Furuno CN-24 Service Manual
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Furuno CN-24 Service Manual

Furuno CN-24 Service Manual

Color net recorder
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COLOR NET RECORDER
CN-24

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Summary of Contents for Furuno CN-24

  • Page 1 COLOR NET RECORDER CN-24...
  • Page 2 Y o u r L o c a l A g e n t / D e a l e r 9 - 5 2 , A s h i h a r a - c h o , N i s h i n o m i y a , J a p a n T e l e p h o n e : 0 7 9 8 - 6 5 - 2 1 1 1 T e l e f a x :...

  • Page 3: Table Of Contents

    CONTENTS 1. GENERAL ......................1-1 1.1 POWER SUPPLY ..................1-1 1.2 UPWARD AND DOWNWARD SOUNDING ..........1-1 1.2.1 Sounding Rate ................1-1 1.3 DATA FORMAT FROM TRANSMITTER UNIT .......... 1-2 1.3.1 SYNC Code ..................1-3 1.3.2 Temperature Data ................1-3 1.3.3 Upward/Downward Sounding ............
  • Page 4 7. CALIBRATION OF PRESSURE SENSOR ............8. DISASSEMBLING/ASSEMBLING TRANSMITTER UNIT ......... SPECIFICATIONS....................SPC-1 EXPLODED VIEW....................MECHANICAL PARTS LIST..................................ELECTRICAL PARTS LIST SCHEMATIC DIAGRAM..................

  • Page 5: General

    1. GENERAL This chapter describes the basic operations of the transmitter unit. Most of operations are CPU controlled. 1.1 POWER SUPPLY The transmitter unit is automatically powered by the pressure switch when it descends 10 m in the sea and turned off when it ascends to 5m deep point. 1.2 UPWARD AND DOWNWARD SOUNDING The transmitter unit incorporates only one sounding transmitter/receiver circuit.

  • Page 6: Data Format From Transmitter Unit

    The receiver receives signals within the range in use at the first sounding, and it receives signals between 0 and 20 meters at the second and third soundings in both upward and downward directions. Generally, the blind zone occurs in short range due to the beam shape and rare transmission rate.

  • Page 7: Sync Code

    1.3.1 SYNC Code The synchronous signal consists of 32bits binary coded data. The DN SYNC code is attached to the beginning of each transmission cycle to enable the display unit identifying the signal. The coded pulses enable to reduce the effect of noise along the transmission line to the paravane receiver.

  • Page 8: Upward/Downward Sounding

    Note: In actual processing, the temperature data expressed by 9 bit binary number is divided into two parts, the lower 5 bits and the upper 4 bits, and the temperature data region is also divided into two sections. The time interval from the left edge of each section to temperature signal indicate the value of the lower 5 bit or upper 4 bit number.

  • Page 10: Circuit Description

    2. CIRCUIT DESCRIPTION 2.1 TRANSMITTER UNIT 2.1.1 Board Function Refer to the block diagram shown in figure 2.1. The transmitter unit consists of five PC boards. The table below shows the major functions of each PC board. Board Major Functions TRS.
  • Page 12 2V/DIV 100V/DIV 0.5ms/DIV 0.2ms/DIV Measuring point: TP6 on TRS.A board Measuring point: P4 #1 - P4 #4 Frequency:75 kHz Frequency:75 kHz Fig. 2.2 TX waveform Fig.2.3 TX trigger: TSMT Receiver Circuit The received signal from the transducer is first amplified by the RF amplifier and then mixed with the local oscillator output to get a 455 kHz IF signal.
  • Page 13 500mV/DIV 2V/DIV 2ms/DIV 100ms/DIV 2V/DIV 2ms/DIV Measuring point Measuring point: TP5 (VG) CH1: TP5 (VG) Sounding rate: High CH2: TP6 Fig. 2.6 waveforms of TVG voltage Fig. 2.7 TVG curve The STC (Sensitivity Time Control) curve is also generated in the TVG circuit. It suppresses the echoes just below the oscillation line, making the oscillation line thin so as not to cover the fish echoes close to the head rope.

