Agilent Technologies 5517B Operation And Service Manual page 93

U4 1
U4 7
If no problem is found, proceed to step f.
Test jumpers and shorting wires remain in place if continuing with step f. If ending test procedure at this point,
remove shorting wires and return all test jumpers to their left-most position.
f. Set HTR OK to HI, -REF ON to HI, RESET to TEST. Connect A3TP2, A3TP3, and Pin "X" of HTR OK
jumper to ground (A3TP1 or A3TP18). Connect signature analyzer test leads as specified in step d. Set
up the signature analysis Clock, Start, and Stop signals for falling edge detection. Using the signatures
listed in step t, localize the defective element by using standard signature analysis troubleshooting.
Use the A3 schematic to trace faulty signals back to their source. Check A3U1 (Pin 6), A3U19 (Pin
10), and A3U2 (Pin 6) immediately, since these are critical points. If no trouble is found, go to step g.
If proceeding with step g, leave all test jumpers and shorting wires in place. If ending test procedures
at this point, remove shorting wires and return all test jumpers to their left-most position.
g. Remove ground connection on HTR OK jumper. Is A3U8 (Pin 6) signature P3P7? If not, A3U8A or
A3R48B is faulty. If so, go to step h or see Warm-Up Error Amplifier Troubleshooting.
h. Remove the ground connection on A3TP3 and leave off. Is the +5V signature (A3TP9) CP5P? If not,
go to step i. If so go to step k.
I. Set HTR OK to LO. Is A3U8 (Pin 5) low? If not, A3U8 is bad. If yes, go to j. j. Is A3TP3 high? If yes, go to k. if
no, check A3U4B, U5D, U19D, R5D.
k. Remove ground connection on A3TP2 and leave off. Set HTR OK to HI. Is +5V signature AF7A? If yes, go to step
n. If no, go to step 1.
I. Remove RESET jumper. Tie center pin to +5V. Is A3TP2 high? If not, replace A3U1, A3U19, or A3R5. If So, go to
m.
m. With settings same as step 1, check that A3U4 pins 1, 2, 9, 12, 13, and 16 are all high. If not, A3U4 is bad. At this
point, the digital section should be OK. Remove shorting wire.
n. Set -REF ON to HI, HTR OK to "X", and ALL other jumpers to left. A3U8 (Pin 5) (HTRQ) should be high. If not,
check A3U8A. If so go to step o.
o. Keep -REF ON to HI, set HTR OK to LO. A3U8 (Pin 5) (HTRQ) should be low. If not, A3U8A is bad. If so, go to
step p.
p. Set -REF ON to LO. A3U1 (Pin 5) (POR) should be low. If not, A3U2B is bad. If so, go to step q.
q. Return HTR OK and -REF ON jumpers to NRM. The READY LED should start blinking in a minute or two. If
yes, go to step s. If no, check Al R8 and Al DS7.
r. Turn power off. Set -REF ON to HI. Set POWER AMP jumper to UP. Turn power on and allow the laser head to
run for five minutes. Observe the voltage level at A3U2C (Pin 8) with an oscilloscope. Pin 8 will be at TTL low and
will periodically go high (>2.4 Vdc) for a few seconds (approximately 2 seconds). The laserhead will go through the
following cycle and can be monitored by observing the rear panel READY and LASER ON (or the corresponding
LEDs mounted on A3) and the oscilloscope display. The cycle begins with both LEDs off and the voltage at A3U2C
(Pin 8) at TTL low. The READY LED begins flashing and continues to do so for approximately 150 seconds. About
100 seconds into the cycle the laser beam and the LASER ON LED turn on. The READY LED continues to flash.
After 1 50 seconds, the READY LED stops flashing and remains on steady. Both LEDs remain on only momentarily.
At this point, the DISABLE line goes high, and the laser beam and both LEDs turn off. This cycle is repetitive with
the test jumpers set as they are. If the cycle occurs as described, remove power and return all jumpers to their NRM
or - 300 Hz
= F(U4 pin 15/10)
or - 3 Hz
- f(U4 pin 1/10)
or - 3 Hz
U4
U4