HITACHI HRJ635
Service Manual

JVC HR-J635
Mechanism Adjustments Cont�d
TAPE INTERCHANGEABILITY ADJUSTMENT NOTE: This adjustment is extremely important. However, it is normally not required during routine service. Perform only after replacing major components (A/C head upper/lower drum assy, pole base assy, etc). Before using costly alignment tape use a spare tape and confirm correct operation of the tape transport. Tape pattern 1) Connect the oscilloscope to TP106(PB FM) on the PRE/REC board.Use TP11110.FF) on the PRE/REC board as a trigger. 2) Playback the SP stairstep portion of the alignment tape [MHPE].Confirm that the FM waveform appears as indicated in Fig. 2-7-1. 3) Set the manual tracking position by pressing the / I// button on the remote controller or TV PROG �-� and �+� buttons simultaneously. 4) Operate the tracking adjustment (press the TV PROG buttons during playback) and set for maximum playback FM waveform. 5) By operating the TV PROG buttonvary the FM waveform from maximum to minimum and vice versa to confirm that the waveform varies nearly in a flat shape as shown in Fig.2-7-1.

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3) Then slowly turn screw (3) counterclockwise to where the curling ceases. 2. Height 1) Connect CH-1 of a dual trace oscilloscope to Audio Out. 2) Connect CH-2 to TP11011 CTL PULSE) of the Main board assy and use the ALT mode. 3) Playback the SP stairstep portion of the alignment tape [MHPE]. 4) Adjust screws (1) (2) and (3) for maximum audio output and control pulse level. 3. Azimuth 1) Connect the oscilloscope to Audio Out. 2) Playback the SP stairstep portion of the alignment tape [MHPE]. 3) Adjust screw (2) 50 that the audio output is both maximum and with minimum fluctuation. A/C head phase (X-value) 1) Connect the oscilloscope to TP106 (PB FM) on the PRE/REC board.Use TP111(D.FF) on the PRE/REC board as a trigger. 2) Playback the SP stairstep portion of the alignment tape [MHPE]. 3) Set the neutral manual tracking position by pressing the /I// button on the remote controller or TV PROG �-� and �+� buttons simultaneously. 4) If adjustment is required,slightly loosen screws (4) and (5). Set A/C head positioning tool on the A/C head adjusting boss as indicated in Fig.2-7-6. Tension pole position 1) Set for playback mode using MECHANISM SERVICE MODE (See SECTION 1 DISASSEMBLY). 2) Slightly loosen the screw (A). 3) Turn the adjust pin so that the tension arm assy does not touch ø 2.5 pole on the outside. 4) Tighten the screw (A). 5) After adjustment,use the back tension cassette gauge and set for the playback mode. 6) Confirm reading of 29 to 46 g�cm. Fig. 3-2-2 PB switching point SIow tracking preset
Signal Mode Equipment Adjustment tool Specification � Tuner or colour bar � SP/LP, REC ¡ PB(SLOW) � TV-Monitor � Presetting unit [PTU94008] � Minimum noise

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11) If not maximum,slightly loosen the screws (4) and (5). Use the tool and adjust the head position for the nearest maximum point. Then tighten screws (4) and (5). LP mode auto tracking NOTE: Set VCR to the mode A by remote controller. 1) Connect the oscilloscope to TP106(PB FM) on the PRE/REC Board. Use TP111(D.FF) on the PRE/REC board as a trigger. 2) Playback the LP stairstep portion of the alignment tape [MHPE-L]. 3) Confirm the FM waveform of the oscilloscope screen until auto tracking action is over. 4) Twice press button �D� of the presetting unit [PTU94008]. 5) If the alignment tape ejects automatically, repeat the A/C head phase adjustment (Xvalue). 1) Record a monoscope signal in the SP mode. 2) Playback the recorded signal. 3) Press the �L� button of the presetting unit during playback. 4) Confirm that VCR mode becomes STOP mode. 5) Repeat steps (2) to (4) in the LP mode. SYSCON CIRCUIT Notes: Unless otherwise specified,aII measurement point and adjustment parts are located on the MAIN BOARD. When perform this adjustment, remove the MECHANISM assy. Timer clock
Signal Mode Equipment Measurement point Adjustment part Specification � No signal � EE � Frequency counter � TP702 round(SYS.CLK) � C701 (TIMER CLOCK) � 1024.008 ± 0.001 Hz [976.5549 ± 0.0010 used]

Fig. 3-2-1 Presetting unit

Fig. 2-7-3 8) Next playback the LP stairstep portion of the alignment tape [MHPE-L] and adjust the tracking control from maximum to minimum the FM waveform,confirm that FM waveform variation is always flat. 9) Record the signal and play it back in both of the SP and LP mode,confirm that the FM waveform is flat in both mode. 10)After adjustments,tighten the set screw of the guide rollers. 11)Confirm that the tape wrinking does not occur at the roller upper or lower limits as indicated in Fig.2-7-4.

