Heathkit AA-1214 - Page 50

50
► HEATH-
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TEST
IF YOU DO HEAR A MILD HUM IF YOU DO NOT HEAR A MILD HUM
POINT
OR CLICK FROM THE SPEAKER OR CLICK FROM THE SPEAKER
TP9
Proceed to the next l. Transistor Ql03 and Ql04
(Left
channel)
test.
may be incorrectly
TPlO
installed or interchanged.
(Right channel)
2. The brown and white wires
between the tone circuit
board and the amplifier
circuit board may be
incorrectly installed.
AUX
Check your Auxiliary
l. Wiring harness may be
INPUT
equipment and input
incorrectly connected.
SOCKET
cables
Check the inner lead and
(Left channel)
shield lead or shielded
(Right channel)
cables to be sure they are
not interchanged. Check
wiring on pushbutton
switch lugs.
w
( ) Push the Phono pushbutton to ON.
L,
PHONO PREAMPLIFIER SIGNAL INJECTION CHART
TEST
IF YOU DO HEAR HUM
IF YOU DO NOT HEAR
POINT
IN THE SPEAKER
HUM IN THE SPEAKER
L..J
TPll
Proceed to TP13 (left
1.
Phono Level controls
Rl23
(Left
channel)
channel) or TP14
and Rl24 may be full
(right channel)
counterclockwise, poorly
soldered, or faulty.
TP12
2.
Capacitor Clll or Cll2 may
(Right
channel)
be incorrectly installed
or open.
TP13
Check your auxiliary
1.
Check capacitors Cl03, Cl04,
(Left
channel)
equipment and
Cl09, Cll9 and diode DlOl
i nput cables .
to make sure they are not
TP14
installed backward or
(Right channel)
interchanged.
2.
Check for solder bridges
w
.....
between two or more of the
IC socket pins. (This is
OK only if both pins are
on the same foil).
3.
IClOl installed backward
or shorted.
L