This section of the manual provides maintenance
and service information for the Model 5261A Video
Included are troubleshooting procedures, a
information, and in-cabinet performance checks which
may be used to verify proper operation of the instrument.
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
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).
IN-CABINET PERFORMANCE CHECK.
verify proper operation of circuits in the Video Amplifier
and may be used:
a. as part of an incoming inspection check of
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
after any repairs or adjustments, before
returning instrument to regular service.
ADJUSTMENTS A3C4, A3Cll.
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
Use a plastic tuning wand for adjustments.
checks listed in Table 5-2
counter by loosening lock screws and sliding unit out of
counter plug-in compartment.
Video Amplifier rear plug to counter lack inside plug-ln
c. Set counter controls as follows:
SAMPLE RATE............. slightly cw out oA POW'ER OFF
TIME BASE................... 1 MS
FUNCTION ................... FREQUENCY
through (hp)10100A feed through termination to 50 Ω
(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
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.
voltmeter indication is less than -6 db or more than 0db,
indication is within the limits for both steps.
500 kc and 60 Mc. Observe that voltmeter indication
remains between -6 db and 0 db over this frequency
OUTPUT METER CALIBRATION.
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:
5-11, steps a, b, and c.
the Video Amplifier INPUT. Set oscillator frequency to
Amplifier 50 Ω OUTPUT through ; 10100A feedthrough
Paragraphs 5-1 to 5-13
Use ', 10506B extension cable and connect
Set Video Amplifier SENSITIVITY to 3 MV.
Connect Model 411A RF Millivoltmeter
Connect Model GOGA generator through
Slowly change generator frequency from
Set generator frequency to 30 Mc and it
Repeat steps g and h until the voltmeter
Slowly change generator frequency between
Perform operations indicated in Paragraph
Connect Model 200CD oscillator output to
Connect Model 403B voltmeter to the Video