Maintenance— Type TU-7
3. Use a hot iron for a short time. A 50- to 75-watt iron
with good heat storage and transfer properties is ade
quate.
4. Avoid putting pressure on the strip with the soldering
iron or other tools. Excessive pressure may cause the
strip to crack or chip.
Soldering to Etched-Wiring Boards:
1. To remove a component, cut the leads near the body. This
frees the leads for individual unsoldering.
2. Grip the lead with needle-nose pliers. Apply the tinned
tip of a 40-watt pend! soidering iron to the lead between
the pliers and the board; then pull gently.
3. When the solder first begins to melt, the lead will come
out, leaving a clean hoie. If the hole is not clean, use
a scribe or pointed tool and the soldering iron to open
the terminal hole.
4. Bend the leads on the new component to the correct shape
and carefully insert the leads into the holes.
5. Apply the iron for a short time at each connection on the
side of the board opposite the component to properly
seat the component.
6. Apply the iron and a little solder to the connections to
finish the soider joint.
7. Clip any excess lead that extends through the board.
Ceramic Terminal Strips
Fig. 4-1 shows an assembled ceramic terminal strip. Re
placement strips with studs attached are supplied under a
single part number and spacers under another number. The
original spacers may be reused if undamaged.
Usually, a strip can be pried out of the chassis or pulled
out with a pair of pliers. In some cases, you may choose to
use a hammer and punch to drive out the studs from the
opposite side of the chassis.
Fig. 4 -1 . Ceramic Term inal S trip Assembly.
When the damaged strip has been removed, place new
or used (but undamaged} spacers in the chassis holes. Then
carefully force the studs of the new strip into the spacers un
til they are completely seated. If necessary, use a soft-faced
mallet and tap lightly over the stud area of the strip.
Switch Replacement
Individual wafers normally are not replaced in switch
assemblies. Replacement switiches may be ordered from
Tektronix either unwired or with the associated wires and
components attached. See Section 6.
When soldering leads to a switch, do not let soider flow
around and beyond the terminal rivet as this may destroy
the contact spring tension.
Tubes and Transistors
Tubes and transistors should not be replaced unless actu
ally defective. When a defect is suspected, it is suggested
that circuit conditions be checked first to be certain that a
replacement tube or transistor will not be immediately de
stroyed. In some cases, these checks will also show whether
or not the tube or transistor is at fault.
When circuit conditions are known to be safe, install a
tube or transistor that is known to be good and check for
proper operation. If the original tube or transistor proves
acceptable, return it to its original socket to avoid un
necessary recalibration.
TROUBLESHOOTING
Operational Checks
If trouble is encountered in the Type TU-7, first perform
a visual inspection of the entire unit. If a visual inspection
does not reveal the cause of trouble, change tubes or tran
sistors, depending on the area of the trouble.
As a troubleshooting aid. Table 4-1 provides resistance
values to ground at the terminals of the 16-pin intercon
necting plug at the rear of the unit. The resistance measure
ments were taken with the unit disconnected from the oscil
loscope. The measurements are not absolute since semi
conductors are used in the circuitry. Therefore, for future
reference, blank columns are provided in the table for
recording measurements and type of meter used.
NOTE
To make the unit more accessible fo r servicing, use
either a Tektronix 6 Y2-inch extension (Part No.
0 1 3 -0 5 5 ) or a 30-inch fle x ib le extension (Part
No. 0 1 2 -0 3 8 ). Remember, however, th at if the
TEST FUNCTION switch is set to + PULSE or
— PULSE, the oscilloscope display w ill contain
some overshoot and ringing due to the lead lengths
in the extension.
