Line current detection circuit, REVA1, REVB1 | Toshiba GD-1221

4.2.4Line current detection circuit

NA/TW models

NCU board

					R87
					1	8
						PC3
					2	7
				C7
					3	6
						PC3
	CN10	4	Lb	R86	4	5
Line				R86

19

CN9

20

SG

FAX board

	19	REVA1	66
CN262				CN5
	20	REVB1	33

	MAIN board
	66	160
	CN5	IC23
	CN5	ASIC
		ASIC
	33	161

Fig. 4-8

The line current detection circuit consists of the photocoupler (PC3), ASIC (IC23) on the MAIN board and the other peripheral devices. It detects a dial tone and the hook status of the external telephone from the current flowing through the line.

When a dial tone is input from the telephone line, current flows through the line and the photocoupler is repeatedly turned ON/OFF. This allows the REVA1 and REVB1 to be the pulse signals and input to the ASIC, then the dial tone is detected.

When the handset is lifted from the external telephone, current also flows through the line and the pho- tocoupler is turned ON/OFF, then the off-hook state is detected.

Signal Name	Type	Active		Description	Destination

REVA1	I	-	Line 1	Current Detection Signal	IC23

REVB1	I	-	Line 1	Reverse Current Detection Signal	IC23

GD-1220/1221	© 2006 - 2008 TOSHIBA TEC CORPORATION All rights reserved
ELECTRICAL CIRCUITS

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Toshiba GD-1221, GD-1220 service manual Line current detection circuit, REVA1, Line Current Detection Signal IC23, REVB1

Contents

GD-1220/1221 Page Transportation/Installation Important Service Parts for Safety Vorsicht Contents 2006 2008 Toshiba TEC Corporation All rights reserved FAX Options GD-1220 GD-1221 RemarksSTUDIO165/205 Available STUDIO167/207/237 System firmware version Specifications DBm to -8 dBm The setting can be changed by 1 dB Transmission systemEmbedded DBm to 0 dBm Level -55 dBm or lower cannot be detected Comp Dimension width x length Printing areaFolio Features Specifications and Outline of System 08/08 Accessory Qty Accessories and PartsFollowing accessories and parts come with the FAX unit Option Function Model Extends the FAX functions when the FAX unit is installedOptions ADF Radf System ListNA/EU/AU/TW Units and Components Symbol Name Function Layout of PC BoardsFAX PWA-F-NCU-631 LSU-RELATED Functions Recording paper size Effective recording area Size Horizontal x Vertical Effective recording area For MJD, AUD, ASD, SAD, TWD, and CND models Unit mm inch Inch Feed direction Mm 0.16 inch Effective recording areaSize Horizontal x Vertical Effective recording range 297 x 293 x A4-R 210 x 206 x A5-R 148 x 144 x 257 x 253 x Print mode Print algorithm Recording paper selection algorithm and print algorithmRecording paper selection algorithm Reception print flowchart Start Receive FAX Judgment parameter Discard printing Bit Discard parameter Vertical reduction print Similar reduction print RTI For MJD, AUD, ASD, SAD, TWD, CND models ScanningST-R Comp Scanning width Recording paper range A4-R For MJD, AUD, ASD, SAD, TWD, and CND modelsRecording paper range Recording paper range LT long Comp long LD long Comp *2 Comp *1Recording paper range A4 long B4 long A3 long Folio Folio *1 Error processing Limitations on reception print Order Drawer LSU-RELATED Functions Circuit Connection and Procedure to Change Mode Dial call-up transmission to a telephone circuitYES Standby state Selection of the communication mode Procedure to select the transmission modeCommunication mode Toshiba original procedure Telephone circuit Signaling System Diagram and Signal Forms Circuit control signalsThis signal can be sent manually Signal form Signal name Signal form Communication with the binary signals Image signalMode change is possible only for the original set manually Receiver Only error frame retransmitted 1 completed 2 completed Frames received Error occurred MCF CED NsfcsidisCFR Binary signals PIP PINPRI-EOM PRI-MPS Format When this frame is the last frame, X =FCF FIF FCS FCF format of each binary signal Binary signal Format TCF 9600 bps, 7200 bps4800 bps, 2400 bps 3 V.8/V.34 communication sequence Standard procedure Transmitter Receiver Line closed Signal name Abbreviation Function Remarks Tone signal between Hz and 3,750 Hz in units150 Hz Frequency transmission Capability TRN ALT Maintains the synchroniza 7E H Tion Receives an NSF sent fromTransmitter Receiver Image data Image data are sent. Transmitter Scrambled data frame to beIs completed Encoded image data Turn off Scrambled 1 is sent for Short training Signal PPS-EOPTransmission of one Is completed Informs to disconnect the line Line closed DIS cannot be recognized DIALING/COMMUNICATION Control DIALING/COMMUNICATION Control DIALING/COMMUNICATION Control DIALING/COMMUNICATION Control FAX Automatic Switching TEL modeFAX mode General functions DIALING/COMMUNICATION Control Configuration GD-1220/1221 Configuration Description of Circuits EU/AU/AS/C models Line path switching control circuit Signal Name Type Active Description DestinationCML1 ATT3DB1 IC5 RLY3, IC3IC3 Line 1 Dial Pulse Generation Signal Q53 Dial pulse generation circuit Line 1 Dial Pulse Generation Signal Line Current Detection Signal IC23 Line Reverse Current Detection Signal IC23Line current detection circuit REVA1 Line 1 Current Detection Signal IC23 Current Reverse Line 1 Current Detection IC23 Signal Line 1 CI Detect Signal IC23 CI detection circuit Line 1 CI Detection Signal IC23 Line monitor circuit FAX board Monitoring signal Ringer/AlarmLine Monitor LOW High Sound volume PC Boards PWA-F-FAX-635 GD-1220 PWA-F-FAX-678 GD-1221 PWA-F-NCU-631 NAD, TWD, SAD PWA-F-NCU-631 MJD, AUD, ASD, CND Electrical Circuits Installation Explanation to the Users Installation