PULSE/TONE TELEPHONE KIT MODEL AK-700/PT-323K Assembly and Instruction Manual
SECTION 1 - INTRODUCTION The Model AK-700 / PT-323K is a push button electronic telephone kit. Your telephone is equipped with the following features: A) a tone/pulse switch, B) automatic redial (for pulse dialer) of up to 32 digits, C) a ringer turn off switch, and D) four neon bulbs to give a visual indication that the telephone is ringing. The kit is built up in three sections: 1) Ringer, 2) Transmit-Receive, and 3) Dialer.
The Rotary Dial Telephone A simplified schematic diagram of the traditional rotary dial telephone is shown in Figure 3-2. The major parts of this telephone are explained below. Your kit is a newer electronic type telephone. When you build your telephone in Section 6, you will notice several differences between the traditional and electronic type telephones. Hook Switch When the hook switch is open (on hook) no current flows in the local loop.
Tone Dialer Tone dialing is accomplished with a keyboard of 12 keys arranged in 4 rows and 3 columns. As seen in Figure 3-4, low frequencies of 697, 770, 852 and 941 are associated with rows R1 through R4 and high frequencies of 1209, 1336 and 1477Hz are associated with columns C1 through C3. To send each digit, two frequencies are sent to the Central Office simultaneously. For this reason, this method of dialing is referred to as Dual Tone Multifrequency (DTMF).
Receiver There are several different types of receivers. In principle, they work the same as the speakers in your radio and TV. The speaker consists of a small coil attached to a diaphragm. The coil is mounted over a permanent magnet as shown in Figure 3-6. Coil current in one direction causes the coil and diaphragm to be repelled from the permanent magnet. Coil current in the other direction causes the coil and diaphragm to be attracted to the permanent.
SECTION 4 - PARTS LIST If any parts are missing or damaged, see instructor or bookstore. DO NOT contact your place of purchase as they will not be able to help you. Contact Elenco Electronics (address/phone/e-mail is at the back of this manual) for additional assistance, if needed. * BAG 1 * Resistors (For identifying values, refer to page 8). QTY 1 1 1 4 2 3 4 4 2 1 SYMBOL R18 R19 R7 R12, R13, R15, R20 R5, R23 R16, R17, R22 R1 - R4 R6, R9, R11, R21 R10, R14 R8 DESCRIPTION 10Ω 5% 1/4W 120Ω 5% 1/4W 2.
* BAG 4 * QTY 1 2 2 2 DESCRIPTION Switch SPDT (Hook) (S2) Switch SPDT (S1, S3) Screw 1/4” (Keyboard) Screw 5/8” (Case) PART # 541108 541109 642237 642477 * BAG 5 * QTY 1 1 1 1 1 1 DESCRIPTION Microphone (MIC) (without leads) Buzzer (B) Modular Jack Label Telephone # (2 parts) Microphone Pad Buzzer Pad PART # 568001 595223 621019 721006 780126 780125 * BAG 6 * QTY DESCRIPTION 1 Battery Snap 9V 1 Wire 22AWG Solid Yellow 6” * 1 Wire 26AWG Stranded Red 2” 1 Wire 26AWG Stranded Red 4” 4 Wire 26AWG Stranded
PARTS IDENTIFICATION BAG 1 Resistor BAG 2 Diodes Capacitors Epoxy Electrolytic Glass BAG 3 Transistor BAG 4 Integrated Circuit (IC) Resonator Disc Mylar IC Socket Switch SPDT (S1, S3) Switch SPDT (Hook) (S2) Neon Bulb 5/8” Screw Modular Jack BAG 5 Microphone Buzzer Microphone Pads Buzzer Pad 1/4” Screw BAG 6 Ribbon Cable Solder Wire Label & Cover Battery Snap BAG 7 Keypad PC Board Push Button Set (12) Contact Keypad MAIN BAG Main PC Board Speaker Pad Clear Top Case Clear Cradle
IDENTIFYING RESISTOR VALUES Use the following information as a guide in properly identifying the value of resistors. BAND 1 1st Digit Color Black Brown Red Orange Yellow Green Blue Violet Gray White Multiplier BAND 2 2nd Digit Digit 0 1 2 3 4 5 6 7 8 9 Color Black Brown Red Orange Yellow Green Blue Violet Gray White Resistance Tolerance Color Multiplier Black 1 Brown 10 Red 100 Orange 1,000 Yellow 10,000 Green 100,000 Blue 1,000,000 Silver 0.01 Gold 0.