  • Page 14: Depth/Temperature Measurement (Sen Board)

    2.1.4 Depth/Temperature Measurement (SEN Board) Depth Measurement Refer to the simplified depth measurement circuit shown in figure 2.8. Fig. 2.8 Simplified Depth Measurement Circuit 1) The pressure sensor for depth measurement constitutes a Wheatstone Bridge. It balances at 0 m and the voltage difference between "+" and " - " becomes zero. (In fact there is 0.6 mV approximately, so R10 adjusts the off-set voltage to obtain 0 V.) 2) When the sensor (S1 and S2) detects water pressure, the resistance of one sensor increases and that of the other decreases, developing a voltage proportional to the...
  • Page 15 Fig. 2.9 Conversion Curve; depth vs. voltage IMPORTANT The pressure sensor is a non-linear device and the characteristic varies from device to device. As the calibration data for the sensor in use are stored in the EEROM (U5 on SEN board), the sensor and SEN board should be used as a pair, that is, both the sensor and SEN board should be replaced if either of them is defective.

  • Page 16: Signal Transmission (Cont-A, Cont-B Boards)

    Fig. 2.11 Temperature Data (TP8) 2.1.5 Signal Transmission (CONT-A, CONT-B Boards) Refer to the block diagram on page 2-2. • Echo, Depth and Temperature Data Reading by CPU The eight bit echo data (256 step slices) from the TRS. A board are once applied to the dual-port RAM and finally transferred to the CPU.
  • Page 17 The low level signal Transmission can be improved against the noise. *16 bits = 15 bits for signal + 1 bit for frequency calibration data Fig. 2.12 Depth and temperature data from the SEN board are read by the CPU through the AD converter on the CONT B board and then stored in the scratch pad RAM U2.
  • Page 18 The echo data from the CPU consists of 8 bits (4 bits for echo data and 4 bits for frequency calibration data). The CPU determines the calibration value from timer's output count and writes it on the designated frequency calibration data bits to obtain 50kHz (33kHz, 40kHz) in no-modulation (no signal) state and 51kHz (34kHz, 41kHz) in maximum modulation state at TP1 and TP2.

  • Page 19: Display Unit

    The power supply circuit is made up of a PWM (Pulse Width Modulation). Inverter employing switching regulator techniques like other Furuno-made echo sounders and radars. The PWM inverter universally operates on ship's mains of 10 - 40 VDC. Against the vibration of the load condition, it regulates the DC output line by changing the width of its output pulse.
  • Page 20 2-11...

  • Page 21: Receiver Board (Amp 01P5725)

    RAM via the gate array. It also acquires ship's speed data by communicating with external navigational equipment in the Furuno CIF format and generates the clock signal for the SUB MCU (SYNC code detector). The video RAM has three picture pages and one scale/character page.
  • Page 22 1 Down SYNC code detection command 2 Detection report 3 Temperature data acquisition command 4 Acquisition report 5 Down sounding data acquisition command 6 Acquisition report 7 Depth data(MSB) acquisition command 8 Acquisition report 9 Up SYNC code detection command 10 Detection report 11 Catch monitor data acquisition command 12 Acquisition report...

  • Page 23: Check And Adjustment

    3. CHECK AND ADJUSTMENT 3.1 DISPLAY UNIT CHECK As the CN-24 color net recorder is properly adjusted at the factory, no adjustment is required in the field. This also applies to the PC boards supplied as maintenance parts. Do the following adjustments when malfunctioning is found or the equipment is overhauled.

  • Page 24: Power Supply Circuit (Pow Board 01P5737)

    3.1.2 Power Supply Circuit (POW Board 01P5737) Line Voltage Check Voltage Rated Value Measuring Point 01P5726, DISP 01P5737 4.85 to 5.15 V J12 #5 +12V 11.65t to 12.35 V J12 #1 -12V -12.6 to -11.4 V J12 #4 +15 V -15 V +130V (TV) TP7 and TP8...

  • Page 25: Testing In Air Without Paravane Receiver

    NOTE: 1) Stop the transmission within 5 minutes to prevent damage of transducer 2)The unit of 10 W TX output can not be checked in air The test can be done by one of two ways. • Reduce the output power down to 2.4Wand follow the procedures on page 4-4. •...

