Jvc THA 25 Service Manual
This is the 26 pages manual for Jvc THA 25 Service Manual.
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Extracted text from Jvc THA 25 Service Manual (Ocr-read)
Page 1
1-2 (No.MB143) SPECIFICATION Designs & specifications are subject to change without notice.Center unit (XV-THA25) Amplifier Front/Center/Rear 30 W per channel, min. RMS, driven into 6 Ω at 1 kHz, with no more than 10% total harmonic distortion Subwoofer 55 W, min. RMS, driven into 3 Ω at 100 Hz, with no more than 10% total harmonic distortion Audio Audio input sensitivity/Impedance (at 1 kHz) Analog input AUX ("AUDIO IN") 500 mV/47 kΩ Signal-to-Noise Ratio 68 dB Digital input* DIGITAL IN (OPTICAL) -24 dBm to -14.5 dBm (700 nm ±50 nm) * Corresponding to Linear PCM, Dolby Digital, and DTS Digital Surround (with sampling frequency-32 kHz, 44.1 kHz, 48 kHz) Video Color System NTSC/PAL Horizontal Resolution 480 lines Output Level VIDEO OUT (Composite) 1.0 V(p-p)/75 Ω S-VIDEO (Y):1.0 V(p-p)/75 Ω (C):0.286 V(p-p)/75 Ω COMPONENT VIDEO OUT Y 1.0 V(p-p)/75 Ω PB/PR 0.7 V(p-p)/75 Ω Tuner Tuning Range FM 87.50 MHz - 108.00 MHz AM 531 kHz - 1 602 kHz (at 9 kHz intervals) 530 kHz - 1 600 kHz (at 10 kHz intervals) Usable Sensitivity FM 8.0 dBf (0.9 µV/75 Ω) AM loop antenna 650 µV/m General Readable Discs DVD VIDEO, Video CD, Super Video CD, Audio CD, CD-R/RW (Audio CD, Video CD, Super Video CD, MP3, JPEG), DVD-R/RW (Video format) Power Requirements AC 110 V - 127 V/220 V - 240 V , Adjustable with the voltage selector, 50 Hz/60 Hz Power Consumption 110 W (at operation) 2 W (in standby mode) Dimensions (W × H × D) 360 mm × 65 mm × 404 mm Mass 6.3 kg Subwoofer (SP-WA25) Speaker 15 cm Bass-reflex, magnetically shielded Power Handling Capacity 55 W Impedance 3 Ω (min) Frequency Range 30 Hz to 200 Hz Dimensions (W × H × D) 210 mm × 382 mm × 338 mm Mass 6 kg Satellite Speakers (SP-XTHA25) Speaker 8 cm Bass-reflex, magnetically shielded Power Handling Capacity 30 W Impedance 6 Ω (min) Frequency Range 80 Hz to 20 kHz Dimensions (W × H × D) 105 mm × 114 mm × 116 mm Mass 640 g
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(No.MB143)1-3 SECTION 1 PRECAUTION 1.1 Safety Precautions (1) This design of this product contains special hardware and many circuits and components specially for safety purpos- es. For continued protection, no changes should be made to the original design unless authorized in writing by the manufacturer. Replacement parts must be identical to those used in the original circuits. Services should be per- formed by qualified personnel only. (2) Alterations of the design or circuitry of the product should not be made. Any design alterations of the product should not be made. Any design alterations or additions will void the manufacturers warranty and will further relieve the manufacture of responsibility for personal injury or property damage resulting therefrom. (3) Many electrical and mechanical parts in the products have special safety-related characteristics. These characteris- tics are often not evident from visual inspection nor can the protection afforded by them necessarily be obtained by us- ing replacement components rated for higher voltage, watt- age, etc. Replacement parts which have these special safety characteristics are identified in the Parts List of Ser- vice Manual. Electrical components having such features are identified by shading on the schematics and by ( ) on the Parts List in the Service Manual. The use of a substitute replacement which does not have the same safety charac- teristics as the recommended replacement parts shown in the Parts List of Service Manual may create shock, fire, or other hazards. (4) The leads in the products are routed and dressed with ties, clamps, tubings, barriers and the like to be separated from live parts, high temperature parts, moving parts and/or sharp edges for the prevention of electric shock and fire hazard. When service is required, the original lead routing and dress should be observed, and it should be confirmed that they have been returned to normal, after reassem- bling. (5) Leakage