CONSTRUCTION Introduction The most important factor in assembling your Tone/Pulse Telephone Kit is good soldering techniques. Using the proper soldering iron is of prime importance. A small pencil type soldering iron of 25 - 40 watts is recommended. The tip of the iron must be kept clean at all times and well tinned. Safety Procedures • Wear eye protection when soldering. • Locate soldering iron in an area where you do not have to go around it or reach over it. • Do not hold solder in your mouth.
SECTION 5 - EQUIPMENT NEEDED Tools Needed (not provided) Phillips Screwdriver (small point size) Long Nose Pliers Diagonal Cutters Small Pencil Type Soldering Iron of 25 - 40 Watts Note: The following equipment is not included unless indicated. Testing Equipment Needed: The test procedures are written for using AC and DC power supplies (only for final ringer test) or a 9V battery. If you don’t have a power supply for the ringer, transmit-receive and dialer tests, you can use a 9V battery.
PC BOARD ASSEMBLY Identify and install the following parts as shown in Figure 6-1. After soldering each part, place a check in the box provided. Figure A R3 - 47kΩ Resistor (yellow-violet-orange-gold) Mount the neon bulb as shown with the bulb in the same direction as marked on the PC board. Give about a 1/8” space between the bulb and the holes in the PC board.
Install the following parts. After soldering, place a check in the box provided. Identify the ringer switch as shown in Figure 6-2a. The ringer switch is mounted on the copper side of the PC board. Insert the switch tabs into the holes provided and solder the three terminals as shown in Figure 6-2b. Be sure that the switch is perpendicular to the PC board. To anchor the switch in place, grasp the switch tabs with your pliers and give a 1/8 turn as shown in Figure 6-2c.
If you have a 9VDC power supply, skip to the Ringer Test on page 14. RINGER TEST (Using a 9 Volt Battery) Test Equipment Needed • 9 volt battery (not provided). Use a fresh alkaline battery. • 9 volt battery snap. Testing is done with a 9 volt battery. To conserve the battery, it should be connected for only short periods of time and disconnected whenever tests are not actually being performed. Since capacitor C1 blocks the DC voltage, it is shorted for this test (Figure B on page 11). 1.
RINGER TEST (Using a Power Supply) Test Equipment Needed (not provided) • 9VDC power supply. Since capacitor C1 blocks the DC voltage, it is shorted for this test (Figure B on page 11). 1. Set the ringer switch to the OFF position (refer to Figure 6-2b). 2. Check to see which modular jack, type A or B, has been included in your kit. If you have type A, then use Figure 6-5a for testing. If you have type B, then use Figure 6-5b for testing. 3.
11. Unplug the telephone cord from the modular jack. 12. Peel the backing off of the buzzer side of the buzzer pad and place it on the buzzer as shown in Figure 6-6a. The pad goes directly on top of the three buzzer wires. Peel the second backing off of the buzzer mounting pad and stick the pad onto the solder side of the PC board as shown in Figure 6-6b. Note: When mounting, be sure that you allow room for the Pulse/Tone Switch and Hook Switch. 13. Continue to the Transmit-Receive Section.
PC BOARD ASSEMBLY Identify and install the following parts as shown in Figure 6-7. After soldering each part, place a check in the box provided. Q5 - 9014 Transistor (see Figure C) C6 - 1µF Lytic Capacitor (see Figure F) R19 - 120Ω Resistor (brown-red-brown-gold) R20 - 3.3kΩ Resistor (orange-orange-red-gold) R21 - 100kΩ Resistor (brown-black-yellow-gold) C4 - 47µF Lytic Capacitor (see Figure F) C9 - 47µF Lytic Capacitor (see Figure F) Q4 - 9013 Transistor (see Figure C) D8 - 2.
