Mitsubishi Electronics VS-60609 service manual Audio Circuit Purpose, Input Level, Service Mode

MODELS: VS-45609 / VS-50609 / VS-55609 / VS-60609 / VS-60719 / VS-70709

[Audio Circuit]		Purpose:		Set the input signal level to the MCS circuit.
1. Input Level		Symptom: Distorted sound during a stereo broadcast.
Measuring	Oscilloscope	1.	Supply an RF monaural signal to the Ant A input, 300 Hz at 100% modulation
Instrument
Test Point	TP14A, TP15A		(25 kHz deviation).
		2.	Connect the oscilloscope to TP15A (Right Channel). (Junction of
Ext. Trigger	------		R2K64 and R3A38)
Measuring		3.	Enter the Adjustment Mode and select the Audio Function.
	50mV/Div	4.	Verify that the Audio Function items are set to the data values given the
Range
			table below.
Input Signal	RF Monaural
		5.	Adjust Item “1 INP” for 1.55 ±0.06 Vp-p at TP15A.
	300 Hz modulation
Input Terminal	RF Input	6.	Connect the oscilloscope to TP14A. (Junction of R2K62 and R3A15)
		7.	Confirm that the left channel output at TP14A is 1.55 ±0.06 Vp-p.
		Note: Adjustment 2 (Stereo Separation) must be performed after this adjustment)
				SERVICE MODE	AUDIO Function
					Item	Abbrev.	Data
				Activate …….. MENU-0-1-5-7	1	INP	7
				Function …...………..AUDIO	2	AUT	0
				Item No. ……….…….VIDEO	3	WDE	16
				Adjust Data ….…….ADJUST	4	SPC	16
					15	MZX	1
				Save Data …. ………ENTER
					16	VZX	1
				Exit …………..MENU (twice)
					20	ATK	1

[Audio Circuit]	Purpose:	Adjust for optimum stereo separation.
2. Separation	Symptom:	Poor stereo separation

Measuring	Oscilloscope
Instrument
Test Point	TP14A, TP15A
Ext. Trigger	------
Measuring	10mV/Div
Range
Input Signal	RF Stereo
Input Terminal	RF Input

Note: This adjustment must follow Adjustment 1 (Input Level)

1.Supply a RF Stereo Signal to the Ant. A input.

•Left Channel = 300 Hz modulation

•Right Channel = no modulation signal

2.Connect the oscilloscope to TP15A (right channel). (Junction of R2K64 and R3A38)

3.Enter the Service Mode and select the Audio Function.

4.Adjust Item “3 WDE” for minimum signal at TP15A.

5.Change the modulation frequency to 3 kHz.

6.Adjust Item “4 SPC” for minimum signal at TP15A.

SERVICE MODE

Activate …….. MENU-0-1-5-7

Function …...………..AUDIO

Item No. ……….…….VIDEO

Adjust Data ….…….ADJUST

Save Data …. ………ENTER

Exit …………..MENU (twice)

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