DAEWOO ELECTRONICS AMI-921DP Service Manual

Specifications

Brand:	DAEWOO ELECTRONICS
Category:	Stereo System
Model:	AMI-921DP (Service Manual)
File Type:	PDF
File Size:	—
Pages:	29

Download

Download DAEWOO ELECTRONICS AMI-921DP PDF Manual (29 pages)

Read Online

Read the DAEWOO ELECTRONICS AMI-921DP Service Manual online using the built-in PDF viewer.

Text of the manual

SAFETY PRECAUTIONS ................................................................................................. 2 ADJUSTMENTS............................................................................................................. 4 EXPLODED VIEW AND PARTS LIST ................................................................................ 7 WIRING DIAGRAM ..................................................................................................... 9 BLOCK DIAGRAM ...................................................................................................... 10 SCHEMATIC DIAGRAM ............................................................................................... 11 POWER / AMP ...................................................................................................................................11 CD ...................................................................................................................................................12 TUNER ...............................................................................................................................................13 TAPE .................................................................................................................................................16 CONTROL .........................................................................................................................................17 PCB PATTERN LAYOUT ................................................................................................. 18

WARNING: TO PREVENT FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE

THIS APPLIANCE TO RAIN OR MOISTURE. CAUTION :TO REDUCE THE RISK IF ELECTRIC SHOCK, DO NOT REMOVE COVER (OR BACK). NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL. THIS SYMBOL IS INTENDED TO ALERT THE USER TO THE PRESENCE OF UNINSULTED "DANGEROUS VOLTAGE" WITHIN THE PRODUCT'S ENCLOSURE THAT MAY BE SUFFICIENT MAGNITUDE TO CONSTITUTE A RISK OF ELECTRIC SHOCK TO PERSONS. THIS SYMBOL IS INTENDED TO ALERT THE USER TO THE PRESENCE OF IMPORTANT OPERATING AND MAINTENANCE (SERVICING) INSTRUCTIONS IN THE LITERATURE ACCOMPANYING THE APPLIANCE. CAUTION TO PREVENT ELECTRIC SHOCK, DO NOT USE THIS POLARIZED AC PLUG WITH AN EXTENSION CORD, RECEPTACLE OR OTHER OUTLET UNLESS THE BLADES CAN BE FULLY INSERTED TO PREVENT BLADE EXPOSURE. LASER SAFETY THIS UNIT EMPLOYS A LASER. ONLY QUALIFIED SERVICE PERSONNEL SHOULD REMOVE THE COVER OR ATTEMPT TO SERVICE THIS DEVICE DUE TO POSSIBLE EYE INJURY. CAUTION : USE OF ANY CONTROLS, ADJUSTMENTS, OR PROCEDURES OTHER THAN THOSE SPECIFIED HEREIN MAY RESULT IN HAZARDOUS RADIATION EXPOSURE. CAUTION : TO PREVENT ELECTRIC SHOCK, MATCH WIDE BLADE OF PLUG TO WIDE SLOT, FULLY INSERT. ATTENTION : POUR EVITER LES CHOCS ELECTRIQUES, INTRODUIRE LA LAME LA PLUS LARGE DE LA FICHE DANS LA BORNE CORRESPON- DANTE DE LA PRISE ET POUSSER JUSQU'AU FOND. Important Safety Instructions - All the safety and operating instructions should be read before the appliance is operated. - The safety and operating instructions should be retained for future reference. - All warnings on the appliance and in the operating instructions should be adhered to. - All operating and use instructions should be followed. 1. Water and Moisture - The appliance should not be used near water - for example, near a bathtub, washbowl, kitchen sink, laundry tub, in a wet basement, or near a swimming pool, and the like. 2. Carts and Stands - The appliance should be used only with a cart or stand that is recommended by th manufacturer. 3. An appliance and cart combination should be moved with care. Quick stops, excessive force, and uneven surfaces may cause the appliance and cart combination to overturn. 4. Wall or Ceiling Mounting - The appli- ance should be mounted to a wall or ceiling only as recommended by the manufacturer. 5. Ventilation - The appliance should be situated so that its location or position does not interfere with its proper ventilation. For example, the appliance should not be situated on a bed, sofa, rug, or similar surface that may block the ventilation openings; or, placed in a built-in installation, such as a bookcase or cabinet that may impede the flow of air through the ventilation openings. 6. Heat - The appliance should be situated away from heat sources such as radiators, heat registers, stoves, or other appliances (including amplifiers) that produce heat. 7. Power Sources - The appliance should be connected to a power supply only of the type described in the operating instructions or as marked on the appliance. 8. Grounding or Polarization - The precautions that should be taken so that the grounding or polarization means of an appliance is not defeated. 9. Power - Cord Protection - Power-supply cords should be routed so that they are not likely to be walked on or pinched by items placed upon or against them, paying particular attention to cords at plugs, convenience receptacles, and the point where they exit from the appliance. 10.Protective Attachment Plug - The appliance is equipped with an attachment plug having overload protection. This is a safety feature. See Instruction Manual for replacement or resetting of protective device. If replacement of the plug is required, be sure the service technician has used a replacement plug specified by the manufacturer that has the same overload protection as the original plug. 11.Cleaning - The appliance should be cleaned only as recommended by the manufacturer. 12.Power Lines - An outdoor antenna should be located away from power lines. SAFETY PRECAUTIONS CAUTION RISK OF ELECTRIC SHOCKS DO NOT OPEN PORTABLE CART Figure 2

