Toshiba GD-1260, GD-1250 Dial pulse generation circuit, Line 1 Dial Pulse Generation Signal Q53

4.2.3Dial pulse generation circuit

NA/TW models

		NCU board
				C5	R4
				+12V	RLY2
				CML relay
				1		12			Q51	3
		4	Lb	9	1	8
					0	10			AG
Line	CN10						~
		3	La	4	1		DB1
					0	3	-	+
										CN9
									+5V
							~	4	1
									PC1
		3	a2					3	2
External	CN11									4
									Q53
telephone		4	b2
									SG
							Ring signal
							detection
							circuit
								Fig. 4-7

FAX board

3 CML1 21

CN501		IC29
		[IC26]
		ASIC
4	LD1	20

4

The dial pulse generation circuit consists of the diode bridge (DB1), photocoupler (PC1), the ASIC (IC29 [IC26]) on the FAX board and the other peripheral devices. It generates the dial pulses in the FAX transmission and dialing to the outside.

The ASIC makes the CML1 signal become HIGH to connect the line to the MODEM side. To generate the dial pulse, the ASIC makes the LD1 signal become HIGH to turn ON Q53. This allows the photo- coupler to come on and the current flows through the DB1 to send the dial pulses to the line.

Signal Name	Type	Active	Description	Destination
LD1	O	H	Line 1 Dial Pulse Generation Signal	Q53

*Values in [ ] are for GD-1250/1270 in case that the descriptions vary between GD-1210 and GD- 1250/1270.

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