TESTING THREE TRANSISTOR RADIO COMPONENTS

TESTING THREE TRANSISTOR RADIO COMPONENTS

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TESTING THREE TRANSISTOR RADIO COMPONENTS

A. Testing of Fixed Resistors
B. Testing of Paper, Mica, and Cramp capacitors
C. Testing of Electrolytic Condensers
D. Testing Diodes
E. Testing of Non-Fixed Resistors
F. T...

TESTING THREE TRANSISTOR RADIO COMPONENTS

A. Testing of Fixed Resistors
B. Testing of Paper, Mica, and Cramp capacitors
C. Testing of Electrolytic Condensers
D. Testing Diodes
E. Testing of Non-Fixed Resistors
F. Testing Transformer (Transformer)
G. Transistor Testing
H. Testing Spool Antenna I Testing Varco (Variable Conderis- or)
J. Loudspeaker Testing

Before the transistor radio to be repaired is disassembled and examined further, do the testing or testing as listed below.
1. Check the connecting cables, maybe there are not connected or broken.
2. Check the connection between radio and LS.
3. Check the connection with the power source.
4. After all is well, turn on the radio. If a wheezing sound is heard from the speaker, the current source and final amplifier are good.
5. If you don't hear any sound, turn off the radio. Disconnect the current source and test each component in reverse order (loudspeaker - amplifier - input section).

testing three transistor radio components

A. TESTING FIXED RESISTORS
The things that need to be considered in testing a fixed resistor are as follows.
1. Calculate the resistor value with a color code.
2. When testing, try not to touch one of the resistor legs because it will affect the test results or measurements.
3. If the value of the resistor is fixed between 0 to 500 Q then an ohmmeter on the X1 scale is used and for values ​​of 500 ohms and above, the KQ scale is used
4. Look at Figure 3.1 below!

fixed resistor testing

The conditions for testing with an ohmmeter are as follows.
1. If the moving needle shows a value that corresponds to the value calculated with the color code and the tolerance limit given, the resistor is in good condition.
2. If the needle moves smaller than the calculated color-coded value the resistor is broken.
3. If the appropriate ohmmeter scale turns out the needle is stationary (needle position is zero to the left) then the resistor breaks.
4. If the needle moves to show zero (on the right) then the resistor is shorted (short circuit).

 

PAPER, MICA, AND CERAMIC CONDENSATOR TESTING,

These capacitors do not have positive and negative polarity. The test method is as follows.
1. Use an ohmmeter, choose the highest measurement limit.
2. Connect the two ends of the plug on the two legs of the capacitor to be checked.

testing of ceramic capacitors

3. Pay attention to the needle pointer when you connect the measuring cable.
a) If the needle moves a little and then comes back, it means the condenser is good.
b) If the needle moves to show a certain number and does not return or shows zero, it means that the condenser is in a leaky state.

The larger the capacitor capacity, the greater the needle deviation. For a capacitor whose value is less than 1000 pF, the needle drift is almost immobile.

ELECTROLITE CONDENSATOR TESTING
How to test the electrolyte capacitor is as follows.
1. Using an ohmmeter, point the selector switch at position x10.
2. Connect the red wire (probe) to the negative capacitor foot

electrolytic capacitor testing

then the result:
a) if the ohmmeter needle moves to the right and then returns to its original point, it means that the capacitor is in good condition;
b) if the needle moves to the right and does not return to its original point, it means the capacitor is leaking (short circuit);
c) if the needle does not move at all, it means the condenser is in a broken state.


Diode testing is done using an ohmmeter. The diode test steps are as follows.
1. Move the selector switch to position x10.
2. The red wire and the black wire are connected by cathode and anode, respectively. The test results are:
a) if the needle is moving, the diode is good;
b) if the dial is not moving, the diode has broken;
c) if the needle shows zero, it means the diode is shorted.
3. The red wire and the black wire ohmmeter are connected to the anode and cathode, respectively. The result is:
a) if the needle moves slightly or is stationary, the diode is good;
b) if the needle moves far away or reaches zero, the diode is shorted or leaking.

how to test a diode

FIXED RESISTOR TESTING
On a variable resistor or potentiometer with a switch, there are legs a, b, c, d and c. The b feet are the sliding contact feet, while the d and c legs are switches. Potentiometer testing see Figure 3.5 below!

potentiometer testing

Testing the potentiometer with a switch and the possible results are as follows.
1. If at the time of testing legs a and feet c.
a) the needle shows a number that corresponds to the potentiometer value printed on its body, so the potentiometer is in good condition;
b) if the needle shows a number greater or less than the stated value, the value has changed.