  • Page 26: Adjusting Transmitter Unit

    3.3 ADJUSTING TRANSMITTER UNIT 3.3.1 Gain Adjustment The transmitter unit incorporates the preset potentiometers shown in the table. All potentiometers except for R17 (gain adjustment) on the TRS. A board are for factory adjustment. For R17, though it has been properly adjusted, readjust it when clear picture is not obtained.

  • Page 27: Adjusting Transmission Frequency On Cont.b Board

    3. Operate the transceiver unit in air 4. Adjust the R10 on the SEN board as follows; 1) When depth indication is "0m", turn the R10 on the SEN board to CW slowly so that the depth indication becomes 1m. Then turn the R10 slowly to CCW by a point where the depth indication starts to change from 1m to 0m.
  • Page 28 8. Connect a probe CH1 of the oscilloscope to TP2 on the CONT.A board and the CH2 to the signal output of the signal generator. 9. Set the output frequency of the signal generator as shown bellow; Transmission frequency Signal generator 50 kHz 50 kHz 40 kHz...

  • Page 29: Adjustment Of Display Unit

    Transmission frequency Signal generator 50 kHz 51 kHz 40 kHz 41 kHz 33 kHz 34 kHz 18. Adjust the R5 so that the "Lissajous figure" obtained on the oscilloscope becomes stable, as shown in figure 3.3. 19. Set the DIP switch S2 #4 to ON. 20.

  • Page 30: Disp Board (01P5726)

    3.4.2 DISP Board (01P5726) Set the BRILLIANCE control at max. position, and the DEEP BLUE background is clearly distinguished from the blank area surrounding it. Set R64 (H-POSITION) so that the upper and lower blank areas become equal in width. Set R65 (BLUE) to the center position.

  • Page 31: Change Of Specifications

    4. CHANGE OF SPECIFICATIONS 4.1 DISPLAY UNIT 4.1.1 Range Unit, Sounding Range, Data Format, etc. Procedures 1) Turn off the power by pressing the PWR and OFF keys simultaneously. 2) Remove the display cover by loosening the fixing screws. 3) Change the settings of DIP switches S1, S2 and S3 on the DISP board 01P5726 referring to the figure/table below.
  • Page 32 * 1. This setting enables/disables the gain/clutter controls when playing back picture from picture recorder MT-12. "ON": Gain/clutter controls are disabled. The recorded picture is played back as it is. "OFF": Gain/clutter controls are enabled. The recorded picture can be gain/clutter controlled.

  • Page 33: Transmitter Unit

    4.2 TRANSMITTER UNIT 4.2.1 Sounding Range The sounding range is set with DIP switch S1 on the CONT-B 01P5741 board. The switch is factory-set to 80m for both the upward and downward ranges. To change the factory setting, refer to the figure below. Fig.

  • Page 34: Sounding Rate

    4.2.2 Sounding Rate The sounding rate is set with S2 (#1) DIP switch on the CONT-B 01P5741 board. The switch is factory-set to "HIGH" (190 times/min). When "LOW" is selected, the rate is down to 1/3 approximately. See table below. The relation between sounding rates and Upward/Downward ranges is shown below.

  • Page 35: Adjustment Mode

    4.2.4 Adjustment Mode The DIP switches S1 and S2 are used when depth and transmission frequency adjustments are required. The adjustment mode starts automatically when the DIP switch S2 #4 is set to OFF. Following table shows the function of each settings of the S1 and S2. 0: OFF, 1: ON Functions Adjusts offset (0 m) of depth scale...