13.Outdoor Antenna Grounding - If an outside antenna is

connected to the receiver be sure the antenna system is grounded so as to provide some protection against voltage surges and built-up static charges. Article 810 of the National Electrical Code, ANSI/NFPA 70, provides information with regard to proper grounding of the mast and supporting structure, grounding of the lead-in wire to an antenna-dis charge unit, size of grounding conductors,location of antenna- discharge unit, connection to grounding electrodes and requirements for the grounding electrode. See Figure 1. 14.Non-use Periods - The power cord of the appliance should be unplugged from the outlet when left unused for a long period of time. 15.Object and Liquid Entry - Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through openings. 16.Damage Requiring Service - The appliance should be serviced by qualified service personnel when: a) The power-supply cord or the plug has been damaged; or b) Objects have fallen, or liquid has been spilled into the appliance; or c) The appliance has been exposed to rain; or d) The appliance does not appear to operate normally or exhibits a marked change in performance; or e) The appliance has been dropped, or the enclosure damaged. 17.Servicing - The user should not attempt to service the appliance beyond that described in the operating instructions. All other servicing should be referred to qualified service personnel. ANTENNA DISCHARGE UNIT (NEC SECTION 810-20) ANTENNA LEAD IN WIRE POWER SERVICE GROUNDING ELECTRODE SYSTEM (NEC ART 250 PART H) GROUND CLAMP ELECTRIC SERVICE EQUIPMENT GROUNDING CONDUCTORS (NEC SECTION 810-21) GROUND CLAMPS EXAMPLE OF ANTENNA GROUNDING NEC - NATIONAL ELECTRICAL CODE

1. TUNER SECTION

TEST EQUIPMENT 1. Signal Generator with a frequency range of FM broadcast. 2. Oscilloscope with a side amplifier of approximately 100 KHz. 3. FM 75/50Ω dummy antenna. 4. VTVM FM ALIGNMENT 1. Turn on the FM signal generator and the VTVM allowing 15 minutes warming-up period. 2. Connect the VTVM across the headphone jack or speaker terminal. 3. Set signal generator frequency as listed in ALIGNMENT CHART and maintain a sufficient output level to provide an indication on VTVM. NOTE 1. Use a screwdriver with plastic or ceramic grip for all adjustments. 2. Standard test frequency 1 KHz and deviation 75 KHz for FM. - FM RF, IF ALIGNMENT CHART - Unless other specified set being switched FM mode, adjust generator's frequency to center of the FM band where no FM broadcast exists Otherwise adjustment of FM usable sensitivity, frequency range for FM band are not needed, but confirm these data are satisfied with specifi- cation. CAUTION : When realigning the FM receiving frequency the highest end of the frequency range should not be more than 108 MHz and the lowest end of the frequency range should not be less than 87.5 MHz, in order to comply with FTZ regulation in West Germany. 2. CD SECTION Note: 1. Use the oscilloscope with more than 10MΩ impedance. 2. Clean an object lens by an applicator with natural detergent when the signal level is lower than specified value with the following checks. RF LEVEL CHECK 1. Connect oscilloscope to test point TP502 and IC502 Pin66 on CD PCB. 2. Press power switch on. 3. Put test disc(TCD-781) in and press play button then pause button. 4. Confirm that oscilloscope waveform is clear. Clear RF signal waveform means that the shape"#"can be clearly distinguished at the center of waveform. 5. Adjust RV501 to get a clear waveform and maximum amplitude. Step Item Input Circuit Setup Output Circuit Setup Tuner Setting Adjust Point Adjustment 1 FM IF Adjustment Connect stereo signal generator to FM ANT terminal (J001) Connect DC voltme- ter to edge R201 FM98MHz75KHz Dev. 26dBµ L203 Adjust forDC 0V±0.1V 2 Auto Stop Sensitivity Connect stereo signal generator to FM ANT terminal (J001) Connect DC voltme- ter to edge of RV201 FM 98MHz 75KHz Dev. 26dBµ RV201 Adjust for DC 1.17V±0.02V Confirm stereo indica- tor is lighted and L/R channel is separated. SET FM Antenna Terminal(75 ohm) Carrier Frequency : 98MHz Output Level : 26dBuV Modulation:Audio 1kHZ, 75kHz Deviation FM RF SSG 75 ohm Coaxal Level : 1.2+0.3Vp-p RF Signal Waveform VOLT/DIV : 200mV TIME/DIV : 50ns