2. At the time of testing, the feet a and b or feet c and b and the resistor feet were rotated.
a) if the needle moves according to the rotation of the sliding contact handle then the resistor is in good condition;
b) if the needle movement does not match the rotation of the resistor shaft then the contact of the resistor motion is worn or rough.

3. Testing on legs d and e, namely checking the merits of the switch.
a) The switch is in the on position (connected):
1) if the needle moves then the switch is good;
2) if the needle is stationary then the switch breaks.

b) Switch in the off position (separate):
1) if the needle is stationary then the switch is good;
2) if the needle moves, the switch occurs short circuit (correction).

TRANSFORMER TESTING (TRAFO)
Testing of this transformer component consists of the base:
1. testing between primary coils;
2. testing of the primary coil and secondary coil;
3. testing the transformer housing.

The output transformer consists of:
1. the primary coil (each leg a, b, and c), the secondary coil (each leg d and e);
2. core or core of transformer body.

How to test the output transformer can be seen in Figure 3.6 and Table 3.1 below.

testing on a transformer

TRANSISTOR TESTING,
Transistor Testing Method 1
Transistor testing is a test to determine whether the state of the transistor is good or bad. Transistor testing must know the type of transistor to be tested for NPN or PNP. To find out the type of transistor is done in two ways as follows.
a. Use an ohmmeter with a selector switch on the x10.
b. Measure the resistance E - B and K - B (B is connected with a red wire while E and K are connected with a black wire. (See Figure 3.7) In an NPN transitor, the pointing of the needle must be a low value whereas in a PNP transistor, the needle has to be a high value.
c. Measure the resistance B - E (opposite E - B) and B - K (inverse K - B), see Figure 3.8, for NPN transitor the needle designation must be low.

transformer testing

pnp transistor

Transistor Testing Method II
Look carefully at the image below!

npn transistor

The steps for testing the way II transistors are as follows.
a. Designate either the ohmmeter wire as a guide, the red wire or the black wire. For example, we define the red wire as the guideline cable.
b. Connect the red wire as a guide wire with one of the transistor legs, legs a, b, or c. Then, alternately connect the black wire with the other leg until you get the same measurement result, that is, all the needles are stationary or moving.
c. If the measurement results are not the same, that is, one needle moves and the other is stationary, then move the position of the guide wire and the selected transistor leg to the other leg until you get the same results.


testing way ii transistors

d. By replacing the red wire as the guide wire, the type of transistor can be found from the same measurement results, namely:
1) all needles move: PNP type transistor;
2) all needles are silent: an NPN type transistor.
e. By using the black wire as the guide wire, the type of transistor tested can be found from the same measurement results, namely:
1) all needles move: NPN type transistor;
2) all needles are silent: PNP type transistor.


npn transistor testing

pnp transistor testing

f. The leg connected by the guide wire, either the red wire or the black wire, is the base leg (B). With this knowledge, it can make it easier to test transistors for both NPN and PNP types as in Figure 3.12 and Table 3.2 below!

transistor testing

transistor test results provisions

how to test the antenna spool

Testing the antenna spool is testing the relationship between the antenna legs.
1. Testing leg a and leg b, if: • the needle moves, the antenna spool is in good condition;
• the needle is still, the antenna spool is broken. 2. Testing legs a, b, with feet c or d, if:
• the needle moves, the antenna spool is short-circuited; • the needle is stationary, the antenna spool is in good condition.

VARCO TESTING (VARIABLE CONDENSATOR 1
The varco test is the process of testing whether there is a connection between the rotor plate (the moving varco part) and the stator plate (the still varco part), or between the a (rotor) and b (stator) leg. Look at Figure 3.14 below!

varco check


Test result provisions.
1. If the needle moves, it means that the varco is short connected, because the two rotor and stator plates, which should be separate, are connected to each other.
2. If the clock is silent, the varco is good.

LOUDSPEAKER TESTING
Testing the loudspeaker is testing or testing the voice wire coil in it. The test method is as follows.
1. Use the ohmmeter, selector switch at position x10.
2. Connect the two plug cables to the two loudspeaker terminals.
3. Read the needle on the scale board, if the needle moves to show a certain number, it means that the loudspeaker is good.
4. If the needle shows zero, it means that there is a short circuit in the coil.
5. If the needle does not move, it means that the coil has broken.

loudspeaker check

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