HP 5300A - Alternate Method

Figure 5-4C. Al1U3 Counter, A1U4 Time Base,
and A1U5 Control Checks (Continued)
INSERT
TEST
7
DISPLAY = @)
10.0000+1
“C" LAMP ON
AT A.1SEC
RATE
OK
DISPLAY IS
ALL ZEROS
ANDO “C* LAMP
DISPLAY LOQKS
MISERY. AS THOUGH
TEST
8 ALL BS ARE FLASHES AT RATE
ON OF .1SEC
CHECK U3 CHECK CHECK U3(4)
(4)
FOR
TRANSFER
POSSIBLE
°
POSSIBLE OPEN LINE OPEN
CIRCUIT us(11) CIRCUIT
CHECK
CONNECTION CHANGE
FOR U3
POSSIBLE
SHORT
CHECK
SOCKET AND
PC BOARD
CONNECTIONS
5-48. ALTERNATE METHOD OF TROUBLE
ISOLATION
5-49. Obtain a female 50-pin connector, HP Part No.
1251-0101 (CINCH 57-20500-375), and hard-wire the
following listed programs by soldering short pieces of
wire to the selected pins (observe CAUTION during
soldering and use).
During soldering and use, do not short
adjacent pins to each other or to the con-
nector case. Damage to the 5300A may
result.
5-50. The following hard wired programs, tests 1
through 4, check out the display circuitry to its fullest
extent. Circuits tested are:
a. UI Scanner circuits to test vertical column
lines (left or right).
b. U2 Character Generator circuits to test hori-
zontal lines (upper or lower).
Model 5300A
Maintenance
c. Q6 to Q1I7 Buffer Drivers for the LED Dis-
play columns.
d. A1A1DS7 light-emitting-diode matrix.
e. Integrated circuit sockets and mechanical
connections. :
5-51. Tests 5, 6, and 7 check the majority of inputs
and outputs to U3, U4, and U5 for the various modes
of operation that can be performed with a plug-on.
Test number 8 checks out the Annunciators and
Decima! Point lines of the Display Assembly.
5-52. Test 9 through 12 and tests 13 through 16 check
the MOS Time Base Circuitry and the MOS Decade
Counter. By varying the input codes and outputs on
U3 and U4 with a fixed program, the special circuits
are exercised.
5-53. Inputs to the 5300A system mainframe and pro-
gramming of its functions are provided from the
plug-on module via a 50-pin connector in the center
of the instrument. For the alternate method of
_ troubleshooting, perform tests listed on Pages 5-12 to
5-14 (connector signals are listed in Table 4-2, AlJ1
Signals).
5-54. OSCILLATOR ADJUSTMENT
5-55. Two methods of oscillator adjustment are
available:
a. Using an electronic counter to measure the
53800A 10 MHz oscillator frequency at the 5300A rear-
panel OSC jack.
b. Using the oscilloscope-drift method to com-
pare the 5300A oscillator drift against a reference or
“house” standard.
5-56. Oscillator Measurement
5-57. The 5300A oscillator can be easily measured by
connecting an electronic counter, whose time base
oscillator stability is at least 10 times better than the
5300A oscillator, to the 5300A rear-panel OSC jack.
To measure the 5300A oscillator frequency proceed
as follows:
a. Obtain an HP Model 5245L/M Electronic
Counter and connect the 5300A OSC jack to the
5245L/M input.
b. Set 52451./M controls for a minimum 7-digit
stable display.
ec. The 52451./M display should read 10.00000
MHz #1 count.
d. If the 52451./M does not indicate this fre-
quency, adjust the 5300A OSC adjustment until the
display is correct.
5-58. The 5300A 10 MHz oscillator can be adjusted
through the rear panel access hole. Adjustment
should be made with the 5300A mated to a plug-on
as part of a periodic maintenance cycle.
5-11