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HITACHI VT F641 EUKN
General Information Also Covers VT M610 EUK, VT M631 EUK Matrix
Item See Model Book
5 5 4 4 Deck Exploded Parts View .......................................................... Paolina Mono Deck Parts List ............................................................................. Paolina Mono Mechanical Adjustments ...................................................... Turbo Mechanism Mechanical Alignments ........................................................ Turbo Mechanism

1
Service Modes
1. Special functions Erasing the EEPROM - Disconnect from mains - Push and hold down the Standby key, reconnect to mains and keep the Standby key depressed for a further 3 sec. All EEPROM data will then be erased and initialised (timer and transmitter channels). The internal processor RAM will also be erased, but the option codes, deck parameters and adjustment values are maintained. After changing the EEPROM or MOBO the following steps must be carried out: Step 40: Option code input Step 51: Gap position adjustment Step 52: `Studio Picture control' adjustment Step 53: Input of clock correction Step 60: Level adjustment - Stereo (optional) Step 61: Channel separation adjustment Stereo (optional) Step 62: Adjustment of Audio Linear Playback Level (optional) Step 99: Clock frequency output Video head cleaning With the recorder set to PLAY, the video heads can be cleaned by pressing the PLAY key again for more than 5 sec. The recorder then moves to STOP and the video head cleaning roll is pressed against the running head drum for 10 sec. The recorder automatically returns to PLAY. The display shows: Fig. 8 Fig. 4 Fig. 1 2. Service test program 2.3 Service mode functions 2.1 Introduction The software program for the control, deck and operating microprocessors includes a service test program. It was divided into the following steps, with the following `modes': Step 00: Display of mask version number Step 01: Check of the drive positions Step 02: Display of the deck - error codes Step 03: Deck - sensors and manual tracking Step 04: Display of operating hours counter Step 10: Operation without drive - dummy mode Step 40: Option code input Step 51: Gap position adjustment Step 52: `Studio Picture control' adjustment Step 53: Input of clock correction Step 60: Level adjustment - Stereo (optional) Step 61: Adjustment of channel separation Stereo (optional) Step 62: Adjustment of Audio Linear Playback Level (optional) Step 99: Clock frequency output In the service test program, all drive functions apart from the channel search and channel change mode can be carried out. The program position set before entering the service test program is maintained. 2.2 Activating the service test program Press and hold down the STOP key on the remote control. Then press the PLAY key on the recorder and keep it depressed for at least 5 sec. The STOP key on the remote control may Endurance test In the service test program, the recorder can be endurance tested. For this purpose, use a cass~te and activate "PLAY" or "REC". The functions are then repeated continuously. In RECORD, the recorder does not move to EJECT at the tape end, but to REWIND, after which it starts to RECORD again. This test serves to detect intermittent faults. The last error is stored in the EEPROM. (The fault remains stored even after a power failure). The endurance test is ended by pressing STOP or leaving the service test program. To leave the service program, press the STANDBY key or disconnect recorder from mains. Table of drive positions:
Status Eject Index Stop Play Reverse Position (FTA dec) 007+2/-2 191+0/-2 200+4/-4 213+4/-4 237 +2/-0

be released whilst the PLAY key on the recorder is pressed. The service test program can be selected in any operating mode apart from the channel search, install, clock set-up and cassette length calculation mode. The recorder and all drive functions are fully operational in the service mode. The display shows, for instance:

Checking the drive function Loading and unloading time The signal (ETA) of the photoelectric barrier which controls the revolutions of the loading motor is used as a reference for the loading and unloading time. Fig. 6 The mode can be left again by pressing the SELECT key on the remote control. The currently selected position number appears and flashes on the display. Stopping of supply or take-up reels The tacho signals of the left (WTL) and right (WTR) winding disks are used as control reference. Stopping of head drum motor This is monitored with the PG/FG signal. The signal is discharged from the e.m.f. of the nonconducting spools of the head cylinder motor, showing the position of the head cylinder. Fig. 7 A step between 00 and 99 can now be selected. Step 01: Checking the drive positions By pressing the SELECT key whilst Step 01 is flashing, the drive position appears on the display. The FTA signal from the photoelectric barriers which controls the revolutions of the loading motor is used to check the drive condition. The drive position is shown as a 3-digit decimal number by counting the FTA pulses on the display. (e.g. 213 = Play) Capstan motor fault This is monitored with the FGD signal. If one of the above sensor signals is not available, the recorder tries to put the lift into the "EJECT" position. Explanation of deck error codes and deck error status The last error code is stored and remains in the EEPROM, even if the recorder is disconnected trom the mains. The error code can be erased by pushing the CLEAR button on the remote control. The display shows, for instance:

Fig. 2 By pressing the SELECT key on the remote control, all step modes may be left and the currently selected step number appears and flashes.

Recommended Safety Parts
Item
1001 1350 1351 1352 1353 1355 1356 3252 3361 3384 3392 3393 3414 3415 3440 5080 5150 5300 5352 5353 5355 7350 7351

Part No.
R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 R4822 267 10577 252 11234 071 55001 071 55001 070 31252 252 11235 252 11235 117 11593 052 10479 052 10101 053 21335 053 21335 052 10109 052 10109 052 10228 157 11226 157 53906 157 53005 157 10454 146 10786 157 53005 130 63794 209 32126 321 10886 321 10249

Description
MAINS PLUG Fuse 100 mA Fuse 500 mA Fuse 500 mA Fuse 1.25 A Fuse 1.0 A Fuse 1.0 A 22 R 47 R 0,33W 100 R 0,33W 3,3 M 0,5W 3,3 M 0,5W 10 R 0,33W 10 R 0,33W 2,2 R 0,33W 47uH 5% 47uH 10% 0pH33 20% LINE FILTER SRW32ES-E01 0pH33 20% STP3NA60 SOC1012T MAINS CORD (+FUSE) for UK MAINS CORD

Fig. 3 Other service steps are selected with the UP and DOWN keys or the numerical remote control keys. By pressing the SELECT key on the remote control whilst the Step is flashing, the respective mode can be entered or left. If a step is selected to which no mode is assigned, the displays shows - - and flashes.

Fig. 10 The left digit shows the error: (e.g.: Error 2 = Capstan error) Error table: 0 1 2 3 4 5 6 no error threading error no capstan pulses tape broken no pulses left reel no pulses right reel head motor error

AV Sockets PCB Diagram

Function of the Init switch: The diagram shows the function of the nit switch, depending on the position of the deck. The number of ETA pulses is important for theposition of the drive.

The 3 digits on the right represent the deck error condition: (e.g.: 053 = during Play) 012 Standby 014 Autotracking 031 Play-3 034 Slow reverse 041 Still Picture 042 Fast 044 Play-9 045 Eject 046 Play9 047 Play-1 048 Pause 050 Rewind 052 Wind 053 Play 054 Stop out 055 Record 112 lndex next 113 Index previous 114 VlSS write 115 Viss erase 125 Tuner-Stopout 126 Auto Remain Funct. 130 ATTS Function 168 Frame+ 169 Frame-

Fig. 5 2.4 Description of steps with modes: Step 00: Display of mask version number After activating the service test program, step 00 and the mask version number are automatically displayed. Fig. 9 Step 02: Display of the deck error codes By pressing the SELECT key whilst Step 02 is flashing, the deck error code is shown on the display.

HITACHI VT F641 EUKN
Service Modes Cont'd
170 171 172 173 174 175 196 197 199 202 206 211 212 215 216 217 218 219 220 222 223 238 239 246 247 248 249 250 253 Play-11 Play-7 Play-5 Play5 Play7 Play11 Tuner-Eject Standby Eject Audio Dubbing Audio Dubb. Pause Reset Tapecounter Slow motion 1/24 Slow motion 1/14 Slow motion 1/7 Slow motion 1/2 Slow motion -1/24 Slow motion -1/14 Slow motion -1/7 Slow motion -1/2 Edit Record Align of Gap Pause SPC align Edit Pause Slow motion 1/10 Slow motion 1/18 Slow motion -1/10 Slow motion -1/18 Key Released Enter the mode by pressing the SELECT key. The motors are then switched off and the sensors will be ignored by the deck microprocessor. The drive can now be dismantled from the motherboard (see dismantling instructions). Only install drive if recorder is disconnected from mains. For signal tracking, the recorder can be set to all drive conditions, i.e. signal electronics, audio and IO processing are switched to the respective operating mode.