  • Page 36: Parts Location

    5. PARTS LOCATION 5.1 DISPLAY UNIT I/F Board MIF Board 01P5750 06P0136 DISP Board 01P5726 AMP Board 01P5725 (under case) Fig. 5.1 Display Unit side view PNL Board 01P5729 Fig. 5.2 Display Unit rear side view...
  • Page 37 POW Board 01P5737 Degauss Board CE-DEGAU Deflection Board CE-MAIN Video Board CE-VIDEO Fig.5.3 Display Unit; top view...
  • Page 38 DISP Board (01P5726) CR13: SYNC CR12: HALT TP11 Jxx3 Jxx1 Jxx2 R48: ES SIG R64: H-POS R65: BLUE R66: RED TP10 TP12 Fig. 5.4 DISP board Adjusters Names Functions ES SIG Adjusts signal output voltage for external unit H-POS Adjusts vertical position of display, see chapter 3 BLUE Adjusts blue signal voltage, see chapter 3 Adjusts red signal voltage, see chapter 3...
  • Page 39 Test Points Remarks Signal input from AMP board AM OUT Signal output from AM detector circuit COP . SYNC. Composite synchronous signal for monitor circuit BLUE Signal output "Blue" GREEN Signal output "Green" Signal output "Red" TP10 TP11 Input of digital filter "U19" TP12 100K Dip-Switches...
  • Page 40 Test Points Names Functions Signal output of AMP circuit, maximum voltage;11 Vpp and 9 to 10 kHz Local 464.5 kHz Local 505.5 kHz for 50 kHz, 488.5 kHz for 33 kHz, 495.5 kHz for 40 kHz Analogue GND IF output Jumpers Remarks Jxx1...

  • Page 41: Transmitter Unit (Cn-2220)

    5.2 TRANSMITTER UNIT (CN-2220) Upward Transducer Link Transducer Pressure Switch Downward Transducer Pressure Sensor Test Switch (Screw) Temperature Sensor Serial Number of pressure sensor Gain Adjuster PC board Assembly Fig 5.7 Transmitter Unit...
  • Page 42 CONT. B CONT. A 01P5741 01P5740 TXSD.B 01P5739 SEN Board TRS B 01P5744 01P5743 TRS A 01P5742 Fig 5.8 Transmitter unit; PC board assembly...
  • Page 43 SEN Board (01P5744) U5: NVRAM Fig.5.9 SEN Board (01P5744) Test points Names Remarks Catch sensor signal TEMP Temperature signal output; 1 to 9 voltages. DEP1 Amplified output voltage of pressure sensor DEP2 Magnified voltage of DEP1; 1 to 9 voltages. Adjusters Names Remarkes...
  • Page 44 Test points Names Remarks ESIG Echo signal (DC) inputted to A/D converter SIG (AC) Echo signal (AC) TVG voltage TSMT Transmission trigger pulse CARRIER Carrier signal for mixer circuit; 530 kHz for 75 kHz, 630 kHz for 175 kHz Adjusters Names Remarks GAIN...
  • Page 45 CONT A (01P5740) Jxx3 Jxx1 Jxx2 Fig 5.12 CONT. A board (01P5740) Test Points Names Remarks Signal transmission output + Signal transmission output - (GND) Jumpers Remarks Jxx1 Sets output voltage 2.4 W 10 W Jxx2 Jxx1 A - LA A - HB Jxx2 B - LA...
  • Page 46 CONT B (01P5741) Fig 5.13 CONT. B board (01P5741) Dip-switches Remarks See chapter 4 Adjusters Names Remarks Gain See chapter 3 Off-set Test points Names Remarks Output of VCO circuit; 8 times the signal transmission frequency VFIN Output of D/A converter; clock signal TXSD B (01P5739) Jumper;...

  • Page 47: Board Interchangeability

    6. BOARD INTERCHANGEABILITY 6.1 DISPLAY UNIT All boards except the AMP board 01P5725 in the display unit are common PC board for all frequency units. The AMP board 01P5725 is fitted with a crystal oscillator for the designated signal transmission frequency (33, 40 or 50kHz) only. The frequency can be changed by adding a crystal oscillator and changing jumper settings.

  • Page 48: Transmitter Unit

    The TRS. A and TRS. B boards differ with the sounding frequency, i.e., 75 kHz or 175 kHz. 5. TXSD. B board 01P5739 The TXSD. B board can be used for all three signal transmission frequencies. Note: a jumper setting on the PC board must be put for the CN-24. See page 5-11 and circuit diagram.

