The Sencore TF26 Touch Tone Cricket service manual provides detailed instructions for setting up and operating the device, which tests transistors and FETs without requiring knowledge of their basing or polarity. It also includes troubleshooting guidance, recommending retesting transistors out of circuit if they initially test as bad in-circuit, and checking for issues like shorted foils or incorrect resistor values if problems persist.
Manual Overview
The Sencore TF26 Touch Tone Cricket service manual provides detailed guidance on operating and servicing the device, focusing on troubleshooting, error diagnostics, calibration, and board-level instructions. The TF26 is designed to test transistors and FETs without requiring prior knowledge of their basing or polarity. It uses a computer logic circuit to determine if a device will invert a square wave input, with six pushbuttons and a polarity switch facilitating all possible connection combinations. For troubleshooting, if the device does not chirp during a gain test, it is likely faulty. The manual advises retesting any transistor that tests bad in-circuit by removing it for an out-of-circuit test to confirm the diagnosis. Calibration involves static and electrical meter zeroing and leakage calibration. Board-level guidance includes disassembly instructions and meter and speaker replacement. The manual emphasizes safety precautions, such as discharging capacitors and using insulated floors to prevent shock.
Quick Issues Covered
- Diagnose transistor issues with gain and leakage tests.
- Calibrate static and electrical meter zero for accurate readings.
- Use schematics for tracing shorted foils on circuit boards.
Overview
The TF26 Touch Tone Cricket is a transistor and FET tester that simplifies the testing process by eliminating the need for technical knowledge of basing diagrams or polarity. It uses a computer logic circuit to determine the condition of the device under test, providing an audio “chirp” and visual indication for good devices. The manual covers safety reminders, features, specifications, controls, connections, operation procedures for gain and leakage tests, circuit description, disassembly instructions, calibration, troubleshooting, and service information.
Specifications
- TYPE DEVICES TESTED: Diodes, transistors, and single gate FET’s.
- TEST VOLTAGES:
- GAIN TEST: Vcr – Plus or minus 5V
- VBE – 3 volts peak to peak, centered on zero reference.
- LEAKAGE TEST: Vcp – 5 volts
- TEST CURRENTS FOR GAIN TEST: Ic -10mA max. 2 – 3mA average continuous Ig – 7mA max. 3mA average continuous.
- SEMICONDUCTOR COMPLIMENT: 7 – 1N4148; 2 – 2N5172; 1 – 2N4248; 1 – 10 volt zener; 1 – LM3900 Quad op-amp;1 – SN7400 Quad NAND gate.
- METER LIGHT: 1-No. 47 Pilot Lamp
- SIZE: Height: 10” (25.4cm) Weight: 4 lbs. (1.8Kg) Width: 5 1/2”(13.8cm) Depth: 3 1/2” (8.9cm)
Controls & Indicators
The front-panel controls/indicators for the TF26 include a polarity switch, a function switch, and six pushbutton test switches. The polarity switch selects the test voltage polarity for the device under test, with options for NPN or PNP transistors and N channel or P channel FETs. The function switch allows selection between gain and leakage tests. The six pushbutton switches are used to apply the test voltage to the device’s elements.
Installation / Setup
Refer to the PDF for details.
Operation
The TF26 Touch Tone Cricket is designed to test transistors or FETs without needing to know their basing, polarity, or type. The device uses a computer logic circuit to determine if the transistor or FET will invert a square wave input. It features six pushbuttons and a polarity switch to provide all possible combinations of connections. To perform a gain test, the user should:
1. Remove power from the equipment containing the device being tested and discharge all power supply filter capacitors.
2. Turn on the TF26 and connect the test leads to the device’s leads. The basing of the transistor does not need to be determined as the touch tone circuit will handle it. If the device is a plug-in, the front panel mounted transistor socket can be used.
3. Select the GAIN test and press each of the six test buttons in turn. If the Cricket does not chirp and indicate in the good area of the meter, select the opposite polarity and press the test buttons again. If the Cricket still doesn’t chirp, the device is probably bad. It is advisable to retest the “bad” transistor after removing it from the circuit to isolate rare instances where a good transistor tests bad in-circuit.
