Service Manual for Toshiba 21N21E2 Colour Television

Important Information from the Manual

This document is a professional service manual intended for qualified technicians. It contains critical safety notices, electrical adjustment procedures, and mechanical disassembly instructions for the Toshiba 21N21E2 colour television. Always observe safety precautions regarding high voltage and X-ray protection when servicing this unit.

Safety Notices

• High Voltage: The unit contains high voltage parts. Always discharge the anode cap potential voltage before starting work.
• X-Ray Safety: Safety is secured against X-rays by the cathode-ray tube and high voltage peripheral circuits. Use designated parts and do not modify these circuits.
• Insulation Check: After servicing, confirm insulation resistance between the AC cord plug blades and external metal (antenna terminal/earphone jack) is greater than 1M ohm using a 500V insulation resistance meter.

Disassembly Instructions

Removal of Anode Cap

1. Connect an alligator clip to a flat-blade screwdriver and ground.
2. While holding the plastic part of the screwdriver, touch the anode support with the tip to discharge voltage.
3. Flip up the rubber cap sides and remove the support.

Removal and Installation of Flat Package IC

• Use masking tape to protect surrounding parts.
• Heat leads with a blower-type IC desoldering machine.
• Use tweezers to remove the IC once leads are desoldered.
• Use braided shield wire to absorb excess solder.
• When installing, ensure correct polarity and solder diagonal leads temporarily before soldering all pins.

Service Mode

To enter Service Mode, press both the set key and the remote control key for more than 2 seconds. Available modes include:

• 0: Reset user settings (Picture, Volume, Language).
• 1: Factory initialization (resets channel settings and power-on hours).
• 6: Display power-on total hours.
• 8: Write EEPROM initial data.
• 9: Display Adjustment Menu.

Electrical Adjustments

The manual provides detailed procedures for:

• Constant Voltage: Adjust VR501 to 117V ± 1.0V.
• VCO and AGC: Specific oscillator frequencies and voltage targets are provided for tuning.
• Focus: Adjust focus volume until the picture is distinct.
• White Balance: Adjust R Drive, G Drive, and Cutoff settings.
• Purity and Convergence: Procedures for static and dynamic convergence using magnets and deflection yoke adjustments.

Parts Ordering

When ordering parts, provide the Model Number (found on the back of the product) and the Version Letter (found at the end of the serial number), along with the Part Number and Description from this manual.