Agilent Technologies 6612B, Service Manual, Page: 33 / 74

Troubleshooting - 3
33
Reset the OV and
observe the OV_SCR*
signal. Each time OV is
reset (Shift, Prot Clr)
the unit will generate
another OV. The OV
pulse (OV_SCR*) is
5us long.
A1R378,
OV_SCR* pulse
low 5us?
Check A1R301, C353,
U302A, R378 and A2
Interface Board
No
A1Q301 emitter
pulses high 5us?
Check Q301, U302A
and all associated
resistors and
capacitors
Yes
No
Check A1CR301
Yes
Program the output
voltage and current to
the full scale value and
the OV to 1/2.
OV_Prog @
A1R321 =2V
?
A1 U327-3 0V
?
A2 Interface Board or
cable W8 defective
Check A1R382, R401,
Imon_comp (0V) and
U327
Yes
No
No
A1U327-2 Neg.
?
Yes
Check A1R321, R387,
R391, R405, C349,
C317 and U327
No
A1U327-7,
OV_DETECT*,
Low?
Yes
Check A1U327
No
"G" From Sheet 3
Yes
Figure 3-1 Sheet 11. Unit Did Not Overvoltage