Agilent Technologies 6032A Service Manual page 57

SYMPTOMS
unexplained OVP shutdowns
no current limit
max current < specified
max power < specified
max voltage < specified
cycles on & off randomly
CV overshoots
output noise (<1KHz)
output noise (>1KHz)
CV regulation, transient
response, programming time
CC regulation
CV oscillates with capacitive
loads
CC oscillates with inductive
loads
Status of FET On/Off-Pulses
PWM-ON PWM-OFF
A2J7-26 A2J7-25
Lo Lo
Lo Hi
Hi Lo
Hi Hi
Lo N
N Lo
Hi N
N Hi
N N
Lo= TTL low Hi= TTL high
* Decide which to troubleshoot--the CV circuit, the CC circuit, or the PWM and Off-Pulse & On-Pulse Oneshots-- by
measuring the CV CONTROL (A2CR24, cathode) and the CC CONTROL (A2CR11 cathode) voltages. Troubleshoot
whichever is negative, and if neither is negative, troubleshoot the PWM. Make these voltage measurements after you
have implemented the Main Troubleshooting Setup.
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Table 3-10. Performance Failure Symptoms
DEFECTIVE
BOARD
A2 OVP circuit, CV circuit
A2 CC circuit
A2 CC Clamp, CC circuit
A2, A1 Power Limit, 20KHz clock, transformer AlT1
A2, A1 CV Circuit, diodes A1CR1-CR4
A2, A1 AC-Surge-&-Dropout Detector, Mains Voltage
Select switch A1S2
A2 A2U5A, A2CR19, A2R62
A2,A1 CV circuit, input filter
A1, A4 transformer AlT2, Output Filter, snubbers A4R1 to
A4R11, A4R13 to A4R19, A4C1 to A4C4, A4CR2,
A4CR3, A2R15, A2C2
A2, A1 wrong sensing
low ac mains voltage, CV circuit
A2 low ac mains voltage, CC circuit
A2 A2R61, A2R60, A2R58, A2R59, A2C33, A2R64,
A2R68, A2C36, A2C37, A2U5, A2R65
A2 A2R61, A2R60, A2R58, A2R57, A2C33, A2R19
A2C11, A2R28, A2C12, A2U4, A2R35, A2C20,
A2U4, A2R37, A2C17, A2R29, A2C18, A2R31
Table 3-11. No-Output Failures
(Bias supplies and AC turn-on circuit functioning)
DEFECTIVE
BOARD
A2 Control ckts: CV & CC thru On- & Off-Pulse Oneshots *
A2&A4 PWM and DC-to-DC Converter: A4 PFETS probably failed
A2&A4 PWM and DC-to-DC Converter: A4 PFETS probably failed
A2&A4 PWM and DC-to-DC Converter: A4 PFETS probably failed
A2 A2U15A, On-Pulse Oneshot and Q11
A2&A4 Off-Pulse Oneshot and DC-to-DC: A4 PFETS probably failed
A2&A4 A2U15A, On-Pulse Oneshot & DC-to-DC: A4 PFETS probably failed
A2&A4 Off-Pulse Oneshot and DC-to-DC: A4 PFETS probably failed
A2&A4 Power-Limit Comparator and DC-to-DC: A4 PFETS probably failed
N= normal 20KHz pulse train, TTL levels
CHECK FUNCTIONAL CIRCUITS
CHECK FUNCTIONAL CIRCUITS