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Hitachi VT-MX425AW Video cassette recorder
Manufacturer:
Model:
VT-MX425AW
Date:
1997
Class:
Type:
SubType:
Service Manual
Manual type:
Service Manual
Pages:
88
Size:
10.01 Mbytes (10497521 Bytes)
Language:
english
Revision:
Manual-ID:
4719E
Date:
01 September 1997
Quality:
Scanned document, all readable.
Upload date:
16 April 2017
MD5:
aba58be66994c71ca2543ad14086bd71
Downloads:
1896

Information

CHAPTER 1 GENERAL INFORMATION C O N TEN1. Specifications ... 2. Comparison with Previous M od el ... 3. Comparison of Main Control IC s ... 4. Tips for Servicing ... 4-1. Trouble Display F unction ... 4-2. How to Remove the Cassette when a Malfunction Has Occurred in the Mechanism 4-3. Instructions on U s e ... ■ 1-1 ■ 1-2 ■1-3 ■ 1-4 ■1-4 ■ 1-5 ■ 1-6 CHAPTER 2 DISASSEMBLY 1. Before Starting Disassem bly ... 2-1 2. Disassembly M eth od ... 2-1 Parts Hierarchy C h a rt ... 2-1 Disassembly Procedure D iagram s ... 2-2 2-1. Top cover, front panel, rear panel and US-FL m echanism ... 2-2 2-2. Cassette door and insulator ... 2-2 2-3. SHU board ... 2-3 2-4. Front piece and LCD board ... 2-3 2-5. US mechanism/MAS board assembly ... 2-3 2-6. Separation of MAS board from US mechanism ■■■■ 2-4 2-7. Procedure to remove only the US m echanism ... 2-4 3. Cautions When Reinstalling the US Mechanism ... 2-5 CHAPTER 3 ELECTRIC CIRCUIT ADJUSTMENT Service Position 1. Servicing position during electrical adjustm ent ... 3-1 2. Servicing positions when repairing and checking circu its ... 3-1 2-1. Procedure to set the LCD and SHU board to the servicing positions ... 3-1 2-2. Procedere to set the MAS board to the service position ... 3-1 3. Be careful of electric shocks ... 3-1 Electrical Circuit Adjustment 1. Test equipment/jigs necessary for adjustm ent ... 3-2 2. Cautions on adjustm ent ... 3-2 3. Tips for adjustm ent ... 3-2 3-1. Procedure to reset the main microprocessor ... 3-2 3-2. Procedure to switch off the blue background function ... 3-2 3-3. Procedure to obtain the EP head playback mode (X-value adjustment test m o d e ) ... 3-2 4. Connections of test equipm ent ... 3-2 5. Test Points and Adjustment points ... 3-3 TS 6. Servo Circuit Adjustm ents ... 6-1. Switching point adjustm ent ... 6-2. X-value adjustm ent ... 6-3. Vertical jitter adjustment ... 6-4. Forward slow tracking preset adjustm ent ... 6-5. Reverse slow tracking preset adjustm ent ... 7. Audio/MTS Circuit Adjustm ents ... 7-1. Hi-Fi audio playback level check ... 7-2. MTS input level adjustm ent ... 8. List of Data in EEPROM and Initial Settings ... 9. List of Hidden C om m ands ... 9-1. Mode setting commands during adjustm ent ... 9-2. EEPROM initialization com m ands ... 10. Initial Settings of IC903(EEPROM) ... 11. Caution When Replacing IC903(VCR EEPROM)- ■3-4 ■3-4 •3-4 •3-5 ■3-5 ■3-5 ■3-6 ■3-6 ■3-6 ■3-7 ■3-7 ■3-7 ■3-8 ■3-8 •3-8 CHAPTER 4 EXPLODED VIEWS ] 1. CABINETS E C TIO N ... 4-1 2. US-MECHA NISM (TOP VIEW) SECTION ... 4-2 3. US-MECHA NISM (BOTTOM VIEW) SECTION ... 4-3 4. US-FL MEC HANISM SECTION ... 4-4 CHAPTER 5 REPLACEMENT PARTS LIST ] 1. MECHANIS M PARTS L IS T ... 5-1 2. ELECTRIC/L PARTS L IS T ... 5-2 CHAPTER 6 SCHEMATIC, CIRCUIT BOARD AND BLOCK DIAGRAMS Schematic and circuit board diagrams [VT-MX223AW,MX425AW] CONNECTION DIAGRAM ... 6-1 SCHEM ATIC/CIRCUIT LCD DISPLAY[LCD] ... 6-2 / 6-18 LCD DISPLAY GRID T A B LE ... -6 -3 / - SHUTTLE SW ITCH[SHU] ... 6-3 / 6-18 CYL. MOTOR DRIVE ... 6-4 / - CAPSTAN MOTOR ... 6-4 / - MECHANISM SENSOR[MAS] ... 6-5 / 6-20 MAIN CONTROL[MAS] ... 6-6 / 6-20 MTS/JACK[MAS] ... 6-8 / 6-20 PREAMP/FM AUDIO[MAS] ... 6 -1 0 /6 -2 0 LUMA/CHROMA,LINEAR AUDIOfMAS] ... 6-14 / 6-20 SWITCHING REGULATOR[MAS] ... 6 -1 6/6 -20 SERVO WAVEFORMS ... 6-5 LUMA/CHROMA WAVEFORMS ... 6-13 [VT-FX621AW] CONNECTION DIAG RAM ... 6-51 SCHEMATIC/CIRCUIT LCD DISPLAY[LCD] ... 6-52 / 6-68 LCD DISPLAY GRID T A B LE ... 6-53 / - CYL. MOTOR DRIVE ... 6-54 / - CAPSTAN M OTOR ... 6-54 / - MECHANISM SENSOR[MAS] ... 6-55 / 6-70 MAIN CONTROL[MAS] ... 6-56 / 6-70 MTS/JACK[MAS] ... 6-58 / 6-70 PRE AMP/FM AUDIO[MAS] ... 6-60 / 6-70 LUMA/CHROMA,LINEAR AUDIO[MAS] ... 6-64 / 6-70 SWITCHING REGULATOR[MAS] ... 6 -6 6 /6 -7 0 SERVO W AVEFORMS ... 6-55 LUMA/CHROMA W AVEFORM S ... 6-63 Block diagrams 1. MAIN C O N TR O L ... 6-101 2. S E R VO ... 6-103 3. A U D IO ... 6-105 4. VIDEO ... 6-107 5. REGULATOR ... 6-109 Microprocessor Pin Function Tables 1. LCD Driver (IC 701) ... 6-110 2. Main uP (IC 9 0 1 ) ... 6-111 CHAPTER 7 TROUBLE DISPLAY AND . TROUBLESHOOTING Trouble Display Function ... 7-1 Troubleshooting According to Malfunction Display .. 7-2 Troubleshooting the Switching Regulator ... 7-6

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