This document is a service manual for the Sanyo TPM2770, a mini black and white television with an integrated AM/FM radio and a digital alarm clock.
Function Description
The Sanyo TPM2770 is a portable entertainment device combining a compact black and white television with a multi-band radio and a digital alarm clock. It is designed for versatile use, offering television reception for VHF and UHF channels, as well as AM and FM radio broadcasts. The integrated digital alarm clock provides timekeeping and alarm functions, allowing users to wake up to a buzzer, TV, or radio. The device supports multiple television systems, making it adaptable for use in various regions. Power can be supplied via an AC adaptor, a rechargeable battery pack, or a car adaptor cord, enhancing its portability.
Important Technical Specifications
Television System:
- "M" type: 525 lines/frame, 30 frames/sec, 60 fields/sec.
- "B, G, I" type: 625 lines/frame, 25 frames/sec, 50 fields/sec.
Frequency Range:
- VHF Channels: US system 2-13, EUR system 2-12
- UHF Channels: US system 14-83, EUR/UK system 21-69
- AM: 530-1,605 KHz
- FM: 88-108 MHz
Antenna Input Impedance: 75 ohm
Intermediate Frequency:
- TV Picture: 38.9 MHz
- TV Sound: 34.4 MHz (US) / 33.4 MHz (EUR) / 32.9 MHz (UK)
- Radio AM: 455 KHz
- Radio FM: 10.7 MHz
Picture Tube: 2.5-inch diagonal, 40 degrees deflection, C215P4 or E2239
Semiconductors:
- IC: 4
- Transistor: 26
- Diode: 32
Loudspeaker: 45 mm round type, 16 ohm
Sound Output: 150 mW (10% distortion) 200 mW Max.
Power Source:
- DC 9 V (AC adaptor 110-120/220-240 V, 50/60 Hz)
- Rechargeable battery pack (model NTP-500)
- 6 "AA" cells
- Car adaptor cord (optional)
Power Consumption: DC 2.5 W, AC 10 W (Adaptor)
Dimensions: 175 mm (W) x 62 mm (H) x 159 mm (D) approx. (without handle)
Weight: 0.96 Kg approx.
Usage Features
The TPM2770 offers a user-friendly interface with clearly labeled controls for various functions.
Television Operation:
- Telescopic Antenna: Used for receiving TV (VHF, UHF) and FM broadcasts.
- TV System Switch: Allows selection of the desired television system.
- TV Select Switch: Sets the desired channel band.
- Tuning Knob (TV): Tunes to the desired channel for vivid picture and clear sound.
- Vertical Hold Control (V-HOLD): Adjusts to stop up or down movement of the picture.
- Brightness Control (BRIGHT): Adjusts picture brilliance.
- Contrast Control (CONTRAST): Adjusts black and white elements of the picture.
Radio Operation:
- Radio Tuning Knob: Tunes to the desired AM or FM station.
- TV-Radio Select Switch: Selects between TV and Radio (AM or FM) functions.
Digital Alarm Clock:
- Light Button (LIGHT): Illuminates the LCD clock display.
- Time Set Button (TIME SET): Used for setting the clock.
- Hour Set Button (HOUR): Adjusts the hour.
- Minute Set Button (MINUTE): Adjusts the minute.
- Timer Select Switch (TIMER SELECT): Sets the alarm to wake up with a buzzer, TV, or radio.
General Features:
- Main Switch: Turns the power ON or OFF, or activates the Timer function. It also has an "OFF (charge)" position for recharging the optional battery pack when the AC adaptor is plugged in.
- Volume Control (VOLUME): Adjusts the audio output.
- Earphone Jack (EAR): For private listening, an earphone (supplied) can be plugged in.
- External Power Jack (DC IN 9V): For connecting the AC adaptor or car battery cord.
- Battery Compartment: Houses dry cells or the optional rechargeable battery pack.
Maintenance Features
The service manual provides detailed instructions for disassembly, component handling, and alignment procedures, crucial for maintenance and repair.
Mechanical Disassemblies:
- Cabinet Top Removal: Involves removing screws, opening the battery compartment lid, and taking out the radio tuning knob. Caution is advised regarding the rod antenna, handle, and speaker lead socket.
