A7 Board - HP 3580A Operating And Service Manual

Section VII
A3TP6:
>
+6 V
A3TP5: 0 V ± .1 V
A3TP8: + 9.5 V ± .5 V
Collector A3Ql6: - 9.9 V ± .1 V
3. Reposition:
RESOLUTION BANDWIDTII . . . . . 1 Hz
4. Connect an oscilloscope to the collector of
A3Ql l. Wait 5 seconds. The voltage should be
a TTL HIGH (;;;;.. 2 V de).
5. Adjust A3Rl4 fully CCW*.
6. While watching the oscilloscope clock Sl. The
oscilloscope should indicate a TTL LOW
( < .8 V) for a few seconds and then return
HIGH. The logic state should be 011.
v. State 011
1. Check the following levels:
A3TP5: OV de± .1 V
A3TP6: 0 V de ± .1 V
Collector of A3Ql6: - 9.9 V ± .1 V
A3TP8: TTL LOW ( < .8 V)
2. Reposition:
RESOLUTION BANDWIDTII . . . 100 Hz
3. Clock Sl and the control logic should go to
state 001.
w. StateOOl
1. Clock Sl and observe no change of state.
2. Check the following levels:
Collector A3Q16: - 9.9 V ± .1 V
A3TP5: <-7 V
A3TP8: TTL LOW ( < .8 V)
3. Adjust A3Rl4 fully CW*. Clock SI, and the
control logic should go to State 101.
x. Adjust R14 so that the voltage at A3TP1 l is at the
transition between a plus and minus voltage.
y. Remove all test leads and replace the clock jumper.
The 3580A should sweep normally. The penlift relay
should "click" in single sweep mode and the output of the
A3 RAMP GENERATOR (A3TP1) should be + 5 volts
nominal for a front panel display indication at the right
graticule. If the LOG SWEEP mode will not work, see the
A3 schematic notes.
Model 3580A
7-12. A7 Board.
7-13. The A 7 Board (03580-66507) is available as a rebuilt
exchange board (03580-69507) through your local -hp-
Sales and Service Office. Many times, however, the board
can be repaired without purchasing an exchange board. The
following procedure will aid in determining whether the A 7
board or the analog circuits preceeding
the~
A 7 board are at
fault.
a. Connect the 3580A X-AXIS output on the rear panel
to the X deflection EXT INPUT of an oscilloscope. A scope
with variable persistance works best but is not absolutely
necessary. Connect the 3580A Y-AXIS output to the
vertical input of the scope. This procedure effectively half
splits the 3580A for troubleshooting purposes.
1. If the signal seen of the scope is correct and the
signal seen on the 3580A display is incorrect then
the problem is in the A7, A8, or A13 boards. If
the signal seen on the scope is incorrect DO NOT
troubleshoot the A 7 board until repiii.rs are made
to preceeding circuitry. (See Functional Block
Diagram in the Operating and Service Manual.)
2. If the scope presentation is good but the 3580A
display is incorrect, check A 7TP1. If the presenta-
tion is bad there then troubleshoot the A 7 board,
otherwise troubleshoot A8 or Al3.
7-14. Troubleshooting the A 7 board.
a. Check A7Q2, Q4, Q6, Q8, and Q9. If these parts are
P/N 1853-0098 replace all 5 of them with P/N 1853-0010.
The new type is much more reliable and is being used in all
instruments with serial numbers above 1415A01276.
b. Check
A
7TP4 and
A
7TP5. They should look similar
to the figure shown below.
Horiz 2 µ sec/div
Vert .2 V/div (with 10:1 probe)
TP4
TP5
The frequency must be 55 K - 70 kHz! If the frequency is
off check A8TP9. The clock frequency is determined by
the A8 board.
*If A3R14 has a black casing, set it opposite to the setting given.
7-4