JVC KV-V8 service manual Precaution, Required test equipments, Required adjustment tools

SECTION 3

ELECTRICAL ADJUSTMENT

3.1Precaution

The following adjustment procedures are not only necessary after replacement of consumable mechanical parts or board assemblies, but are also provided as references to be re- ferred to when servicing the electrical circuitry.

In case of trouble with the electrical circuitry, always begin a service by identifying the defective points by using the meas- uring instruments as described in the following electrical ad- justment procedures. After this, proceed to the repair, replace- ment and / or adjustment. If the required measuring instru- ments are not available in the field, do not change the adjust- ment parts (variable resistor, etc.) carelessly.

3.1.1 Required test equipments

•Color (colour) television or monitor

•Oscilloscope: wide-band, dual-trace, triggered delayed sweep

•Digit-key remote controller (provided)

3.1.2 Required adjustment tools

Jig RCU	Alignment tape	Alignment tape
PTU94023B	(SP, stairstep, NTSC)	(EP, stairstep, NTSC)
	MHP	MHP-L
Alignment tape	Alignment tape	Alignment tape
(SP, stairstep, PAL)	(LP, stairstep, PAL)	(SP, color (colour) bar, NTSC)
MHPE	MHPE-L	MH-1
Alignment tape	Alignment tape	Alignment tape
(EP, color (colour) bar, NTSC)	(SP, color (colour) bar, PAL)	(LP, color (colour) bar, PAL)
MH-1L	MH-2	MH-2L

3.1.3 Switch settings and standard precautions

The SW settings of the VCR and the standard precautions for the electrical adjustments are as follows.

•When using the Jig RCU, set its custom code to match the custom code of the VCR.

Jig RCU

[Data transmitting method] Depress the “ ” ( 3 ) button after the data code is set.

CUSTOM CODE	INITIAL MODE
43: A CODE

53:B CODE DATA CODE

Fig. 3-1-3a Jig RCU [PTU94023B]

•Unless otherwise specified, all measuring points and adjustment parts are located on the Main board.

•When checking the operation or performing adjust- ments to the VCP main unit, it is necessary to connect the power cable (Car Cable) to the VCP main unit so that DC power is supplied. Also, when using the re- mote control unit, it is required to connect the IR re- ceiver. (by using either the provided or operational ac- cessories)

3.2Servo circuit

3.2.1 Switching point

Signal	(A1)	• Stairstep signal
		- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
		[KV-V8E]
	(A2)	• Alignment tape (SP, stairstep, PAL) [MHPE]
		- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
		[KV-V8J]
	(A2)	• Alignment tape (SP, stairstep, NTSC) [MHP]
Mode	(B)	• PB
Equipment	(C)	• Oscilloscope
Measuring point	(D1)	• VIDEO OUT terminal (75Ø terminated)
	(D2)	• TP106 (PB FM)
External trigger	(E)	• TP111 (D.FF)
Adjustment part	(F)	• Jig RCU: Code “5A”
		[KV-V8E]
Specified value	(G)	• 6.5 ± 0.5 H (SP, stairstep, PAL) [MHPE]
		- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
		[KV-V8J]
	(G)	• 6.5 ± 0.5 H (SP, stairstep, NTSC) [MHP]
Adjustment tool	(H)	• Jig RCU [PTU94023B]

(1)Play back the signal (A1) of the alignment tape (A2).

(2)Apply the external trigger signal to D.FF (E) to observe the VIDEO OUT waveform and V.PB FM waveform at the measuring points (D1) and (D2).

(3)Set the VCR to the manual tracking mode.

(4)Adjust tracking so that the V.PB FM waveform becomes maximum.

(5)Set the VCR to the Auto adjust mode by transmitting the code (F) from the Jig RCU. When the VCR enters the stop mode, the adjustment is completed.

(6)If the VCR enters the eject mode, repeat steps (1) to (5) again.

(7)Play back the alignment tape (A2) again, confirm that the switching point is the specified value (G).

Trigger point		V.sync
	Switching point

V. rate

Fig. 3-2-1a Switching point

3-1