MALFUNCTIONS AND DEFECTIVE MODULES
Section I. ISOLATE MALFUNCTIONS TO MODULE LEVEL IN
Knowing the functions of the circuit will help you isolate the causes of malfunctions.
shown at TP2. Refer to figure 2-1.
(1) TP1 is the wave shape of the charge and discharge of the capacitor at the
inverting input of A2 resulting in the switching of the mv. TP1, charging time going positive
("on" time of the output transistor) and discharge time going negative ("off" time of the
output transistor) is varied by the front panel power level control knob. During the "on"
time, TP3 is high and Q4 output is saturated on.
(2) The current through the output transformer primary inductance increases
linearly by I = ET/L (current = voltage X time/inductance) and the energy stored at any time
is J = 1/2 LI2 (joule = 1/2 inductance X current squared). The power of P = 1/2 LI2 x Rate
of Storage and Discharge (power = 1/2 inductance X current squared X rate of storage
and discharge). When Q4 is turned off, the energy in T3 primary resonates with C13
producing a damped signal wave into an output load.
b. Circuit Description.
Functions of the level control and rate generator.
pulse width and rate is varied with the potentiometer R6 controlling the final power output.
(b) A2 is a self-starting mv. When the power is applied, pin 7 of A2 (the
collector output) is high and through CR1 and R6 charges C3 to pin 3 of A2 TP1.
(c) The non-inverting differential input pin 2 A2 is clamped to +10v
through CR3 to zener VR2.
(d) When pin 3 (voltage on C3) reaches +10v, the comparator changes
state, and pin 7 switches to low. Pin 2 is at the voltage division of R13 and R14 (3v). C3
discharges through CR2, R6, R8, and R7 until this voltage at pin 3 is lower than 3v and A2