Klaas's magnetic deflection amplifier circuit
Posted: Tue Nov 28, 2017 1:00 pm
I have been working on klaas's magnetic deflection amplifier trying to fault find some problems i am having with it...
There is very little on the forum on the subject so putting it up here as a reference ...Klaas's procedure on how to test the circuit is something that should be kept .
BTW i have the original other circuit working but i am interested in using Klaas's circuit to learn about these things more than just copying a circuit and hoping for the best it works
1. - Disconnect the input signal to the 6k8 resistor,
- connect the deflection coil to the output
- power up the deflection amplifier.
- Multimeter: measure the voltage at the emitter op the first transistor 549,
- it should be - 0.6 volt.
- this is the voltage over the 1N4148 diode.
2. - Multimeter: measure the voltage at the base of the 549,
- it should be close to zero volts. Less than 0.1 volt.
3. - Multimeter: voltage at the collector of the 549,
- it should be about + 0.6 volt.
4. - Multimeter: voltage at the base of the 548: should be also + 0.6 volt.
5. - at the base of the 558 (PNP) should be - 0.6 volt.
6. - at the collector of the 548 (NPN) should be + 11.3 volts
7. - at the collector of the 558 (PNP) should be - 11.3 volts
8. - at the common collectors of the BD135-BD136 (or 137-138, or 139-140):
- should be close to zero, less than 1 volt.
9. - at the top of the 8.2 ohm: should be close to zero volts.
There is very little on the forum on the subject so putting it up here as a reference ...Klaas's procedure on how to test the circuit is something that should be kept .
BTW i have the original other circuit working but i am interested in using Klaas's circuit to learn about these things more than just copying a circuit and hoping for the best it works
1. - Disconnect the input signal to the 6k8 resistor,
- connect the deflection coil to the output
- power up the deflection amplifier.
- Multimeter: measure the voltage at the emitter op the first transistor 549,
- it should be - 0.6 volt.
- this is the voltage over the 1N4148 diode.
2. - Multimeter: measure the voltage at the base of the 549,
- it should be close to zero volts. Less than 0.1 volt.
3. - Multimeter: voltage at the collector of the 549,
- it should be about + 0.6 volt.
4. - Multimeter: voltage at the base of the 548: should be also + 0.6 volt.
5. - at the base of the 558 (PNP) should be - 0.6 volt.
6. - at the collector of the 548 (NPN) should be + 11.3 volts
7. - at the collector of the 558 (PNP) should be - 11.3 volts
8. - at the common collectors of the BD135-BD136 (or 137-138, or 139-140):
- should be close to zero, less than 1 volt.
9. - at the top of the 8.2 ohm: should be close to zero volts.