E-F BALANCE ADJUSTMENT

1. Connect oscilloscope to test point TP502 and TP503 on CD PCB. 2. Press power switch on. 3. Put test disc(TCD-781) in and press play button then pause button. 4. Pressing Fast Forward button, adjust RV502 to get that the oscilloscope waveform is symmetrical on the bottom in relation to 0V, and check this level. * Design and specifications may be subject to change without notice. 3. TAPE SECTION Test Tape be used HEAD ADJUSTMENT (AZIMUTH) 1. 10KHz test tape(example: MTT-114N) must be used for this adjustment. 2. Connect to VTVM or oscilloscope to the headphone jack or speaker terminal. 3. Press the play button. 4. Adjust the azimuth by using a screw driver to maintain the max. L&R output voltage. 5. Adjust tape A(1), tape B(2) respectively, Please secure the azimuth position by using locking paint. RECORDING BIAS OSCILLATOR FREQUENCY ADJUSTMENT 1. Connect the frequency counter to TP603, GND. 2. Press the REC button. 3. Adjust L603 to obtain 80 KHz±100Hz Tape Contents Use MTT-111N 3 KHz Tape Speed Adjustment MTT-114N 10 KHz Head Azimuth Adjustment MTT-5511 Blank Record Frequency Property Traverse Waveform A B 0V VTVM Scope R-CH L-CH 47 kohm 47 kohm Input Level Measurement Point Input Point Output Level Measurement Point

TAPE ALIGNMENT CHART

Step Item Reference Value Test Tape Adjust Point Test Point Note FIG. 1 Tape Speed Adjustment Normal 3,015~3,025Hz MTT-111N RV601 Line Out L/R Channel Confirm Wow & Flut- ter is within 0.35% FIG.1 3,000~3,010Hz MTT-111N RV601 Line Out L/R Channel Confirm Tape Speed of end position after adjustment at tape start position FIG.1 High 5,820~6,180Hz MTT-111N - - - - - - Shorted TP601, TP602 Confirm High speed after normal speed adjustment FIG.1 2 Azimuth Adjustment Maximum Level Phase:Within90° MTT-114N Head Screw Line Out L/R Channel FIG.2,3,4 3 Recording Bias Oscilla- tor Frequency Adjust- ment 80 KHz±0.5 MTT-5511 L603 TP603,GND Adjust with frequency counter connected. FIG.1 FIG. 1 : Tape Speed & Record Bias Oscillator Frequency Adjust Circuit Test Tape : MTT-111N(3kHz) MTT-5511(Blank) Frequency Counter Output Level Measurement Point Set FIG. 2 : Tape Azimuth Adjust Location (Record/Playback Head) FIG. 3 : Tape Azimuth Adjust Head Screw & Waveform FIG. 4 : Tape Azimuth Adjust Circuit & Waveform Forward Side Reverse Side Adjust with Frequency Counter Connected L-CH Peak R-CH Peak Screw Angle Output Level within 1 dB within 1 dB L-CH Peak R-CH Peak Screw Angle V H Oscilloscope L-CH Output Level Measurement Point Set Test Tape MTT-114N (10kHz) Screen Pattern In Phase 45 90 135 180 Good Wrong