2
using the numerical keys. --Insert a test cassette (e.g. 4822 397 30103) with the standard video signal in the VCR. --By pressing the SELECT key whilst step 51 is flashing, the automatic adjustment is triggered and stored in the EEPROM. After a correct adjustment, the display shows 1; 0 when incorrect. To leave the step, press Select.

Cabinet Exploded Parts View

Fig. 17 Fig. 13 Causes of incorrect adjustment: Incorrect standard video signal. Scanner fault. Microprocessor fault. Step 52: "Studio Picture control" adjustment Purpose: Adjustment of the reference level for the SPC. Symptom if incorrectly set: The picture is played back at a lower resolution than would be possible.

START mit switch (INIT) END record protection (RECP) DEC loading pulses (FTA) Step 40: Option code input If a new EEPROM is installed in the course of repairs, it must be initialised By pressing the SELECT key whilst step 40 is flashing, the decimal option A appears in the display.

The error code can be reset in this step with the CLEAR key. Fig. 14 Step 03: Deck sensors and manual tracking By pressing the SELECT key whilst step 03 is flashing, the deck sensors will be displayed in one digit as either 1 or 0. By entering a 3-digit decimal code, the correct features are set. These codes are shown on the type-plate of the recorder. After pressing the OK key on the remote control, the entered code is saved. The display shows OK for approx. 3 sec. and then the stored value in decimal format. By pressing the UP and DOWN keys, the available options (A to E) can be selected. The display shows the last stored value in decimal format.

Table 1 - Video signal via Scart or aerial - Enter the service test program and, whilst the step is flashing, input the step number 52, using the numerical keys. - Insert cassette (not a SVHS cassette). - By pressing the SELECT key whilst step 52 is flashing, the recorder makes a recording in SP mode (approx. 10 sec.) and in LP mode (approx. 10 sec.), rewinds and carries out a playback with automatic adjustment. - After a correct adjustment, the display shows 1 and 0 for incorrect adjustments.

Fig. 11 START init switch (INIT) END record protection (RECP) DEC Loading pulses (FTA) In the service test program, the tracking is always in the centre position. Only in this step can the value tor the required tape running sefting be changed, manually in the PLAY function with the UP / DOWN keys. After leaving the mode with the SELECT key, the tracking value always resets itself to the centre position and cannot be changed. Step 04: Display of the operating hours counter: By pressing the SELECT key whilst step 04 is flash jng, the operating hours counter shows how many hours the head disk has turned. The hours are displayed as a 4-digit decimal number.

Fig. 15 In case of an invalid entry (value >255) the activation of the OK key causes the content of the last stored option to be displayed and OK does not appear in the display. Depending on the model, some bits are software or default protected and cannot be changed by an entry. In this case, the display shows OK, but the display returns to the default value.

Fig. 18 To leave the step press SELECT. Step 53: Inputting the clock correction Before carrying out step 53, the correction value must be established in step 99. By pressing the SELECT key whilst step 53 is flashing, the display shows, for instance:

Mechanical Parts - Cabinet
Item
1 2 6 7 8 20

Part No.
R3103 138 86070 R3103 141 22000 R3103 184 00830 R3103 100 42400 R3103 100 42530 R3103 138 87120 R3103 138 86820 R3103 138 87110 R3103 178 21210 R3103 178 20970 R3103 178 21220 R3103 111 02450 R3103 144 23460 R3112 400 40220 R3103 107 61760 R3103 10041320 R3103 104 20410 R8622 661 73301 R3103 166 18990 R3103 166 18740 R3103 166 18970 R3103 110 01280