- Radio P.C.B. Removal: Requires removing the cabinet top, two screws, and lifting the board, potentially disconnecting sockets and leads.
- TV P.C.B. Removal: Involves removing the cabinet top and radio P.C.B., taking out four knobs (TV SELECT, TV-RADIO SELECT, ON-OFF SELECT, VOLUME), removing two screws, and carefully detaching the cabinet bottom and front cabinet. Caution is advised to avoid excessive force on Contrast, Brightness, and Vertical Hold knobs.
- Picture Tube Removal: Requires removing the cabinet top, radio P.C.B., and cabinet front, then detaching the anode cap and picture tube socket, loosening the deflection yoke screw, and pulling the picture tube.
- Reassembly Caution: Leads must be dressed away from SF101 and T101, and the 7P socket lead away from the rod antenna lead.
Radio Dial Calibration:
- Involves turning the tuning capacitor drum and dial shaft counterclockwise until they stop, aligning the drum and shaft, and then placing the tuning belt on the drums.
Handling Chips:
- Tools: Use a pencil-tip soldering iron (less than 30W, tip less than 3mm diameter) with temperature control, 0.7-1.0mm solder, braided wire, tweezers, and needle-nose pliers.
- Soldering Temperature: 270 ± 10°C (518 ± 18°F) for resistors/capacitors, 250 ± 10°C (482 ± 18°F) for transistors.
- Soldering Time: Complete work in less than 3 seconds to prevent damage.
- Orientation: Resistor chips should have the black front surface facing upward. Capacitor chips can be placed without regard to side.
- Re-usage: Removed chip parts should not be re-used due to potential damage from heat during removal.
Removal of Chip Elements:
- Apply heat and absorb melting solder with braided wire.
- Hold the chip with tweezers and gently turn while applying heat to unsoldering it.
- Clean the circuit board base of any remaining solder.
Mounting Chip Elements:
- Place the chip correctly on the pattern and solder it, ensuring the soldering iron does not touch the chip body.
- Allow the chip to cool after soldering.
Handling and Repairing of LCD Quartz Clock P.C.B.:
- Static Electricity: LCD Quartz Clock uses C-MOS LSI and ICs, which are sensitive to static electricity. Proper protection is required when handling.
- Environmental Protection: Do not expose the LCD to direct sunlight or extremely hot temperatures, as it is weak against ultraviolet rays.
- Physical Handling: Avoid strong shocks to the LCD surface, which can cause defective electrical contacts or time display issues. The polarized plate is easily scratched, so handle with care.
- Cleaning: After attaching the LCD to the unit, wipe its surface with a soft cloth to prevent electrification.
- P.C.B. Handling: Do not touch the P.C.B. pattern directly; hold both ends.
- Soldering: Use a soldering iron for ICs with insulation resistance of 300M-ohm, or ground the ordinary soldering iron to prevent alternate current leakage. Wear a grounded conductive bracelet with a 1M-ohm resistor during repair.
- Grounding: Ground the meter body to avoid electrification. Do not use the resistance range at the measurement by the tester.
- Battery Removal: Before removing the LCD Quartz Clock P.C.B., take out the six dry batteries and silver oxide battery.
- Discharging: Discharge electric potential by shorting the +B and -B lines in the Clock Control Unit, then ground the +B line.
- Storage: Store the watch in an ambient temperature of 0-50°C and low humidity, in a dark place. Do not unwrap parts before use.
- Repair Parts: Completed LCD Quartz Clock P.C.B. and LCD Quartz Clock Control Unit are prepared as repair parts.
- Work Surface: Spread a conductive sheet on the worktable and ground it for repair.
- Troubleshooting: Check silver oxide battery installation and lead connections. Replace the complete LCD Quartz Clock P.C.B. or LCD Quartz Control Unit if the display does not appear, is missing parts of the digital display, or skips time.
Television Adjustment:
- Safety Precautions: Do not discharge, arc, or measure high voltage when the CRT high voltage lead is connected. Discharge the 2nd anode of the CRT only after the high voltage lead has been disconnected. Disconnect all power before repairs. Do not short any portion of the circuit when power is on.
- Picture Focus: Connect the white lead from Point C9 on the CRT Socket P.C.B. to one of three terminals (F0, F1, F2) for best focus.