shock hazard testing After reassembling the product, always perform an isola- tion check on the exposed metal parts of the product (an- tenna terminals, knobs, metal cabinet, screw heads, headphone jack, control shafts, etc.) to be sure the product is safe to operate without danger of electrical shock.Do not use a line isolation transformer during this check. - Plug the AC line cord directly into the AC outlet. Using a "Leakage Current Tester", measure the leakage current from each exposed metal parts of the cabinet, particular- ly any exposed metal part having a return path to the chassis, to a known good earth ground. Any leakage cur- rent must not exceed 0.5mA AC (r.m.s.). - Alternate check method Plug the AC line cord directly into the AC outlet. Use an AC voltmeter having, 1,000Ω per volt or more sensitivity in the following manner. Connect a 1,500Ω 10W resistor paralleled by a 0.15µF AC-type capacitor between an ex- posed metal part and a known good earth ground. Measure the AC voltage across the resistor with the ACvoltmeter. Move the resistor connection to each exposed metal part, particularly any exposed metal part having a return path to the chassis, and measure the AC voltage across the resistor. Now, reverse the plug in the AC outlet and repeat each measurement. Voltage measured any must not exceed 0.75 V AC (r.m.s.). This corresponds to 0.5 mA AC (r.m.s.). 1.2 Warning (1) This equipment has been designed and manufactured to meet international safety standards. (2) It is the legal responsibility of the repairer to ensure that these safety standards are maintained. (3) Repairs must be made in accordance with the relevant safety standards. (4) It is essential that safety critical components are replaced by approved parts. (5) If mains voltage selector is provided, check setting for local voltage. 1.3 Caution Burrs formed during molding may be left over on some parts of the chassis. Therefore, pay attention to such burrs in the case of pre- forming repair of this system. 1.4 Critical parts for safety In regard with component parts appearing on the silk-screen printed side (parts side) of the PWB diagrams, the parts that are printed over with black such as the resistor ( ), diode ( ) and ICP ( ) or identified by the " " mark nearby are critical for safety. When replacing them, be sure to use the parts of the same type and rating as specified by the manufacturer. (This regulation dose not Except the J and C version) Good earth groundPlace this probe on each exposed metal part. AC VOLTMETER (Having 1000 ohms/volts, or more sensitivity) 1500 10W 0.15 F AC TYPE
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1-6 (No.MB143) SECTION 3 DISASSEMBLY 3.1 Main body section 3.1.1 Removing the top cover (See Figs.1 and 2) (1) From the both sides of the main body, remove the four screws A attaching the top cover. (See Fig.1) (2) From the back side of the main body, remove the four screws B attaching the top cover. (See Fig.2) (3) Take out the top cover in the upward direction while ex- tending the lower sections of the top cover in the direction of right and left. Fig.1 Fig.2 Top cover A A Top cover Rear panel B
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(No.MB143)1-17 5.2 DVD Servo parts 5.2.1 Initial operation after power ON (DVD Dual) (DVD single) Y Y 4 3 Y N N N Disc present or not Disc present POWER ON CD or DVD judgement DVD single or Dual layer judgementCD or CDRW judgement DVD single initial setting DVD Dual initial setting To Each disc playbackCD initial settingCDRW initial setting DVD SingleDualCD CD CDRW Is Tray closed?Tray close operation. about 3sec. Is Tray closed? Stop Close operation. Wait Open Command from MPEG Laser Off Monitor Display=NO DISC Pick up head ini t ial position.
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1-18 (No.MB143) 5.2.2 Play operation Play Disc Motor forced accellerationRepeat seveal timesChange Disc Type Focus Seach Track servo ON CLV servo ON Read TOC Automatic Adjustment Automatic Adjustment is done once when the disc is replaced Is focus servo on? Search Picture appears 6 7 8 5