Tektronix T912 - Page 48

Section 5—T912
SERVICE
INFORMATION
The
following
information
is provided
to
help you keep your T91 2 in good
operating
condition. We recommend
that
servicing be done
by qualified
service personnel only.
You
can,
if
you like, send your
instrument
to a Tektronix Service
Center
for
re-adjustment
and repair.
Contact
your local Tektronix representative for
information
about
the
Service
Centers
in your
area.
CABINET
REMOVAL
Dangerous
potentials
exist at several points
throughout
the T912- When
operating
the instru-
ment
with the
covers
off, avoid touching connec-
tions
and components.
Some transistors
have
elevated
cases.
Disconnect the
power
before
clean-
ing the
instrument or replacing
parts.
To remove the
cover,
take out the
six screws (top and
bottom)
holding the
two halves together.
Pull
the two
halves
apart.
To replace the
cover, line
up the slots on the
coverwith
the
front panel and the rear subpanel and slide
together.
Replace
screws.
OPERATING
VOLTAGE SELECTION
Your instrument will
operate from either a 120 V
or
240 V ac 50 to 60 Hz nominal power input source.
Check
that the
Power
Input Voltage
Selector (120V/240V)
switch and the Regulating Range Selector
(HI/LO)
switch
are set to positions that include
the value of the applied
power input
voltage.
In the United
States,
the
120 V/240 V
switch
is
normally
set
for 120 V and the HI/LO
switch
is
normally
set for HI at the factory.
In
Europe, the
120 V/240 V
switch
is set for240 V andthe HI/LO
switch
is
normally
set for LO. The POWER indicator
lamp
will blink
when the applied
power input voltage
varies
more
than
about
10%
(either
high
or
low)
from the value for which the
switches
are set.
Your instrument may
be damaged if it is operated
from
a 240 V power input voltage
source
with the
120 V/240 V switch
set
for 120 V. The
120
V/240 V
switch
and the HI/LO switch are
both visible
from the
bottom of the
instrument in all T900-series
bench
version
oscilloscopes,
but the 120 V/240 V switch
is
not
adjustable
from outside of the cabinet.
Refer
120
V/240
V power input voltage selection
to
qualified
service personnel.
The
120
V/240
V switch
S701 is
accessible
In all T900-
series
instruments
when
the cabinet
is removed.
If S701
setting needs
to be changed, the
value
of the line fuse F700
must
also
be changed.
See Fuse
Replacement
in Correc-
tive Maintenance
portion
of Service
Information
section
of
this manual.
PREVENTIVE
MAINTENANCE
Preventive maintenance
consists of
cleaning
the instru-
ment
regularly and inspecting
itoccasionally
for
broken or
damaged parts.
Regular
maintenance
will
improve the
reliability of your instrument
and prevent
breakdowns.
Cleaning
Accumulations
of dirt
and
dust on components
act as
an insulating
blanket
preventing efficient
heat dissipation.
Dust
on circuit boards
and
wires can cause
arcing and
short
circuits,
resulting in
damage to components
or even
instrument failure.
Your instrument
should
be cleaned
before this
happens!
The cabinet
provides
protection from
dust
and dirt and
should be in place
during
normal operation of the
instrument.
^
CAUTION
I
Avoid the
use of chemical cleaning
agents con-
taining benzene,
toluene,
xylene,
acetone
or similar
solvents. These chemicals
may damage the
plastics
used in this instrument.
Recommended cleaning
agents are
isopropyl
alcohol or Kelitejl
part Kelite,
20
parts water).
Exterior.
Dust the cabinet with a
soft
cloth.
Dust the
front
panel controls with
a
small
soft paint brush. Dirt
clinging
to the surface
of
the
cabinet may be removed with
a
soft cloth
dampened with a mild
detergent and water
solution. Avoid
using abrasive cleaners,
They
will scratch
the cabinet and front
panel.
Interior.
Dust in
the interior of the
instruments
should
be removed before it builds
up enough to cause arcing
and
short circuits
during periods of high
humidity. Dust
is
best
removed from the
interior by dry (approximately
9 Ib/in.^),
low-pressure air. Dirt
clinging
to surfaces may
be
removed
with
a soft paint brush or cloth
dampened with a mild
detergent
and water solution.
Use a cotton-tipped
applicator for cleaning in
narrow spaces and on
the circuit
boards,
Switch Contacts
^CAUTION
Do not
use acetone, MEK, MIBK, benzene, toluene,
carbon tetrachloride,
trichloroethylene,
methyl
alcohol,
methylene
chloride, sulphuric acid, or
Freon
TC,
TE, TF,
TA,
12,
22,
to clean the switch
contacts. Check the contents
of spray
coolants
and
cleaners
before using.
REV B, DEC 1978
5-1