TELEREADER CWR-685E - 8 Description of Former MODEM Board

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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.
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-10
VR-11
VR-2
VR-3
VR-1
VR-6
VR-5
VR-4
VR-7
VR-8
2550 Hz
2975 Hz
2295 Hz
1700 Hz
2125 Hz
1445 Hz
2125 Hz
1275 Hz
Modulator (AFSK)
In the modulation system using timer IC, two sets of AFSK are changed over for each tone.