Note: Set VCR to the mode A by remote controller. Use only buttons �B� and �C�, depressing other buttons during adjustment may cause adjustment errors. 1) Record a colour bar signal in the SP mode. 2) Playback recorded signal on the FWD slow mode. 3) Observe the display on the TV monitor and adjust for optimum noise condition (best tracking) by depressing �B or �C � buttons of the presetting unit. 4) Depress the STOP button. 5) Confirm that the bar noise is not visible on the TV monitor in the slow mode.

1) Connect the frequency counter to TP702 round and GND. 2) Connect the short wire between TP701 round and Vcc(5V). 3) Short the leads of capacitor C704 once in order to reset IC701. 4) Disconnect the short wire then connect it again quickly. 5) Adjust C701 for 1024.008 ± 0.001 Hz. (976.5549 ± 0.0010 usec) TUNER CIRCUIT Note: Unless otherwise specified, all measurement points and adjustment parts are located on the IF UNIT. RF AGC
Signal Mode Equipment Measurement point Adjustment part Specification � TV broadcasting � Tuner � TV monitor � IF UNIT � IF VR � Minimum noise

Fig. 2-7-8 Fig. 2-7-1 6) When the FM waveform does not remain flat during this process,first slightly loosen the set screw located at the bottom of the guide rollersUsing the guide roller adjustment tool (Roller driver), adjust the supply and take-up guide rollers (refer to Fig. 2-7-2) to obtain the correct waveform as indicated in Fig. 2-7-3. Fig. 2-7-6 5) Turn the tool first to position the NC head fully toward the capstan. Then gradually return it toward the drum and stop at the position of maximum FM waveform output level as shown in Fig.2-7-7. Fig. 2-7-4 A/C head height & azimuth NOTE: Temporarily set A/C head height as indicated in Fig. 2-5-4. Use spare tape to check the transport and confirm the tape is not scratched or damaged. 1. Tilt 1) Use spare tape and set for playback. 2) Turn screw (3) clockwise to where the tape curls just slightly at the TU guide pole bottom flange as shown in Fig. 2-7-5. Fig. 2-7-7 6) Tighten screw (5). Remove the tool and tighten screw (4). 7) Eject the SP alighnment tape IMHPE] and then re-insert the LP alignment tape [MHPE-L]. 8) Playback the LP stairstep portion of the alignment tape [MHPE-L]. 9) Set the neutral manual tracking position by pressing the /I// button on the remote controller or TV PROG �-� and �+� buttons simultaneously. 10) Confirm maximum playback FM waveform output level as shown in Fig.2-7-7. Take-up torque 1) Use the back tension cassette gauge and set for the playback mode. 2) Confirm reading of 60 to 100 g�cm. SERVO CIRCUIT Notes: Unless otherwise specified,all measurement point and adjustment parts are located on the MAIN BOARD. Set VCR to the mode A by remote controller. Use only buttons �0�, depressing other buttons during adjustment may cause adjustment errors. PB switching point
Signal Mode Equipment Measurement point � Alignment tape IMHPE]Stairstep � PB � Oscilloscope � J1411-pin 19 (VIDEO OUT) [TERMINAL BOARD] � TP111 (DRUM FF1,[PRE/REC BOARD] � Presetting unit [PTU94008] � 6.5 ± 0.5H

Note: Adjust IF VR (RF AGC) to correct for excess noise in the picture or when streaks cross interference occurs due to strong electrical fields. 1) Adjust IF VR to minimize noise or streaks on the TV screen. 2) Adjust for noisy picture with strong signal. Then adjust until noise just disappears. Select other channels to confirm proper pick-up of channels.

Fig.3-2-3 Presetting unit VIDEO CIRCUIT Notes: Unless otherwise specified,aIl measurement point and adjustment parts are located on the MAIN BOARD. Set VCR to the mode A by remote controller.

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Trigger slope (-) Adjustment tool Specification

Fig. 2-7-2 7) By pressing the TV PROG buttons several times, vary the FM waveform output from maximum to minimum land vice versa) graduallyand confirm that the variation proceeds in flat shape, as shown in Fig. 2-7-3. Fig. 2-7-5

1) Connect an oscilloscope to J1411-pin 19 (VIDEO OUT) and external trigger from TP111 (negative slope). 2) Playback the stairstep signal of the alignment tape. 3) Press the �0� button of the presetting unit. 4) Confirm that VCR mode becomes STOP mode.

Fig.3-3-1 Presetting unit Auto picture
Signal Mode Adjustment tool Specification � Monoscope � REC then PB SP/LP � Presetting unit[PTU94008] � STOP mode