Table 3-10. Performance Failure Symptoms

 

 

 

 

DEFECTIVE

 

 

SYMPTOMS

 

BOARD

 

CHECK FUNCTIONAL CIRCUITS

 

unexplained OVP shutdowns

 

A2

 

OVP circuit, CV circuit

 

no current limit

 

 

A2

 

CC circuit

 

max current < specified

 

A2

 

CC Clamp, CC circuit

 

max power < specified

 

A2, A1

 

Power Limit, 20KHz clock, transformer AlT1

 

max voltage < specified

 

A2, A1

 

CV Circuit, diodes A1CR1-CR4

 

cycles on & off randomly

 

A2, A1

 

AC-Surge-&-Dropout Detector, Mains Voltage

 

 

 

 

 

 

 

Select switch A1S2

 

CV overshoots

 

 

A2

 

A2U5A, A2CR19, A2R62

 

output noise (<1KHz)

 

A2,A1

 

CV circuit, input filter

 

output noise (>1KHz)

 

A1, A4

 

transformer AlT2, Output Filter, snubbers A4R1 to

 

 

 

 

 

 

 

A4R11, A4R13 to A4R19, A4C1 to A4C4, A4CR2,

 

 

 

 

 

 

 

A4CR3, A2R15, A2C2

 

CV regulation, transient

 

A2, A1

 

wrong sensing

 

response, programming time

 

 

 

low ac mains voltage, CV circuit

 

CC regulation

 

 

A2

 

low ac mains voltage, CC circuit

 

CV oscillates with capacitive

 

A2

 

A2R61, A2R60, A2R58, A2R59, A2C33, A2R64,

 

loads

 

 

 

 

A2R68, A2C36, A2C37, A2U5, A2R65

 

CC oscillates with inductive

 

A2

 

A2R61, A2R60, A2R58, A2R57, A2C33, A2R19

 

loads

 

 

 

 

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)

 

 

 

 

 

 

 

 

Status of FET On/Off-Pulses

 

 

 

 

 

 

 

 

 

 

 

 

PWM-ON

 

PWM-OFF

DEFECTIVE

 

CHECK FUNCTIONAL CIRCUITS

 

A2J7-26

 

A2J7-25

 

BOARD

 

 

 

Lo

 

Lo

 

A2

Control ckts: CV & CC thru On- & Off-Pulse Oneshots *

 

Lo

 

Hi

 

A2&A4

PWM and DC-to-DC Converter: A4 PFETS probably failed

 

Hi

 

Lo

 

A2&A4

PWM and DC-to-DC Converter: A4 PFETS probably failed

 

Hi

 

Hi

 

A2&A4

PWM and DC-to-DC Converter: A4 PFETS probably failed

 

Lo

 

N

 

A2

A2U15A, On-Pulse Oneshot and Q11

 

N

 

Lo

 

A2&A4

Off-Pulse Oneshot and DC-to-DC: A4 PFETS probably failed

 

Hi

 

N

 

A2&A4

A2U15A, On-Pulse Oneshot & DC-to-DC: A4 PFETS probably failed

 

N

 

Hi

 

A2&A4

Off-Pulse Oneshot and DC-to-DC: A4 PFETS probably failed

 

N

 

N

 

A2&A4

Power-Limit Comparator and DC-to-DC: A4 PFETS probably failed

 

Lo= TTL low

 

Hi= TTL high

 

N= normal 20KHz pulse train, TTL levels

 

* 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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Agilent Technologies 6032A, 6035A, 6031A, 6030A Performance Failure Symptoms, Status of FET On/Off-Pulses, A2J7-26 A2J7-25