Model 5261A
Section V
Paragraphs 5-1 to 5-13
SECTION V
MAINTENANCE
5-1.
INTRODUCTION.
5-2.
This section of the manual provides maintenance
and service information for the Model 5261A Video
Amplifier. Included are troubleshooting procedures, a
table of recommended test equipment, repair
information, and in-cabinet performance checks which
may be used to verify proper operation of the instrument.
5-3.
TEST EQUIPMENT.
5-4.
Recommended test equipment for checking
performance and troubleshooting is listed in Table 5-1.
Test instruments not listed that have specifications equal
to or better than the required characteristics listed may
be used.
5-5.
ASSEMBLY IDENTIFICATION.
5-6.
Throughout this manual, printed circuit
assemblies are referred to by assembly number. For
example, the Video Amplifier Assembly is referred to as
A3. Connections to pins of the 50-pin plug on the rear of
the instrument are referred to by the plug number and pin
number; for example, pin 1 is referred to as P6(1).
5-7.
IN-CABINET PERFORMANCE CHECK.
5-8.
The performance checks listed in Table 5-2
verify proper operation of circuits in the Video Amplifier
and may be used:
a. as part of an incoming inspection check of
instrument specifications;
b. periodically, for instruments in systems
where maximum reliability is of primary importance;
c. as part of a troubleshooting procedure to
locate malfunctioning circuits, and
d.
after any repairs or adjustments, before
returning instrument to regular service.
5-9.
ADJUSTMENTS.
5-10.
HIGH FREQUENCY RESPONSE
ADJUSTMENTS A3C4, A3Cll.
5-11.
Trimmer capacitors A3C4 and A3Cll in video
amplifier assembly A3 provide the only adjustments for
frequency response. Adjust these capacitors only when
the bandwidth check (Table 5-2, In-Cabinet Performance
Checks)indicates the frequency response is outside the
±3 db limits. The access hole for tuning A3C4 is on the
bottom of the instrument and A3Cll access hole is on the
left side. Use a plastic tuning wand for adjustments.
Adjust A3C4 and A3Cll as follows
a.
Remove Video Amplifier plug-in from
counter by loosening lock screws and sliding unit out of
counter plug-in compartment.
b.
Use ', 10506B extension cable and connect
Video Amplifier rear plug to counter lack inside plug-ln
compartment.
c. Set counter controls as follows:
SAMPLE RATE............. slightly cw out oA POW'ER OFF
SENSITIVITY................ PLUG-IN
TIME BASE................... 1 MS
FUNCTION ................... FREQUENCY
d.
Set Video Amplifier SENSITIVITY to 3 MV.
e.
Connect Model 411A RF Millivoltmeter
through (hp)10100A feed through termination to 50
Ω
OUTPUT.
f.
Connect Model GOGA generator through
(hp)10100A feedthrough termination to Video Amplifier
INPUT. Set frequency to 1000 kc and adjust output level
for 150 mv indication on voltmeter (use -3 db mark as
reference).
g.
Slowly change generator frequency from
500 kc to 60 Mc. If voltmeter indicates less than -6 db or
more than 0 db. adjust A3C11 to bring the voltmeter
indication within these limits.
h.
Set generator frequency to 30 Mc and it
voltmeter indication is less than -6 db or more than 0db,
adjust A3C4.
i.
Repeat steps g and h until the voltmeter
indication is within the limits for both steps.
j.
Slowly change generator frequency between
500 kc and 60 Mc. Observe that voltmeter indication
remains between -6 db and 0 db over this frequency
range.
5-12.
OUTPUT METER CALIBRATION.
5-13.
Meter Cal potentiometer A4R13 is located on
output amplifier assembly A4 and is accessible from the
top when the Video Amplifier is outside the counter plug-
in compartment. Adjust A4R13 as follows:
a. Perform operations indicated in Paragraph
5-11, steps a, b, and c.
b. Connect Model 200CD oscillator output to
the Video Amplifier INPUT. Set oscillator frequency to
100 kc.
c. Connect Model 403B voltmeter to the Video
Amplifier 50
Ω
OUTPUT through ; 10100A feedthrough
termination.
5-1
Summary of Contents for AM-4380/U 5261A
Page 2: ...A ...
Page 7: ...Model 5261A Section I Figure 1 1 FIGURE 1 1 Model 5261A 1 0 ...
Page 19: ...Model 5261A Section V Figure 5 1 FIGURE 5 1 Schematic Diagram Notes 5 5 ...
Page 20: ...Model 5261A Section V Figure 5 2 FIGURE 5 2 Top View Component Location 5 6 ...
Page 21: ...Model 5261A FIGURE 5 3 Bottom View Component Location 5 7 ...
Page 22: ...Model 5261A Section V Figure 5 3 and 5 4 FIGURE 5 4 Video Amplifier Schematic 5 7 5 8 ...
Page 31: ...TM 11 6625 2906 14 P APPENIDIX C Additional Authorization List Not Applicable C 1 ...
Page 39: ...Model 5261A Appendix E FIGURE A 1 Top View Component Location E 3 ...
Page 40: ...Model 5261A Appendix E FIGURE A 2 Bottom View Component Location E 4 ...
Page 41: ...Model 5261A Appendix E FIGURE A 3 Video Amplifier Schematic E 5 ...
Page 42: ...Model 5261A Appendix E FIGURE A 4 A1 Preamplifier Component Location E 6 ...
Page 43: ...Model 5261A Appendix E FIGURE A 5 Video Amplifier Schematic E 7 ...
Page 44: ......
Page 45: ......
Page 47: ......
Page 48: ...PIN 046855 000 ...