  • Page 49: Calibration Of Pressure Sensor

    7. CALIBRATION OF PRESSURE SENSOR The calibration of the pressure sensor is required when either the pressure censor or the SEN board is replaced. Caution 1) The pressure sensor and SEN board should be replaced as a pair when either of them is defective, because of the calibration data for each sensor is stored in the NVRAM (U5 on the SEN board).
  • Page 50 4) Connect LED indicator to J13 on the TRS.A board as follows. TRS. A 01P5742 2.7 k Figure 7.1 LED indicator circuit 5) Connect receiving transducer or test cable to the display unit and the TX transducer, see pages 5-2/5-3, in order to obtain the depth data on the display. 6) Connect the oil pressure device to pressure sensor of the transceiver unit.
  • Page 51 2. Sensor curve adjustment Set DIP switches S1 and S2 as follow( S2 #4: OFF) #4 #5 #6 #7 off OFF "Temporal storing the "0" data of 1/5 curve" 1) Set the oil pressurize device to 0 kgf/ cm 2) Set DIP switches S1 and S2 as follow (S1 #2: ON) #5 #6 #2 #3 3) Confirm that the LED lights up from blinking.
  • Page 52 9) Set the oil pressurize device to 82.4 kgf/ cm , and keep it by the step 13. 10) Set DIP switches S1 and S2 as follow S2 #1 11) Confirm that the LED lights up from blinking. "Temporal storing the "0" data of 3/5 curve" 12) Confirm that the pressure is 82.4 kgf/ cm 13) Set the DIP switches S1 and S2 as follow;...
  • Page 53 17) Confirm that the voltage at TP4 changes from 9 to 1 volts "Temporal storing the full scale data of 4/5 curve" 18) Set the oil pressur to 164 8 kgf/ cm , and keep it by a step 22. 19) Set DIP switches S1 and S2 as follow 20) Confirm that the LED lights up from blinking.
  • Page 54 27) Confirm that the LED lights up from blinking. Caution The calibration data stored into NVRAM at a moment when the DIP switches are set to above. If the DIP switches are set to above before completing the adjustment. Improper calibration data are stored into NVRAM, which produce erratic depth indication. 28) Turn off the transmitter unit by rotating the screw of pressure switch to CCW..

  • Page 55: Disassembling/Assembling Transmitter Unit

    8. DISASSEMBLING/ASSEMBLING TRANSMITTER UNIT 1. How to fix or remove the Battery case and End Cover. Fig.8.1 Battery case and End cover...
  • Page 56 2. How to fix and remove the PC board assembly. Fig. 8.2 PC board assembly 3. How to fix and remove the Link Transducer Fig.8.3 Link Transducer...
  • Page 57 4. How to fix and remove the guide plate and wires from the plug P1. Fig.8.4 Guide plate and Plug P1...
  • Page 58 5. How to fix and remove the transducer. Fig. 8.5 Upward and downward transducers When removing the transducer from housing , follow to the procedure shown in figure 8.6. Prepare the tool shown in figure 8.6 and carefully rotate little by little. Too much rotating may twist off the wire connected to the transducer.
  • Page 59 Caution: do not pry the transducer with driver. Fig. 8.6 Removing transducer 7. How to fix and remove the Pressure Switch. Fig. 8.7 Pressure Switch...
  • Page 60 8. How to fix and remove the Pressure Sensor and temperature Sensor. Fig. 8.9 Pressure Sensor and Temperature Sensor...
  • Page 61 SPECIFICATIONS OF COLOR NET RECORDER CN-24 DISPLAY UNIT CN-2410 1. Display 14" diagonal, rectangular CRT. Echo ; presented in 7 color graduations (with selectable background color) Temperature ; presented in graphical form and digital value. 2. Presentation Mode (1) Downward mode...
  • Page 62 7. Temperature Indication Digital Readout; -50C - +400C in O.10C step, (200F - 1000F in O.20F step) Graph ; plotted in the interval of +50C(+100F). When the temperature rises above or falls below the limits of the scale, the graph is shifted to the center of the scale.
  • Page 63 3. Maximum Pressure 5kg/cm (equivalent to 50m) 4. Cable length & Strength 70m, tensile strength: more than 1000 kgf 5. Towing Speed Normal reception up to 6 knots TRANSMITTER UNIT CN-2220 1. Signal Transmission Characteristics and Operating Hour of Battery Pack Frequency Output Beam width Battery Operating hour TX Range* 33 kHz...

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