Section VIII
TM 11-6625-2781-14&P-2
SERVICE SHEET 10
TEST PROCEDURE 2
It is assumed that the trouble has been isolated to that portion
Connect ohmmeter between ground and XA5-13.
of the Scan Width Attenuator Assembly A2 shown in Service
SCAN WIDTH - ZERO or 0-100 MHz
Correct
Incorrect
TROUBLESHOOTING PROCEDURE
PER DIVISION
Reading
Reading, Check
0Ω
.02 -20 kHz
Since there are no active components in the circuit to be
.05
56
R20, R21 R22
repaired, the 8553B should be disconnected from the IF
0.1
20
R23, R19,
Section and the main frame, and an ohmmeter used for point-
0.2
40
R24
to-point measurements.
0.5
96
R25, R26
1.
180
R27
The following charts should isolate any trouble to a specific
2.
320
R28
resistor, switch contact, or wire. Since each resistor is
5.
500
R29, R30
checked more than once, it is possible to verify resistor failure
10.
0
through different settings of S1 and S2 of A2.
SCAN WIDTH - PER DIVISION
EQUIPMENT REQUIRED
Correct
Incorrect
Volt-ohm-ammeter ....................................................... HP 410C
PER DIVISION
Reading
Reading, Check
0Ω
.02 -20 kHz
TEST PROCEDURE 1
.05 MHz
55
R20, R21, R22
0.1
20
R23, R19
Connect ohmmeter between ground and P3-31 or S1-1F-20.
0.2
40
R24
NOTE: It is difficult to take readings from P3-31 without
0.5
100
R25, R26
shorting to adjacent pins. S1-1F-20 (white-orange-yellow
1.
200
R27
lead) is readily accessible from the bottom of the unit.
2.
400
R28
5.
950
R29, R30
SCAN WIDTH - PER DIVISION
10.
1850
R32
Correct
Incorrect
PER DIVISION
Reading
Reading, Check
TEST PROCEDURE 3
18Ω
.02 kHz
R20
Connect ohmmeter between orange lead of A4 Pre-
.05
40
R21
set Scan Assembly and XA5-13.
0.1
56
R22
0.2
20
R19, R23
23.8K in all positions of switch.
0.5
52
R25, R24
1.
102
R26
SCAN WIDTH - PER DIVISION
2.
200
R27
5.
500
R28, R29
Correct
Incorrect
10.
950
R30
PER DIVISION
Reading
Reading, Check
1850Ω
20.
1850
R31
.02 to 20 kHz
Any except R20,
.05 to 10 MHz
0
R21, R22, R23
SCAN WIDTH - ZERO or 0-100 MHz
.05 MHz
1850
R19 thru R23
0.1
1825
Correct
Incorrect
0.2
1800
PER DIVISION
Reading
Reading, Check
18Ω
0.5
1760
.02 kHz
R20
1.
1670
.05
40
R21
2.
1470
0.1
56
R22
5.
960
0.2
20
R19, R23
10.
0
0.5
52
R25, R24
1.
96
R26
2.
178
R27
5.
375
R28, R29
10.
500
R30
20.
0
.05 to 10 MHz
0
8-42
