Use the following troubleshooting techniques to identify the causes of malfunctions.
a. Equipment. You need the following equipment to troubleshoot the hyfrecator:
Electrosurgical test set.
b. Troubleshooting Guideline. Refer to the Hyfrecator Troubleshooting
Guideline in the appendix. Use it to isolate malfunctions. The guideline consists of three
Symptom. Lists symptom you are observing with the malfunctioning unit.
(2) Probable Cause. Indicates, in priority order, the most likely causes for the
symptom under discussion.
(3) Corrective Action. Lists the proper corrective action to take to repair the
malfunction for the probable cause indicated.
c. Troubleshooting a Malfunctioning Printed Circuit Board . Refer to the Hyfrecator
Troubleshooting Guideline in the appendix, Symptom number six.
Remove the active Q4 devices.
Measure for voltage integrity.
Check test points TP1 through TP3 for correct operation. Refer to
Insert the output transistor for operation and final calibration.
(2) Critically inspect test point TP4 for a heavily damped sinusoid. This
damping occurs whether the output is loaded or open circuited. With a dial setting of half
scale, and the output loaded, the first sinusoid completed is about 400v peak. The second
sinusoid is about 100v peak. With an unloaded output, the damping of the wave shape
goes virtually to zero volts in 5 cycles.
(3) If the above conditions are not met on full power output (30w bipolar),
check transistors Q5, Q4, and Q3 in that order for a possible shorted condition. Check
CR9 and CR14 if needed.