In some cases, a good transistor may test bad in-circuit, particularly if the circuit’s base to collector resistance is less than 100 ohms or if large electrolytic capacitors are connected directly between the base or collector leads and ground. If a transistor tests bad in-circuit and good out-of-circuit, it may indicate other circuit problems, such as shorted foils on the board or large resistors connected to the transistor that have changed value or become shorted.
Troubleshooting & Error Codes
Refer to the PDF for details.
Safety & Warnings
When testing electronic equipment, there is always a danger present. Unexpected high voltages can be present at unusual locations in defective equipment. The technician should become familiar with the device that he is working on and observe the following precautions:
1. When making test lead connections to high voltage points, remove the power. If this cannot be done, be sure to avoid contact with other equipment or metal objects. Place one hand in your pocket, as a safety precaution and stand on an insulated floor to reduce the possibility of shock.
2. Discharge filter capacitors before connecting test leads to them. Capacitors can store a charge that could be dangerous to the technician.
3. Be sure your equipment is in good order. Broken or frayed test leads can be extremely dangerous and can expose the technician to dangerous potentials.
4. Remove the test leads immediately after the test has been completed to reduce the possibility of shock.
5. Do not work alone when working on hazardous circuits. Always have another person close by in case of accident. Remember, even a minor shock can be the cause of a more serious accident, such as falling against the equipment, or coming in contact with high voltages.
Download 2 Service manual (PDF – 1.6 MB)
Sencore TF26 Touch-Tone Cricket Operation Service Manual: Troubleshoot and calibrate model 2 efficiently. File size: 1.6 MB.
- Brand: Sencore-tf26-touch-tone-cricket-operation-service-manual
- Model: 2
- Type: Service manual
- File size: 1.6 MB
Overview
Brief overview of the product.
Specifications
- Key spec 1
- Key spec 2
Controls & Indicators
Control panel/button layout.
Installation / Setup
- Step 1…
- Step 2…
Operation
Basic usage, modes, cycles.
Troubleshooting & Error Codes
| Issue / Code | Fix |
|---|---|
| Example | How to fix… |
Safety & Warnings
- Important warning…
Downloads
Download 2 service manual (PDF)
Sencore TF26 Touch Tone Cricket Operation & Service Manual Overview
The Sencore TF26 Touch Tone Cricket is a specialized test instrument designed for telecommunications technicians to generate and analyze touch-tone signals. This device is essential for testing and troubleshooting telephone lines, ensuring proper signal transmission and reception in analog telephony systems. The manual provides detailed instructions for operation, service, and maintenance of the TF26, helping users maximize the device's performance and longevity.
Main Features and Specifications
- Generates standard touch-tone (DTMF) signals for telephone line testing
- Compact and portable design suitable for field and lab use
- Clear, easy-to-read interface with labeled keypad for tone generation
- Accurate frequency output conforming to telephony standards
- Battery-powered operation with long-lasting battery life
- Durable casing for reliable use in various environments
- Includes service and calibration procedures in the manual
Basic Usage and Operation Tips
To operate the TF26 Touch Tone Cricket, power on the device and select the desired touch-tone digits using the keypad. Connect the device to the telephone line or test circuit as instructed in the manual. Use the generated tones to verify line integrity, signal clarity, and proper switching functions. Always ensure the device is properly calibrated before use to maintain accuracy. Store the unit in a dry, dust-free environment when not in use.
Troubleshooting and Maintenance Notes
If the device fails to generate tones or produces distorted signals, check the battery level and replace if necessary. Inspect all connectors and cables for damage or loose connections. Refer to the service manual section for detailed calibration steps and component replacement procedures. Regularly clean the keypad and casing with a soft, dry cloth to prevent dust buildup. Avoid exposure to extreme temperatures or moisture to maintain device reliability.
Safety Reminder
Always disconnect the TF26 Touch Tone Cricket from telephone lines before opening the device for service or battery replacement. Use caution when working with live telephone circuits to avoid electrical shock. Follow all safety guidelines outlined in the manual to ensure safe and effective operation.