Description
Frame CINCH Bracket Foot Screw 3,5X16 Screening screw Control panel [VT-F641EUKN] Control panel [VT-M610EUK] Control panel [VT-F631EUK] Lift flap [VT-F641EUKN] Lift flap [VT-M610EUK] Lift flap [VT-F631EUK] Leg spring Cover lacquered Screw 3,5X10 Distance holder deck Screw P2,9X12 Distance holder MOBO Remote RT173/301 Direction for use GB [VT-F641EUKN] Direction for use GB [VT-M610EUK] Direction for use GB [VT-F631EUK] Wordmark HITACHI

Fig. 16 3.Adjustments in the service test program Step 51: Setting the gap position (GAP) Purpose: To determine the correct head switching point during playback. Fig. 19 Using the numerical keys of the remote control, the established correction value from Step 99 is entered as a 3-digit number (value must be between 0 and 255). After pressing the OK key on the remote control, the entered code is stored, the display shows OK for approx. 3 seconds and then the stored value in decimal format.

20/6

Fig. 12 Step 10: Operation without drive - dummy mode Before activating this mode with the SELECT key, the recorder must be in the EJECT position. Symptom if incorrectly set: Head switching fault and/or vertical picture flickers. -- Enter the service test program whilst step display is flashing, and enter the step number

20/7 22 23 30 36 60 151 152

168

HITACHI VT F641 EUKN
Service Modes Cont'd
-- Connect Millivoltmeter to Scart 1 Pin 3 (Audio out left). -- The noise amplitude on Scart 1 Pin 3 (Audio out left) can be adjusted to the lowest value by pressing the UP(+) or DOWN (-) keys. (The amplitude changes by 0.1 dB each time the key is pressed). The range is shown in the display with the numbers 0.49. - The value is automatically stored in the EEPROM each time the button is pressed. Deviation = 1x106x (fmess-fnom) /fnom

3
Determining the correction value for Step 53: Correction value = Deviation / 0.763 + 128 (round off to whole number) The calculated correction value must be between 0 and 255 (change quartz otherwise), and must be entered in Step 53 and saved. This Step can only be left by performing a mains reset, after which the service program must be entered again before Step 53 can be called up. Example: fmess =2047.97Hz fnom=2048.00Hz Deviation = 1x106x (2047.97- 2048) / 2048 = -14.648 Correction value = -14.648 / 0.763 +128 = 108.80 = 109 (See Fig. 24)

Fig. 20 In case of an invalid entry (value >255), the activation of the OK key causes the content of the last stored value to be displayed and OK does not appear in the display. To leave the step press Select. Step 60: Level adjustment of Stereo TDA9840 (only for stereo units) Purpose: Amplification adjustment of stereo demodulator TDA9840 [7780]. Symptom if incorrectly set: Sound is too low or too loud

Fig. 22 After leaving the step with SELECT, the last value remains stored in the EE-PROM. Step 62: Adjustment of the Audio-LinearPlayback level (only for stereo units) Purpose: Adjustment of the amplification of the audio linear playback level TDA96O4H [7850]. Symptom if incorrectly set: The linear playback sound is too low or too loud.

Adjustments
Test equipment: 1. Dual-trace oscilloscope Voltage range 0.001 50 V/div Frequency : DC -~ 50 MHz Probe :10:1,1:1 2. DVM (Digital voltmeter) 3. Frequency counter 4. Sinus generator Sinus : 0~50 MHz 5. Test pattern generator 6. VHS AlignmentTape 4822 397 30103 How to read the adjustment procedures:

