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Troubleshooting AC-Turn-On Circuits
Relay AlK1 closes at 2.5 seconds and AC FAULT goes high at 2.9 seconds after 21V UNREG reaches about 13Vdc.
ACFAULT high enables the PWM if OVERVOLTAGE, INHIBIT, and OVERTEMP are also high.
Circuits Included. High AC and AC Dropout Detectors, Bias Voltage Detector, Q11A, 3-Second Delay and Relay Driver--
all on A2 control board.
Setup. The Main Troubleshooting Setup, Page 53. Apply the ac mains voltage to the isolation transformer, and set the
external supply to 0Vdc.
Inputs:
NODE (+) * SETUP MEASUREMENT SOURCE
A2J7-24 5.0Vdc A209 (emit.)
A2J7-22 ≈ 21Vdc A1CR2,A1CR5
A2Q11-16 f.w.rect,0.8V pk A1CR3,A1CR4
A2U20-13 TTL sq wave,20KHz A2U20-6
Outputs:
NODE (+) * SETUP MEASUREMENT
A2U17-9 cycle power ≈ 13.5Vdc
A2U17-14 cycle power ≈ 1.4Vdc
A2Q11-14 cycle power transition 0 to 5Vdc at 25 sec
A2Q11-4 Hi (5Vdc)
A2U9-10 cycle power 2.9 s burst 1.25KHz sq. wave
A2U9-15 cycle power one 840ms pulse then Hi at 2.5 sec
A2U9-14 cycle power three 420 ms pulses then Hi at 2.9 sec
A2U9-1 cycle power transition Lo to Hi at 1.7 s
A2U15-10 cycle power transition Lo to Hi at 2.9 s
(ACFAULT )
A2Q7-C cycle power transition 5.0 to 0.3Vdc at 2.5 sec

RELAY ENABLE

*Node( - ) = A2J7-4
Troubleshooting DC-To-DC Converter
Parallel NOR gates A4U1, A4U2 and A4U3A act as drivers and switch on FET s A4Q1,Q2,Q3 and Q4 through pulse
transformer A4T1. NOR gate A4U3B turns off the FETs through pul se transformer A4T2 and transistors A4Q5 and A4Q6.
Circuits Included. On-Pulse Driver, Off-Pulse Driver , FET Switches and Drivers on A4 FET board.
Setup. The Main Troubleshooting Setup, Paragraph 3-40. Apply the ac mains voltage to the isolation transformer, set the
external supply to 40Vdc, and switch on the LINE switch. Set the unit's output voltage to 20Vdc and current to above 1Adc.
Using the DISPLAY SETTINGS switch. Verify that the OVERRANGE LED lights. See Figure 3-7 for waveforms.