36
A2U18-13 cycle power five 100ms pulses then hi
A2U18-12 cycle power two 200ms pulses then hi
A2U18-15 cycle power transition lo to hi at 800 msec
A2U17-8 cycle power transition lo to hi at 1.0 sec
A2U17-11 cycle power transition lo to hi at 1.1 sec
DROPOUT A2Q5 (col)
(RELAY ENABLE)
cycle power transistion 5.0 to 0.3Vdc at 1.0s
Troubleshooting PWM & Clock
The inputs to inhibit Gate A2U19A and PWM gate A2U19B are the keys to PWM troubleshooting. The 20KHz clock starts
each PWM output pulse, and the pulse stops when any of the inputs to A2U19A or A2U19B goes low. The PWM is
inhibited and prevented from initiating output pulses as long as any of the eight inputs is low.
Circuit Included. Pulse Width Modulator (PWM), Inhibit Gate A2U19A, Off-Pulse Oneshot, On-Pulse Oneshot, A2U17B,
20KHz Clock.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer and switch on the
LINE switch. Adjust the units current setting above 1.0Adc. Set the external supply (EXTERNAL) and adjust the unit's
voltage setting (INTERNAL) as instructed below.
Inputs:
NODE ( - ) = A2J7-4
NODE ( + ) SETUP MEASUREMENT SOURCE
A2J3-1 5.0Vdc A2Q3 (emitter)
A2U19-1 Hi A2U17D-11
A2U19-2 Hi remote inhibit
A2U19-4 Hi A2U14-1,8
A2U19-5 Hi A2U11B-6
A2U19-10 Hi A2U16-7
A2U19-12 POWER LIMIT fully CCW Lo A2U14-2
A2U19-12 POWER LIMIT fully CW Hi A2U14-2
Outputs:
SET VOLTAGE (Vdc)
NODE ( + ) EXTERNAL INTERNAL SETUP MEASUREMENT
A2U21-7 0 0 TTL sq wave, 320KHz
A2U22-3 0 0 TTL sq wave, 160KHz
A2U22-6 0 0 TTL sq wave, 20KHz
A2U13-5 0 0
23.5
µs TTL pulses, 20KHz
A2U13-9 0 0
23.5
µs TTL pulses, 20KHz
A2U14-2 40 0 POWER LIMIT
fully CCW
lo
A2U19-5 40 0 lo
A2U13-9 40 0 lo
A2U17-6 40 0 lo
A2U15-13 40 0 lo
A2U15-5 40 0 lo
A2U17-6 40 0 POWER LIMIT
fully CW
groups of 4 pulses 1.7
µs, TTL, 20KHz
A2U17-5 40 0
1.7
µs, TTL, 20KHz
