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TELEREADER CWR-685E Service Manual

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CWR-685E
SERVICE MANUAL
Digitization and editing of text and images by DC7XJ, August 2019

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Summary of Contents for TELEREADER CWR-685E

  • Page 1 CWR-685E SERVICE MANUAL Digitization and editing of text and images by DC7XJ, August 2019...

  • Page 2: Table Of Contents

    Table of Contents Page 1. Introduction (Concept and cautions of troubleshooting) 2. General description Composition Flow of signal Control of SW OUT REMOTE Flow of signal in transmission 3. Input/Output actions Actions of switches Actions of external control signal output ports Actions of CW audio demodulator Change of CW transmission speed 4.
  • Page 3 10. Attached drawings Block diagram Keyboard circuit diagram Built-in CRT unit circuit diagram Main PCB circuit diagram MODEM PCB circuit diagram General wiring diagram Mechanism assembly drawing 11. Attached book CWR-685E Operating Instructions...

  • Page 4: Introduction (Concept And Cautions Of Troubleshooting)

    1. Introduction (Concept and cautions of troubleshooting) 1) When repairing a trouble in a computer system, it is essential, in the first place, to distinguish whether the trouble is due to software or hardware. When it is found to be a hardware trouble, it is then required to judge whether it is due to inside of the interface device –...

  • Page 5: General Description

    2. General description 2.1 Composition The block diagram of this System is shown in attached drawing. The program ROM contains a total of 6 k bytes, consisting of 2732 × 1 and 2716 × 1; the RAM has 128 bytes built in the MPU and 2 k bytes of 2114 ×...

  • Page 6: Flow Of Signal

    2.2 Flow of signal A block diagram is shown in attached sheet. Referring to the block diagram, the flow of signal is explained below. An audio signal fed from the AF IN (RX or TAPE) terminal of the rear panel when receiving is selec- ted by the RX/TAPE input selector on the front panel, and is delivered to AF OUT terminal in the rear panel, and is, at the same time, fed into AF input (J3-1) on MODEM PCB and AF input (J9-1) on main PCB.

  • Page 7: Control Of Sw Out Remote

    2.3 Control of SW OUT REMOTE The SW OUT REMOTE terminal of the rear panel is connected to the REMOTE (J3-4) terminal of main PCB. This terminal is directly shorted by the contact of the SEND-AUTO-RECEIVE switch when this switch is set to SEND side. When AUTO or RECEIVE position is selected, this terminal is controlled by the TR9 on the main PCB.

  • Page 8: Input/Output Actions

    GAIN VR in the rear panel, and is synthesized with the signal of CW monitor OSC at 800 Hz which is delivered from J3-7 on main PCB (in actual operation, either one signal only is gi- ven here). After level adjustment at AFSK GAIN VR, the signal is fed again to J4-1 terminal on MODEM PCB, and reappears at J4-4 terminal as AFSK signal having shaped waveform, and is delivered from the AFSK OUT terminal in the rear panel.

  • Page 9: Actions Of External Control Signal Output Ports

    NOR/REV In REV position, J1-2 terminal on MODEM PCB is connected to GND. BAUD 6-position switch One of the terminals J2-2 to J2-7 on MODEM PCB is connected to GND. SHIFT 3-position switch When 425 is turned on, the J1-12 terminal on MODEM PCB is connected to GND. When 850 is turned on, the J1-11 terminal on MODEM PCB is connected to GND.

  • Page 10: Actions Of Cw Audio Demodulator

    Pin 5 During transmission of CWID, the level becomes H in synchronism with CW code. When the level is H, the SW OUT FSK is turned on, and the FSK TTL OUT is set to L level. In CW mo- de, this pin operates in synchronism with pin 2.

  • Page 11: Change Of Cw Transmission Speed

    The audio signal obtained from the band pass filter passes through the coupling capacitor C38, and is lowered in level by the 1/11 attenuator composed of R15 and R14, then is applied to input pin of PLL decoder IC through C20. The dividing ratio of R15 and R14 is so set that the PLL decoder IC (IC44) may be locked when the amplitude of TP-5 exceeds 70 % of the maximum value.

  • Page 12: Troubleshooting

    deo signal, which is picked up from the VIDEO OUT terminal in the rear panel. The resistor R8 is inserted so that the output may be 1.0 ±0.2 V when a load of 75 ohms is applied to the VIDEO OUT terminal.
  • Page 13 Set the VOLUME slide VR lever to the highest position. Set the CW/RTTY selector to RTTY side. After thus setting, is the AFSK monitor sound oscillated when SEND-AUTO-RECEIVE selector is set to SEND and does the oscillation stop shortly after the selector is returned to RECEIVE position? Probable causes are trouble of crystal oscillator Trouble in CRTC block or dividing circuit, failure of Computer or...

  • Page 14: (B) Fluctuating Display

    (B) Fluctuating display The power source requirements of this System are voltage of DC 12 to 14.5 V and current of not less than 1.65 A. Power source conditions 1. Stabilized power source is not necessarily required. The System can operate on a power source containing slight ripples.

