Tektronix 1A5 Instruction Manual page 43

Maintenance — Type 1A5
Point
P 1 1-1
P 1 1-2
P11-3
P11-9
P 1 -10
P 1 1-11
>0.5 kΩ
P 1 1-15
J101
J201
TP160
TP260
J150-A
J150-B
J150-C
J150-E >0.25 kΩ
J150-F
J150-J
J150-K
tion. The presence of s e m i -conductors can cause the read ­
ing of a specific instrument to vary from the values given.
The ohmmeter used to take the readings can produce an
apparent difference. It is
readings of each ins t rument be taken while in proper oper ­
ating condition, us i ng the s a
norm a lly be used for troubleshooting.
in the table for these individual readings and they should
be updated after each c a libration to remain reliable.
Switches
R ota ry switch wafers are coded with a number and a
letter. The number indica t es the wafer pos
ass e m b ly, counting from the front (m
ters "F" and "R " indicate whether the front or rear of the
wafer performs the s w itching function.
switch s ect ion des i gnated 2R is contained on the rear of
the s e c o nd wafer as viewed from the front of the switch.
Individual wafe r s or mechanical par
are norm a lly not replaced. If a s
the entire ass emb ly. Wi r ed
switches are availab l e; refer to the P
bers.
P ro cedures for the removal of most switches are gene
ly obvious. When a switch is removed, make careful nota ­
tion of the leads to the switch for insta
4-6
TABLE 4-3
Typical Resistance Values
Conditions: Type 1A5 removed from oscilloscope.
Control settings — POLARITY 0, POSITION midrange, DISPLAY A-B
Ohmmeter setting — R X 1 k
Meter current limited to less than 2 mA; 1.5 V supply
All readings taken with respect to chassis ground.
Re si s tance
8 kΩ
0
8 kΩ
12 kΩ
5.5 kΩ
10 kΩ
Inf
Inf
12 kΩ
12 kΩ
0
0
2 kΩ
5.5 kΩ
2 kΩ
22 kΩ
therefore recommended that
me type ohmmeter which will
Space is provided
i tion in the switch
o unting end). The let ­
F o r example, a
t s of rotary switches
w itch is defective, replace
and unwired replacement
a rts Lis t for part num ­
ra
l lation reference.
Resistance With
Leads Reversed
7 kΩ
0
7 kΩ
18 kΩ
5.5 kΩ
10 kΩ
>0.5 kΩ
Inf
Inf
33 kΩ
33 kΩ
0
0
>30 kΩ
>0.25 kΩ
7.5 kΩ
>30 kΩ
25 kΩ
Use extreme care
switch terminals.
ing around and beyond the rivet will destroy
the contact ' s spring tension.
damage plastic switches.
Component Replacement
Many electrical components are mounted in a
particular way to reduce or control stray capac ­
itance and inductance. Parts orientation and lead
dress should duplicate the original installation.
When a repair is made, a performance check
(contained in Section 5)
and the instrument should be recalibrated as nec ­
essary.
l ­
Disconnect the instrument from the power source
before removing or replacing components.
Comments
1 M Ω with SW101 at DC
1 M Ω with SW201 at DC
CAUTION
when soldering wafer-type
Excessive heat, or so lder flow ­
Excessive heat will
NOTE
should be performed
WARNING