERATIONS 6 1 CONNECTION DIAGRAM 102 KX FT25LA ...
Страница 104: ...6 2 1 General Block Diagram 104 KX FT25LA ...
Страница 105: ...6 3 CONTROL SECTION 6 3 1 BLOCK DIAGRAM 105 KX FT25LA ...
Страница 114: ...6 4 2 Block Diagram 114 KX FT25LA ...
Страница 116: ...116 KX FT25LA ...
Страница 121: ...6 4 6 3 2 Scanning 6 4 6 3 3 Printing Note See 6 5 SENSERS AND SWITCHES 121 KX FT25LA ...
Страница 122: ...6 4 6 3 4 Copying 122 KX FT25LA ...
Страница 131: ...b Redundancy Compression Process Coding Mode This unit uses one dimensional MH format 131 KX FT25LA ...
Страница 133: ...6 7 Analog Unit Block Diagram 133 KX FT25LA ...
Страница 137: ...6 10 2 Circuit Diagram 137 KX FT25LA ...
Страница 140: ...6 12 POWER SUPPLY BOARD SECTION 140 KX FT25LA ...
Страница 153: ...10 TERMINAL GUIDE OF THE IC S TRANSISTORS AND DIODES 153 KX FT25LA ...
Страница 154: ...11 FIXTURES AND TOOLS 154 KX FT25LA ...
Страница 155: ...12 CABINET MECHANICAL AND ELECTRICAL PARTS LOCATION 12 1 OPERATION PANEL SECTION 155 KX FT25LA ...
Страница 156: ...12 2 UPPER CABINET SECTION 156 KX FT25LA ...
Страница 157: ...12 3 LOWER CABINET P C B SECTION 157 KX FT25LA ...
Страница 159: ...12 5 ACTUAL SIZE OF SCREWS AND WASHER 159 KX FT25LA ...
Страница 160: ...13 ACCESSORIES AND PACKING MATERIALS 160 KX FT25LA ...