Table 2-3. Troubleshooting-Continued
TEST OR INSPECTION
Adjust to 26 VDC.
Voltages and waveforms given in the diagrams are not abso-
lute and may vary slightly between units.
Step 2. 20 kHz Converter (P/O Main Frame) Check (fig. 2-4).
a. Connect 10:1 scope probe ground to C4 + C5 (-) bus; connect probe to collector of Q2. Adjust horizontal and vertical
positions, and trigger level of scope as required to observe display as shown in figure 2-5A.
Check Q1, Q2, Q3 and associated components. Check A2 PCB components (fig. 2-6). Replace defective
b. Leaving scope ground connected to - bus, connect scope probe to collector of Q5. Adjust scope as required to observe
display as shown in figure 2-5A.
Check Q4, Q5, Q6, and associated components. Check A2 PCB components (fig. 2-6). Replace defective
Step 3. Output Power Section (P/O Main Frame) Check.
a. Connect 1:1 scope probe ground to L3-1; connect scope probe to cathode (+) bus bar of CR8, CR9, and CR11. Adjust
scope as required to observe display as shown in figure 2-5B.
Turn OFF and disconnect all equipment. Using multimeter, check CR6, CR7, CR8, CR9, CR10 and CR11 (2 to 3
ohms in forward direction) secondaries of T1 and T2, L3, C14, and C15.
Replace defective component.
b. Using voltmeter, check for +5 ± 0.1 VDC between P1-A3 (+) and P1-A6 (ground) of rear panel.
Check CR12, CR13, CR14, CR15, CR20, CR21, and associated components. Replace defective component.