Install the following parts. After each step is completed, place a check mark in the box. Identify two wires (4” red and 3” gray), microphone and microphone pad. Cut the 4” red wire down to 2” and the 3” gray wire to 2”. Use the 2” red and 2” gray stranded wires and strip 1/8” of insulation off of each end. Identify the microphone. Bend the wires and very carefully solder the wires to the microphone as shown in Figure 6-8.
Identify the speaker with pad, 3” gray wire, and the second half of the 4” red wire (the first half was used for the microphone). Cut a 2” piece from the 3” gray wire and strip 1/8” of insulation off of both ends. Solder the red wire to the speaker + and the gray wire to the speaker – as shown in Figure 6-11. Solder the red wire to SP+ on the PC board and the gray wire to SP–. Figure 6-11 Red Wire + Gray Wire Speaker Pad If you have a 48VDC power supply, skip to the Transmit/Receive Test on page 19.
TRANSMIT - RECEIVE TESTS (Using a power supply) Before completing the assembly, we will want to power up and test the Transmit-Receive Section. See Figure 6-12 for these tests. B Green - Type A Red - Type B Telephone Cord A 48VDC Power Supply + Modular Jack Red - Type A Green - Type B C 1kΩ 5W Resistor Type A Green Figure 6-12 Type B Red Red Green CAUTION: This test and succeeding tests involve 48VDC. This voltage is potentially hazardous. Use great care when working with these voltages.
c) Check transistors Q2, Q3, Q4 and Q5. Be sure that they are the proper type and that the emitter, base and collector leads are in the correct holes as shown in the assembly instructions. d) Check that the resistors just installed are the correct values as shown in the assembly instructions. e) Check the components just installed for bad solder joints and solder bridges. f) Check the hook switch and wires to the PC board. 9. Turn the power supply OFF. Disconnect the voltmeter.
DIALER Circuit Description - The main elements of the Dialer Section are the keyboard and the dialer IC HM9102. These two components perform all of the functions of the rotary dial found in older telephones. The HM9102 is the tone/pulse switchable dialer with last number redial which is fabricated with CMOS technology. It has a wide operating voltage for both tone and pulse modes, and consumes very low memory retention current in the on-hook state.
PC BOARD ASSEMBLY Identify and install the following parts as shown in Figure 6-15. After soldering each part, place a check in the box provided. R13 - 3.3kΩ Resistor (orange-orange-red-gold) D5 - 1N4148 (see Figure E) R23 - 10kΩ Resistor (brown-black-orange-gold) R9 - 100kΩ Resistor (brown-black-yellow-gold) C8 - .02µF Discap (.02 or 203) R22 - 15kΩ Resistor (brown-green-orange-gold) C10 - 30pF Discap (30) X - Resonator 3.
KEYBOARD ASSEMBLY Insert the ribbon cable through the holes in the main PC board and solder as shown in Figure 6-16. Insert the ribbon cable through the holes in the keyboard PC board. Solder the ribbon cable to the keyboard’s PC board as shown in Figure 6-16. Carefully inspect the ribbon cable solder joints. If there are many solder bridges between adjacent pads, remove them with your soldering iron. If not already in place, snap the dial buttons onto the contact pad as shown in Figure 6-17.
If you have a 48VDC power supply, skip to the Dialer Test on page 25. DIALER TEST (Using a 9 volt battery) 1. Be sure that the telephone cord is connected to your modular jack. Be sure that the telephone is off the hook (hook switch not depressed). 2. Switch tone/pulse switch to the tone position. 3. Put the receiver to your ear and push the “1” button. You should hear a click. This is the result of the loop current being turned off and then back on. 4. Push the “2” button. You should hear a click. 5.