Table 2 By pressing the SELECT key whilst step 60 is flashing, the output select is switched to stereo and the display shows, for instance: Table 4 By pressing the SELECT button whilst step 62 is flashing, the output select is switched to Mono and the display shows, for instance: Fig. 21 --Connect the millivoltmeter to Scarti pini (Audio out right). -- The level on Scart 1, Pin 1 (Audio out) can be adjusted to the set value by pressing the UP (value increases) or DOWN key (value decreases). (The amplitude changes by 0.5 dB each time the key is pressed). The range is shown in the display with the numbers 1-9. -- The value is automatically stored in the EEPROM each time the key is depressed. After leaving the step with SELECT, the last value will be stored in the EE-PROM. Step 61: Adjustment of stereo channel separation Stereo TDA9840 Purpose: Adjustment of channel separation of the stereo demodulator TDA9840 [7780]. Symptom if incorrectly set: Crosstalk between left and right channel.

Fig. 24 2.1 PAL chrominance record current adjustment [3007]: Connect resistor R3031 on the emitter side (T7006) with 5VASW of coil L5001.

Fig. 23 --Make a recording of the audio signal on E1. --Connect the millivoltmeterto Scarti Pin 1 (Audio out) and play the recording back. --The level on Scart 1, Pin 1 (Audio out) can be adjusted to the set value by pressing the UP (value increases) or DOWN keys (value decreases). (The amplitude changes by 1 dB each time the key is pressed). The range is shown in the display by the numbers 0.15. - The value is automatically stored in the EEPROM each time the button is pressed. Step 99: Clock frequency output Purpose: Setting the exact clock function. Symptom, if incorrectly set: The clock is too fast or too slow. After entering with SELECT, the display is switched off and no further function can be carried out. At the HEST measuring point [7201 pin 80], the uncorrected clock frequency of approx. 2048 Hz is always output. Measure the output frequency with the calibrated counter (minimum resolution of 6 digits) and note down the value (fmess). Fig. 25 1. Power supply - QMB (PS) Service tasks after repairing the power supply: 1.1 Setting the output voltage +5VASW [3379]: Purpose: To set the correct supply voltage. Symptom, if incorrectly set: VCR functions are not operating correctly. Before commencing adjustment: Call the service test program and enter Step 10 (Dummy mode). Remove the drive from the motherboard. Control the luminace amplitude on TPR3031: Fig. 26 2.2 SECAM chrominance record current adjustment [3159]: Connect resistor R3031 on the emitter side (T7006) with 5VASW of coil L5001. Table 5 2. Video signal processing-QMB (VS,AL,l/O) Service tasks after replacement of ICs 7007, 7110: Purpose: To set the optimum record PAL or SECAM chroma level. Symptom, if incorrectly set: If the record level is too high, beats may appear on the picture. If the level is too low, the colour may be degraded. Table 7 Fig. 27 3. Audio linear - QMB (VS, AL, I/O) Service tasks after replacement of coil L5603, IC7007 or the audio heads: 3.1 Adjusting the erasing frequency [5603]: Purpose: To set the correct recording erasing frequency. Symptom, if incorrectly set: Erasing frequency or its harmonics cause audio faults.

Table 9 Continues on next page...

Table 3 Determining the deviation (in ppm): By pressing the SELECT key whilst step 61 is flashing, the output select is switched to stereo and the display shows, for instance: fmess...measured frequency fnom...set frequency (2048,000 Hz)

