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TELEREADER CWR-685E, Service Manual

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TELEREADER CWR-685E Service Manual Download Page 23

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. This output of baud rate clock can be checked on the TP-10.

The relation between baud rate and clock frequency is as follows:

Clock frequency = Baud rate × 16

Positions of adjusting VRs and test points on PCB:

Summary of Contents for CWR-685E

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

Page 2: ...ng display 14 C Abnormal external display 15 4 2 Trouble of CRTC block 16 4 3 Trouble of computer block 19 4 4 Trouble in CW transmission 20 4 5 Trouble in CW reception 20 4 6 Trouble RTTY 21 5 Descri...

Page 3: ...ram 38 2 Keyboard circuit diagram 39 3 Built in CRT unit circuit diagram 40 4 Main PCB circuit diagram 5 MODEM PCB circuit diagram 6 General wiring diagram 7 Mechanism assembly drawing 11 Attached boo...

Page 4: ...re place the two ICs at the same time If specified tool cannot be used when dismounting remo ve with particular care not to bend the lead pins of ICs 4 In the description H level at TTL level or merel...

Page 5: ...directional data For selection of address there is an address data output terminal of 16 bits but since the A15 of higher position is not used in this system the total address space is 32 kbytes For c...

Page 6: ...d the key operation signal is given to a key signal input J3 2 and is read from the key sig nal input port pin 4 of IC45 to light up the LED for CW monitor thereby opening the output gate of CW monito...

Page 7: ...rolling the system by means of other microcom puter or the like instead of the keyboard In such a case the parallel data should not be converted until the response of ACK signal is confirmed When the...

Page 8: ...ile it is being depressed the J7 2 terminal on main PCB is connected to GND FILTER In OFF position the J7 3 terminal on main PCB is connected to GND In ON position the J7 4 terminal on main PCB is con...

Page 9: ...ontrol signal output ports This paragraph describes the performance of output ports on the main PCB in which outputs vary depending on the setting of each switch or commands These outputs are controll...

Page 10: ...3 3 Actions of CW audio demodulator The IC42 is a Norton amplifier having four logic circuits of identical function contained in one pack age In this system two of the four logic circuits are used to...

Page 11: ...y the output frequency of clock generator composed of IC35 TR1 TR2 The SPEED slide VR on the front panel is connected to the J9 8 to J9 10 terminals on main PCB When the voltage at J9 9 terminal is hi...

Page 12: ...eshooting Troubleshooting flow charts 4 1 Trouble of built in display A No display The built in display of this System appears in about ten seconds after the power switch is turned on If no display ap...

Page 13: ...he first place check the crystal oscillator and dividing circuit Trouble in CRTC block Check the frequency of the following parts in the numerical order checking of crystal oscillator di viding circui...

Page 14: ...w 12 V the performance of built in display becomes unstable 2 In the case of power source containing ripples the average voltage should not be more than 14 5 V If the display screen still fluctuates t...

Page 15: ...signal of 1 0 0 2 Vpp at 75 ohm load The sync signal level is 30 and video signal level 70 H SYNC 15 644 kHz pulse width 5 32 s V SYNC 59 26 Hz pulse width 2 1 ms Non interlaced raster scan system Num...

Page 16: ...16 4 2 Trouble of the CRTC block Is horizontal sync signal of about 63 92 s period delivered to CP1 and is vertical sync signal of about 16 875 ms period to CP2...

Page 17: ...17...

Page 18: ...18...

Page 19: ...the level is set to L for about 20 ms and is then set to H again e With the CW RTTY selector at RTTY when the SEND AUTO RECEIVE selector is set at SEND the switch is turned on and pin 14 of IC40 becom...

Page 20: ...e see the actions of external control signal output ports par 3 2 4 5 Trouble in CW reception When reception of CW is in trouble check if signal appears at check points of TP 5 TP 2 TP 4 While referri...

Page 21: ...signals are passed through a limi ter 1 4 IC3 and converted to signals stable in vertical direction The signals can be checked on TP 2 Then necessary frequency should be selected by the programmable...

Page 22: ...ogrammable divider is divided again to 1 2 and converted to a neces sary frequency of 50 duty One of the converted outputs is passed through audio amplifiers TR3 TR4 to become a monitor sound output w...

Page 23: ...by this divider is divided again to 1 2 and converted to a necessary frequency of 50 duty to delivered This output of baud rate clock can be checked on the TP 10 The relation between baud rate and cl...

Page 24: ...24 5 4 MODEM printed circuit board block diagram...

Page 25: ...R E from keyboard and set in echo back mode 6 Transmit RYRYRY from keyboard In this operation a self diagnosis loop is made In normal state Regardless of the selected position of RX TAPE selector on t...

Page 26: ...26...

Page 27: ...27...

Page 28: ...28 6 2 Modulator AFSK...

Page 29: ...29 6 3 Baud rate clock unit...

Page 30: ...30 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 31: ...31...

Page 32: ...B Q W E R T Y U I O P CR A S RS FS BS DLE DCI ETB ENQ DC2 DC4 EM NAK HT SI DLE NUL ESC CR SOH DC3 CAN CAN Q W E R T Y U I O P CR A S 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 5...

Page 33: ...same as 811001 0 but since the IC numbers and VR numbers differ refer to the wiring diagram The correspondence of VR numbers is as follows 801230 0 811001 1 Frequency VR 4 VR 5 VR 6 VR 7 VR 8 VR 9 VR...

Page 34: ...icked 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 45 5 50 57 56 92...

Page 35: ...CMOS LS TTL LS TTL LS TTL LS TTL LS TTL LS TTL PCI ROM ROM CPU PIA LS TTL LS TTL TIM LS TTL LS TTL LS TTL LS TTL LS TTL LS TTL OP AMP CMOS PLL LS TTL LS TTL REG REG R SW R Hi Hi Hi Hi Hi To Hi Hi Hi...

Page 36: ...Part No IC1 IC2 IC3 IC4 IC5 IC6 IC7 IC8 IC9 IC10 IC11 IC12 IC13 IC14 IC15 IC16 IC17 IC18 IC19 IC20 IC21 TR1 TR2 TR3 TR4 D1 D4 D5 D6 D7 D8 D92 IC IC IC IC IC IC IC IC IC IC IC IC IC IC IC IC IC IC IC I...

Page 37: ...IC13 IC14 IC15 IC16 IC IC IC IC IC IC IC IC IC IC IC IC IC IC IC IC OP AMP OP AMP OP AMP CMOS OP AMP OP AMP TTL CMOS LS TTL LS TTL CMOS LS TTL M M M To M Hi To Hi Hi To LM339 or equivalent LM339 MC33...

Page 38: ...38 BLOCK DIAGRAM...

Page 39: ...39...

Page 40: ...40...

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