Agilent Technologies AGILENT MODELS 6023A and 6028A

Table 3-2. No-Output Failures

(Bias supplies and AC turn-on circuit functioning)

Status of PFET on/off-Pulses

PWM-ON

A2J7-26

PWM-OFF

A2J7-25

DEFECTIVE

BOARD

CHECK FUNCTIONAL CIRCUITS

lo lo A2 Control ckts: CV & CC thru on- & off-Pulse Oneshots *

lo hi A2 & A4 PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed

hi lo A2 & A4 PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed

hi hi A2 & A4 PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed

lo N A2 A2U17B,on-Pulse Oneshot and A2Q6A

N lo A2 & A4 Off-Pulse Oneshot and DC-to-DC: A4Q3 and A4Q4 probably failed

hi N A2 & A4 A2U17A, on-Pulse Oneshot & DC-to-DC: A4Q3, and A4Q4 probably

failed

N hi A2 & A4 off-Pulse Oneshot a nd DC-to-DC: A4Q3 and A4Q4 probabl y failed

N N A2 & A4 Power-Limit Comparator and DC-to-DC: A4Q3 and A4Q4 probably

failed

lo= TTL low hi= TTL high N = normal 20KHz pulse train, TTL levels

* Decide which to troubleshoot -- the CV Cir cuit, the CC Circuit, or the PWM and Off-P ulse & On-Pulse Oneshots -- by

measuring the CV CONTROL (A2CR24, cathode) and the CC CONTROL (A2CR19 cathode) voltages. Troubleshoot

whichever is negative, and if neither is negative, troubleshoot the PWM. Make these voltage measurements after you ha ve

implemented the Main Troubleshooting Setup.

Table 3-3. Front-Panel Board Tests

Signal Name Measureme

Description Source

1 +7.5V 7.5V Derived from + 15V bias. A3VR2, A3R3

2 -1V -1.0V Derived from –15V bias. A3R86, A3R85, A3C17

*3 CV VOLTAGE 0-5V For 0 to full scale output voltage. A3U2-2, A3R1, A3R87.

*4 CC VOLTAGE 0-5V For 0 to full scale output current. A3U3A-1, A3R67

5 VOLTS test -1888 on

volts display

Jumper to + 5V on A3 board. A3U4-37

6 AMPS test -1888 on

amps display

Jumper to + 5V on A3 board. A3U5-37

*7 VOLTS input 0-1V For 0 to full scale output voltage. A3R8,A3U7-2,3,10

8 VOLTS low range TTL high If VOLTS display is below 20 volts

(press DISPLAY SETTINGS).

A3U9C-13, A3U6B

9 DISPLAY

SETTINGS

TTL high If DISPLAY SETTINGS switch on

front-panel is depressed.

A3S1,A3R80

10 DISPLAY OVP TTL high If DISPLAY OVP switch on front-

panel is depressed.

A3S2,A3R82, A3U6C-8

*11 AMPS input 0-150mV For 0 to full scale output current. A3R65,A3R66,A3R67

12 -5 V -5.0V Derived from -15 V bias. A3VR1, A3R2

13 buffered OVP 0-2.2V 1/10 of OVP voltage setting when

DISPLAY OVP switch is

depressed. Varies with OVP

ADJUST pot.

A3U3B-6,A3CR5,A3R72

* Switch A1S4 should be in the NORM position for these tests.