Table 6

Table 8

HITACHI VT F641 EUKN
Adjustments Cont'd
3.2 Adjustment of playback amplitude [3160]: (mono only) Purpose: To set audio part amplification Symptom, if incorrectly set: Playback sounds too faint or too loud. Table 13 4.2 SECAM band 1 - AFC adjustment [3748]: (SECAM L/L' only) Before commencing ad]ustment: -- Switch VCR to SECAM with SYSTEM key. Table 10 3.3 Adjustment of bias current (3618]: Purpose: To set the optimum record bias current. Symptom, if incorrectly set: If the audio level is too high, the higher frequencies of the linear sound are too low. If the level is too low, the higher frequencies are too strong and sound distortions inrease. Table 14 4.3 Phase offset adjustment (3743]: (TDA9800T only) After replacement of the ICTDA9800T [7720], the potentiometer pos. 3748 has to be removed from the motherboard. The demodulator IC TDA9800T [7720] is automatically adjusted to a default value. 4.4 HF - AGC adjustment [3742]: Service tasks after replacement of ICs 7720, 7721 or TUMOD: Table 11 Checking the `bias'adjustment: After the bias has been adjusted to the indicated level, record some music, play back the recording, and adjust the audio switch to "MONO". Only use brand name cassettes, but not chrome dioxide tapes. Check if sufficient treble is reproduced and for any audio distortion. In case of insufficient treble, reduce `bias' current a little. In case of excessive distortion, increase `bias' current a little. 4. Front End - QMB (VS, AL, I/O) Service tasks after replacement of ICs 7720, 7721, coil L5725 and TUMOD: 4.1 AFC Adjustment: Purpose: Correct adjustment of demodulatorAFC - circuit Symptom, if incorrectly set: Bad or disturbed TV channel reception. 4.1.1 PAL - AFC adjustment (5725]: Purpose: Set amplifier control. Symptom, if incorrectly set: Picture jitter if input level is too low and picture distortion if input level is too high. 4.1.2 PAL/SECAM - AFC adjustment [5725]:

4
If the adjustment is correct the signal at pin 1 of SFW [1720] must be smaller than the input signal amplitude by at least 5 dB. Software adjustments in the service test program 5. Deck electronics - QMB (DE, DC) Service tasks after replacement of the head drum or EEPROM: 5.1 Software adjustment of gap positions: Information about this adjustment is contained in the Fault Locating document, Chapter 2-20, and in the service test program in Step 51. 5.2 "Studio Picture control" adjustment: Information about this adjustment is contained in the Fault Locating document, Chapter 2-20, and in the service test program in Step 52. 6. Stereo demodulator TDA9840 - QMB (FV) Service tasks after replacement of IC7780 or the EEPROM: 6.1 Stereo level adjustment [7780]: Information about this adjustment is contained in the Fault Locating document, Chapter 2-20, in the service test program in Step 60. 6.2 Stereo channel separation adjustment [7780]: Information about this adjustment is contained in the Fault Locating document, Chapter 2-20, in the service test program in Step 61. 7. Audio HIFI TDA9604H - QMB (AF) Service tasks after replacement of the audio heads, IC 7007 or the EEPROM: 7.1 Audio Linear playback level adjustment TDA9604H (7850]: Information about this adjustment is contained in the Fault Locating document, Chapter 2-20, in the service test program in Step 62. 8. Display Control - QMB (DE, DC) Service tasks after replacement of the clock quartz [1297] or the EEPROM: 8.1 Clock frequency adjustment: The clock is corrected via software with the measurement of a frequency at the HEST measuring point [7201, pin 80] and computation of a correction factor. Information about this adjustment is contained in the Fault Locating document, Chapter 2-20, in the service test program in Steps 53 and Step 99.

Wiring Diagram

Table 15 4.5 Attenuating the 40.4 MHz [5721]: (SECAM only) Service tasks after replacement of coil 75721: Purpose: To attenuate the band I carrier rests. Symptom, if incorrectly set: Bad picture quality when the filter attenuates the picture carrier (38.9MHz).

Fig. 28

Table 12 Table 16

HITACHI VT F641 EUKN
Deck Electronics Diagram

5

HITACHI VT F641 EUKN
Display Control Diagram

6
Waveforms

HITACHI VT F641 EUKN
Scart Diagram

7
Head Amp Diagram

HITACHI VT F641 EUKN

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HiFi Audio Diagram

HITACHI VT F641 EUKN

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Nicam Diagram

HITACHI VT F641 EUKN

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OSD , VPS, PDC Diagram

HITACHI VT F641 EUKN

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Power Supply Diagram

HITACHI VT F641 EUKN

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Secam Processing Diagram

HITACHI VT F641 EUKN

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Supply Voltages & Bus Diagram

HITACHI VT F641 EUKN

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Tuner IF Diagram

HITACHI VT F641 EUKN

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Video Processing Diagram