Battery; Transistors And Integrated Circuits; Soldering Techniques - Tektronix 2246 1Y Service Manual

BATTERY

The 2246 1Y instruments serial numbered B714999
and below use a pair of silver-oxide cells with an life
expectancy of 1 year. Above this serial number, the
2246 1Y uses a lithium battery. The 2246 Mod A uses
a lithium battery.
The battery is used to supply backup power to the
System RAM and should last for at least 5 years.
When it becomes necessary to replace the battery,
be sure to observe the following general warning
about disposal of lithium batteries.
WARNING ^
To avoid personal injury, observe proper pro­
cedures for handling and disposal of lithium
batteries. Improper handling may cause fire,
explosion, or severe burns. Do not recharge,
crush, disassemble, heat the battery above
212°F (100°C), incinerate, or expose con­
tents of the battery to water. Dispose of
battery in accordance with local, state, and
national regulations.
T y p ic a lly , s m a ll q u a n titie s ( le s s th a n 2 0 ) c a n
b e s a fe ly d is p o s e d o f w ith o r d in a r y g a r b a g e in
a s a n ita r y la n d f ill. L a r g e r q u a n titie s m u s t b e
s e n t b y s u r fa c e tr a n s p o r t
w a s te d is p o s a l fa c ilit y . T h e b a tt e r ie s s h o u ld
b e in d iv id u a lly p a c k a g e d to p r e v e n t s h o r t in g
a n d p a c k e d in a s t u r d y c o n ta in e r th a t is c le a r ly
la b e le d " L ith iu m B a tt e r ie s — D O N O T O P E N . "
TRANSISTORS AND INTEGRATED
CIRCUITS
Transistors and integrated circuits should not be
replaced unless they are actually defective. If one is
removed from its socket or unsoldered from the
circuit board during routine maintenance, return it to
its original board location. Unnecessary replacement
or transposing of semiconductor devices may affect
the adjustment of the instrument. When a semi­
conductor is replaced, check the performance of any
circuit that may be affected.
Any replacement component should be of the
original type or a direct replacement. Bend com ­
ponent leads to fit their circuit board holes, and cut
the leads to the same length as the original com ­
ponent. See Figure 9-2 in the Diagrams section for
the semiconductor lead-configurations.
REV OCT 1991
to a h a z a r d o u s
M a in ten a n ce —2246 1Y and 2246 M od A Service
I CAUTION |
t v w w w v r S
A f t e r r e p la c in g a p o w e r tr a n s is t o r , c h e c k th a t
th e c o lle c t o r is n o t s h o r t e d to
b e fo r e a p p ly in g p o w e r to th e in s tr u m e n t.
To remove socketed dual-in-line packaged (DIP)
integrated circuits, pull slowly and evenly on both
ends of the device. Avoid disengaging one end of the
integrated circuit from the socket before the other,
since this may damage the pins.
To remove a soldered DIP 1C when it is going to be
replaced, clip all the leads of the device and remove
the leads from the circuit board one at a time. If the
device must be removed intact for possible reinstalla­
tion, do not heat adjacent conductors consecutively.
Apply heat to pins at alternate sides and ends of the
1C as solder is removed. Allow a moment for the cir­
cuit board to cool before proceeding to the next pin.

SOLDERING TECHNIQUES

The reliability and accuracy of this instrument can be
maintained only if proper soldering techniques are
used to remove or replace parts. General soldering
techniques that apply to maintenance of any pre­
cision electronic equipment should be used when
working on this instrument.
WARNING
To a v o id a n e le c t r ic - s h o c k h a z a r d , o b s e rv e
th e fo llo w in g p r e c a u t io n s b e fo r e a tt e m p t in g
a n y s o ld e r in g : tu r n th e in s t r u m e n t o ff, d is c o n ­
n e c t i t fr o m th e a c p o w e r s o u r c e , a n d w a it a t
le a s t th r e e m in u te s f o r th e l in e - r e c t if ie r filte r
c a p a c ito r s to d is c h a r g e .
Use rosin-core wire solder containing 63% tin and
37% lead. Contact your local Tektronix Field Office or
representative to obtain the names of approved sol­
der types.
When soldering on circuits boards or small insulated
wires, use only a 15-watt, pencil-type soldering iron.
A higher wattage soldering iron may cause etched
circuit conductors to separate from the board base
material and melt the insulation on small wires. Al­
ways keep the soldering-iron tip properly tinned to
ensure the best heat transfer from the tip to the sol­
der joint. Apply only enough solder to make a
firm joint. After soldering, clean the area around
th e c h a s s is
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