- Deflection Yoke and Centering Rings: Turn on the receiver, disconnect the antenna, loosen the deflection yoke clamp, move the yoke forward, rotate it for straight raster edges, and tighten the clamp. Center the raster and eliminate shaded corners by rotating the centering rings.
- Vertical Height: Adjust V-Height control (VR502) for proper picture height. Rotate V-Hold control (VR501) clockwise or counterclockwise to confirm picture rolls up or down at extreme positions.
- Horizontal Hold Control: Adjust H-Hold control (VR601) to correct any slanting of the picture.
- Sound IF Alignment: Tune to a strong local station, reduce signal strength until distortion appears, then adjust T301 (CCIR-I, CCIR-B/G, or CCIR-M) for maximum sound without buzz and distortion.
- AGC Adjustment: Connect a 65 dB 75 ohm open end signal to the VHF antenna terminal and adjust AGC DELAY Control (VR101) to 2.2±0.05 V at the AGC Terminal of the Tuner.
- Sub Tuning Adjustment: When adjusting the channel indicator at each TV band, set the tuning knob to the highest channel. Tune to a strong local station, reduce signal strength until distortion appears, then set Sub Tuning Controls (V-Low: VR002, V-High: VR003, UHF: VR004) for best picture and minimum sound beat.
AM Radio Alignment Procedure:
- Measuring Instruments: Connect a test oscillator, VTVM or tester, and oscilloscope.
- Preliminaries: Set oscilloscope to prevent waveform saturation, VTVM to 3V AC range, and modulate test oscillator at 1KHz with approximately 30% modulation.
- AM IF Adjustment (455KHz): Set test oscillator to 455KHz, adjust cores of IFT, RT04, and RT05 for maximum VTVM reading, keeping output low and checking for waveform saturation.
- AM Tracking Adjustment: Remove paraffin from the bar antenna coil (RL04), set test oscillator and radio dial to 600KHz, move the bar antenna coil for maximum oscilloscope waveform and VTVM indication, then fasten with paraffin. Set test oscillator and radio dial to 1400KHz, adjust trimmer capacitor (VCT-A) for maximum oscilloscope waveform and VTVM indication. Repeat adjustments two or three times.
- AM Frequency Range Adjustment (505KHz - 1650KHz): Set test oscillator to 505KHz, turn radio tuning knob to lower frequency (capacitor plates fully meshed), adjust RT03 core for maximum oscilloscope waveform and VTVM indication. Set test oscillator to 1650KHz, turn radio tuning knob to highest frequency (capacitor plates fully open), adjust trimmer capacitor (VCT-0) for maximum oscilloscope waveform and VTVM indication.
FM Radio Alignment Procedure:
- Measuring Instruments: Connect a test oscillator, VTVM or tester, and oscilloscope.
- Preliminaries: Set VTVM to 3V AC range. Make a link coil (diameter 3-5cm) for test oscillator output and set it on RL02 for FM IF adjustments. Connect oscillator output to FM antenna terminals for other adjustments.
- FM IF Adjustment (10.7MHz): Set link coil on RL02, set test oscillator to 10.7MHz, and adjust IFT RT02 for maximum VTVM reading. Minimize test oscillator output and adjust IFT RT01 and RT02 for maximum VTVM reading. Repeat adjustments two or three times.
- FM Tracking Adjustment: Set test oscillator to 90.0MHz and connect output to FM antenna terminals. Set radio dial to 90.0MHz and adjust RL01 for maximum, then secure with paraffin. Set test oscillator and radio dial to 105.0MHz, adjust trimmer capacitor (VCT-FC2) for maximum amplitude on oscilloscope and VTVM indication. Repeat adjustments two or three times.
- FM Frequency Range Adjustment (87.2MHz - 109MHz): Set test oscillator to 87.2MHz and connect to FM antenna terminals. Turn radio tuning knob to lower frequency (capacitor plates fully meshed), adjust RL03 for maximum indication on oscilloscope and VTVM, then secure with paraffin. Set test oscillator to 109.0MHz, turn radio tuning knob to highest frequency (capacitor plates fully open), adjust trimmer capacitor (VCT-FC1) for maximum indication on oscilloscope and VTVM.
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