  • Page 15: (C) Abnormal External Display

    (C) Abnormal external display Is built-in display normal? CRCT on COMPUTER BLOCK Are the VIDEO OUT terminal and external dis- play unit connected with 75-ohm coaxial cable correctly without any shorting or breaking? Connect correctly. Is the external display a home TV set? ┌───────────────────────┘...

  • Page 16: Trouble Of Crtc Block

    4.2 Trouble of the CRTC block Is horizontal sync signal of about 63.92 µs period delivered to CP1, and is vertical sync signal of about 16.875 ms period to CP2?

  • Page 19: Trouble Of Computer Block

    4.3 Trouble of Computer block Check whether the Computer block is operating normally or not in the following procedure. The output level of pins 2, 4, 5, 6, of IC37 should be always H level as far as the Computer is operating normally.

  • Page 20: Trouble In Cw Transmission

    4.4 Trouble in CW transmission CW transmission is synchronized with CW sending clock. The CW sending clock is made in IC35, and is fed from CW sending clock input port (pin 2 of IC40) into the Computer block. When this clock stops oscillation, CW cannot be transmitted. The oscillation waveform at TP-3 is fixed at L level within about 15 to 20 µs, while the duration of H level varies with the position of SPEED slide VR.

  • Page 21: Trouble Rtty

    4.6 Trouble of RTTY The speed of RTTY transmission and reception is selected by the BAUD six-position switch. Turn on only one of the buttons. If two or more buttons are turned on or all buttons are turned off, the system does not operate normally.

  • Page 22: Modulator

    5.2 Modulator (AFSK) On the basis of the 10 MHz crystal oscillator, necessary frequencies are divided by dividers and used. The dividing schedule from 10 MHz is as shown below. The dividing output of IC17, 18 is the total of dividing ratios in all lines where diodes are provided„ Example: Low mark: 1 + 4 + 16 + 32 + 64 + 128 = 245 Input frequency...
  • Page 23 The dividing output of IC14, 18, 21 is the total of dividing ratios in all lines. The output being divi- ded by this divider is divided again to 1/2 and converted to a necessary frequency of 50 % duty to delivered.

  • Page 24: Modem Printed Circuit Board Block Diagram

    5.4 MODEM printed circuit board block diagram...

  • Page 25: Troubleshooting Of Modem Printed Circuit Board

    6. Troubleshooting of MODEM printed circuit board 6.1 Demodulator Preparation (1) Set the MODEM selector on the back panel to INT side. (2) Connect AFSK OUT TX and AF OUT on back panel. (3) Set RX/TAPE selector on front panel to RX position. (4) Set the other switches on the front panel to be ready to send and receive in RTTY mode.

  • Page 28: Modulator

    6.2 Modulator (AFSK)

  • Page 29: Baud Rate Clock Unit

    6.3 Baud rate clock unit...

  • Page 30: Keyboard Troubleshooting (Kb-685E, Kb6850)

    7. Keyboard troubleshooting (KB-685E, KB-6850 7.1 Troubleshooting flow chart of keyboard (PCB No. 820226-1) Referring to the attached wiring diagram, check the keyboard in connected state.

  • Page 32: List Of Keyboard Output Codes

    7.2 List of keyboard output codes CTRL- CTRL- NORMAL SHIFT CTRL NORMAL SHIFT CTRL SHIFT SHIFT " & (BS) (ETB) (CAN) (ESC) (SUB) (DLE) < (<) > (>) (DEL) (HT) (VT) (FF) (SHO) (SP) (FS) (GS) (SI) (SO) (DEL) (ACK) (CR)

  • Page 33: Description Of Former Modem Board

    8. Description of former MODEM board In models from lot numbers 21xxxx to 23xxxx, the type of MODEM board differs. The board for re- pair is 811001-0 only, which can be replaced without modification. The demodulator is same as 811001-0, but since the IC numbers and VR numbers differ, refer to the wiring diagram.
  • Page 34 Baud rate clock The baud rate clock adjusts the voltage applied to pin 7 of timer IC, and necessary frequencies are picked up. For readjustment, adjust the VRs by connecting oscilloscope to the TP-12. The relation between the baud rate, frequency, and time is as follows: Baud rate Frequency (f) Hz Time (T) ms...

  • Page 35: Parts List

    9. Parts list Semiconductor Parts List (1) 1. Main PCB (No. 810529-1) Code No. Name Type Maker Part No. LS. TTL HD74LS00 or equivalent LS., TTL HD74LS74 " LS. TTL HD74LS74 " LS . TTL HD74LS163 " LS . TTL HD74LS04 "...
  • Page 36 D13-D14 IS15S3 " V06C " D16-D19 IS1588 " D20-D26 V06C " IS1588 " RD4.7A " RF.SW 2SA495 -50 V -150 mA RF.SW 2SA495 -50 V -150 mA 2SC1815 60 V 150 mA 2SC1815 60 V 150 mA 2SB649C -180 V -1.5 A 2SC1515 200 V 50 mA 2SC1515...
  • Page 37 3. Modem PCB (801230-0) Code No. Name Type Maker Part No. OP. AMP LM339 or equivalent OP. AMP LM339 " OP. AMP MC3301 " CMOS TC4051 " OP. AMP MC3301 " OP. AMP LM324 " HD14053 " HD7473 " HA17555 "...
  • Page 38 BLOCK DIAGRAM...

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