Zenith D952X - Page 16

3. Small stiff glue brush (for solder removal). ,.
4. Metal pick (soldering aid).
5. Pencil type soldering iron with a small tip (25 watts or
less).
6. Tin leads on component before soldering.
7. Use only solder with an extremely low melting point
(60% Tin, 40% Lead).
WARNING: Excessive heat may damage the circuit board foil
during component replacement if a soldering pencil, iron or
gun of higher wattage rating is used.
If a unit, such as the oscillator coil or I.F. transformer is to be
removed, heat the mounting lugs with a pencil type soldering
iron and move them away from the soldered connection with a
long nose pliers or metal pick. Continue heating the lugs and
brush away the molten solder with a small stiff glue brush.
Remove the defective unit. Before inserting the new unit, be
certain that the lug holes are open and free from solder.
Forcing a lug against a solder filled hole may break the bond
between the chassis base and the wiring foil. Exercise care
when replacing units. An open or damaged section of circuit
board wiring foil can be repaired by soldering a short jumper
wire across the points to be connected. When soldering low
voltage electrolytics, transistors and diodes, the wire should be
held with a pair of long nose pliers. The long nose pliers will
act as a heat sink.
FM ALIGNMENT
Alignment of these chassis will, in most cases, not be necessary
unless an RF or IF transformer is replaced or if someone has
tampered with the adjustment.
Because of the wide band pass required in the multiplex FM
tuner, it is desirable to use an FM signal generator having a
deviation of 400 KHz with a sweep rate of 60 Hertz as well as
an oscilloscope when aligning both the IF and RF FM portions
of this receiver. It is not only necessary to obtain maximum
amplitude in the IF amplifier stages, but also necessary to
maintain symmetry. It is desirable to use 10.6, 10.7 and 10.8
Megahertz markers in obtaining IF curve symmetry.
Capacitors mentioned in the alignment procedure should be as
small as possible and the ground lead of the generator must be
connected to ground as close as possible to the point of
injection.
AM ALIGNMENT
A V.T.V.M. on low AC scale connected across the speaker
voice coil output terminals (either left or right channels), will
be satisfactory for all AM, IF and RF adjustments.
Detector Probe -
If your oscilloscope is not equipped with a
detector probe, one can easily be constructed.
For best results the probe should be shield 
ed.
Scope Pattern - B
10.6 and 10.8 MHZ markers must be
symmetrically positioned with 10.7 MHZ
at center of curve. This point must be ad 
justed for maximum.
Scope Pattern - A
Adjust for maximum amplitude while main*
taining linearity and symmetry. 10.7 MHZ
marker must be on the curve at base line.