DIALER TEST (Using a power supply) 1. With the power supply OFF, reconnect the test circuit as shown in Figure 6-12. Position the PC board so that the hook switch is not depressed (off hook). 2. Set the voltmeter to read 48VDC. Turn the power supply ON and adjust it for 48VDC on the meter. 3. Switch tone/pulse switch to the tone position. 4. Put the receiver to your ear and push the “1” button. You should hear a click. This is the result of the loop current being turned off and then back on. 5.
FINAL ASSEMBLY See Figure 6-19. Place the PC board on the top case so that the ringer switch is in the ringer switch hole, the tone/pulse switch is in the tone/pulse hole and the two mounting holes on the PC board line up with the mounting posts on the top case. If the the PC board does not stay lined up with the two mounting posts, insert one or both of the 5/8” screws to keep it in place. Check the following: a) Be sure that the speaker wires do not lay between the speaker and the telephone top case.
FINAL TESTS (Using a 48VDC power supply) Test Equipment Needed (not provided): • • • • 48VDC power supply • Variac (only for ringer test) 1kΩ 5W resistor • Isolation transformer (only for ringer test) 48VDC voltmeter • Oscilloscope (only for voice test) 50VAC voltmeter (only for the ringer test) Perform the following tests and record the readings obtained in the space provided. DC TEST - Refer to Figure 6-20 for the DC test configuration. The oscilloscope is not used for the DC test. 1.
10. To measure the input voltage to the telephone, connect the positive voltmeter lead to the negative terminal of the power supply and the negative voltmeter lead to point C. The voltage reading should be between 5 and 12.5VDC. Input Voltage: _________________ 11. To measure the input current to the telephone, measure the current in the 1kΩ resistor. Connect the positive voltmeter lead to point “C” and the negative voltmeter lead to the negative power supply terminal.
2. Set the voltmeter to read 50VAC. Put the variac ON and adjust it to obtain 50VAC on the voltmeter. 3. Put the ringer switch ON. Plug in the telephone cord and position the telephone so that it is on hook (hook switch depressed). You should hear a steady ringing from the telephone. Variac Green - Type A Red - Type B Telephone Cord Isolation Transformer Telephone + Modular Jack Red - Type A Green - Type B 1kΩ 5W Resistor Type A Green Type B Red Red Green Figure 6-21 4. Take the variac OFF. 5.
SECTION 7 - INSTALLING THE TELEPHONE Mounting the Cradle Select a convenient place for your phone. Place the telephone cradle against the wall and mark the center of the upper lobes of the two mounting holes as shown in Figure 7-1. Screw in the two mounting screws (not provided) to about 1/4” of the mounting surface. Slide the cradle over the two screws and then tighten the screws. The phone and cradle are very light. However, if you are mounting the cradle on drywall, you should use drywall screws.
If present, connect the black and yellow wires in the same way. If these are missing, merely connect the black and yellow spade lugs to the “B” and “Y” screws. This will keep them from shorting to the other wires. Place the modular jack cover on the base. Plug in the telephone line cord. To locate the modular jack in the new location: Figure 7-3 Obtain the proper length of 4 wire telephone cable.
SCHEMATIC DIAGRAM -32-
QUIZ Mark the box next to the letter with the correct answer. Answers on next page. 1) The ringer in the traditional rotary dial telephone utilizes . . . A. a speaker and microphone. B. a permanent magnet and armature. C. a liquid crystal display. D. a piezoelectric buzzer. 2) The ringer circuits are connected . . . A. directly to the dialer IC. B. between the tip and ring outputs. C. to the speaker input. D. between the microphone and ground. 3) When the ringer switch is off, . . . A.
GLOSSARY DTMF Dual Tone Multifrequency. Electret Microphone A microphone made up of a capacitor with a dielectric that holds a permanent electric charge. FET Field Effect Transistor. Hook Switch A switch inside the telephone which closes when the receiver is lifted. IC Integrated Circuit. FCC Federal Communications Commission. Local Loop The pair of wires between a telephone set and the telephone company Central Office.
