Agilent Technologies AGILENT MODELS 6023A and 6028A Troubleshooting PWM & Clock, Relay Enable

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
		A2Q5 (col)	cycle power	transistion 5.0 to 0.3Vdc at 1.0s
	DROPOUT
(RELAY ENABLE)

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∝s TTL pulses, 20KHz
A2U13-9	0	0		23.5∝s TTL pulses, 20KHz
A2U14-2	40	0	POWER LIMIT	lo
A2U19-5	40	0	fully CCW	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	groups of 4 pulses 1.7∝s, TTL, 20KHz
A2U17-5	40	0	fully CW	1.7∝s, TTL, 20KHz

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