Toshiba GD-1220, GD-1221 service manual RLY3, IC3, IC5

EU/AU/AS/C models

NCU board

Line current

detection

circuit

FAX board MAIN board

								Q4											3
				+12V	RLY3														6
					CML relay							IC5							7
				1		12		AG											8
							C7		R28			Analog switch
					1	5		T1			13	0
			R26
	4	Lb		4
					0	3
										R29	14	1
															IC6
Line							RLY4			C13		3		1	2
					1	8					15	2
	3	La		9	0	10													CN4
CN3							Relay		R31	R36	16	3
	2	a2				2	3		AG
External						+12V				C12		11 10			IC3	11
																10
telephone						4	1
									R32	R30				Analog
	5	b2
														switch
										C14		R11	1	1					1
													2	0		15
											IC6
											5	7	13	1				IC4
																14			2
														0			6	7
													12
											IC7	1
									Q9	4		2
							Ring signal
							detection		AG
							circuit
											Fig. 4-5

3		CML1	21
6		ATT3DB1	22	CN5
7		RLADJ11	29
8		RLADJ21	63
CN262
		28,29
1	TXOUT1 [25,26]
			IC12
			[IC2]
		32
2	RXIN1	[29] MODEM

CN5

21144

22142 IC23

29141

63140 ASIC

The line path switching control circuit consists of the CML relay (RLY3) and analog switch (IC3, IC5) on the NCU board, the ASIC (IC23) on the MAIN board, and the other peripheral devices. It changes the path for the FAX send/receive signals and connects it to each control circuit.

The CML relay is switched according to the CML1 signal output from the ASIC on the MAIN board. When the CML1 signal goes HIGH, Q4 comes on to turn ON the CML relay.

The analog switch (IC3) is switched according to the CML1 signal and ATT3DB1 signal. When the CML1 signal or ATT3DB1 signal goes HIGH, the analog switch is turned ON.

The analog switch (IC5) is switched according to the RLADJ11 and RLADJ12 signals.

The analog switch is switched according to the states of the RLADJ11 and RLADJ21 signals. Turning ON the CML relay and analog switch allow the MODEM to be connected to the line.

Signal Name	Type	Active		Description	Destination
CML1	O	H	Line 1	CML Relay Control Signal	RLY3, IC3
ATT3DB1	O	H	Line 1	Attenuator Control Signal	IC3
RLADJ11, 21	O	H	Line 1	Return Loss Adjustment Signal	IC5

*Values in [ ] are GD-1221 in case that the descriptions vary between GD-1220 and GD-1221.

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

4 - 5

08/08