Tektronix 2235 User Manual

M aintenance-2235 Service
2 .
Spray wash
dirty p arts with t he d etergent-and-water

Spray only
for
approximately
five
seconds,
using
an
solution
; then use clean water to thoroughly rinse them .

atomizing
spray device .
S WITCH CONTACTS . T he V OLTS/DIV and THE SEC/
DIV Switches are mounted circuit-boards within t he instru-
ment . Care must b e exercised to p reserve the h igh-frequen-
cy characteristics of these switches . Switch maintenance is
seldom n ecessary, but if it is required, observe the following
precautions .
1 . The V OLTS/DIV switches contain cam-actuated
contacts .
b .
Dry
b
oth t
he
switch
and
the circuit
board on
which it is
3
.
Dry
all
parts with
low-pressure
air .

mounted, using dry low-pressure air .
CAUTION
M ost s p ray-ty p e circuit coola n ts co n tain F reon 12 as
α p ro p ella n t . B ecause many F reons adve r sely affect
switc h contacts, do notuse α s p ray-ty p e coola n ts .
T he only recommended ci r cuit coolants for t he
volts-
division atten u ators a r e d ry ice (CO ) a nd iso p ro p yl
alco h ol .
α . U se only isopropyl alcohol as α cleaning solution, es-
pecially in t he area of the vertical Attenuator circuit
board . Carbon-based solvents will damage the b oard
material .
b . Apply t he alcohol with α small, camel-hair brush . Do
not use cotton-tipped applicators when cleaning
contacts .
c . B ake the switch a nd t he circuit board in an oven at
75°C (167°F) for 15 minutes to eliminate all moisture .
d . Spray α very small amount (only about α 1/2-second
s q uirt) of α recommended l ubricant, such as No N oise,
into the slots at the top of the switch housing .
e . R otate the switch control k nob about 180° and again
spray α very small amount of lubricant into each slot .
LUBR ICATIO N
M ost of the potentiometers u sed in this instrument are
permanently sealed and generally d o n ot require p eriodic
lubrication . All switches, b oth rotary- and
lever-type, are
in-
stalled with prop er lubrication applied w here
necessary and
will rarely require any additional lubrication . Therefore, α
regular p eriodic lubrication program for the instrument is n ot
recommended .
S EM ICO N D U CTO R C HE C KS
P eriodic checks of the transistors and other semiconduc-
tors in the oscilloscope are not recommended . The b est
check of semi-conductor p erformance is actual operation i n
t he instrument .
PER IODIC RE AD JU ST MEN T
2 . The SEC/DIV switch is comprised of r otary-activated

To ensure accurate measurements, check t he p erfor
contacts .

r ' r ι ance of this instrument after every 2000 h ours of opera-
tion, or if u sed infrequently, once each year . In addition,
replacement of components may necessitate readjustment
CΑ υ Ti ON

of the affected circuits .
U se on ly h ot d e ί on ize d or distilled water, 55°C

Complete P erformance Check and Adjustment instruc-
(131 OF), to clea n t h e timing switc h in t h is instrument .

tions are given in Sections 4 and 5 . The P erformance Check
Tap water co n tai
n
s
im
pu rities w h ic h are left as r esidu-

Procedure can also be h elpful in localizing certain trouble in
als afte r eva p o r atio n
.

t he instrument . In some cases, minor p roblems may be r e-
vealed or corrected b y readjustment . If only α partial adjust-
a . Spray h ot water into the slots at the top of each

ment is p erformed, see the interaction, chart, Table 5-1, for
switch housing while rotating the switch control knob .

p ossible adjustment interactions with other circuits .

Tektronix 2235 Specifications

General

Brand	Tektronix
Model	2235
Category	Test Equipment
Language	English