B&K 415 - Page 76

Preliminary:
Bias Supply:
Oscilloscope:
Signal Gen.:
PHILCO-FORD "S" LINE TELEVISION RECEIVER
VIDEO IF AM AND SWEEP ALIGNMENT PROCEDURE - ALL CHASSIS
A.
B.
C.
D.
E.
F.
The following video IF alignment is based upon a tuner with proper bandpass alignment con•
nected to the TV chassis.
Disable horizontal sweep section by opening jumper from cathode of horizontal output tube
6KD6 pin
#2 to ground and place "Normal/Service" switch in "Service" position.
Preset VR! sound rejection pot. and VR2 AGC distribution pot. to approx.¼ turn CW.
Apply approx. 10.5VDC to M4 (AGC) and adjust for 2.2VDC at M9 (Tuner AGC). Adjust VR2
(AGC) for 6.0VDC at IF AGC T.P. (Test Point).
Connect in series with lOK resistor to 2nd detector output lug Ml4 on VIF panel (P2).
Connect in series with test jig to tuner UHF input (J2T). Set channel selector to UHF.
AM ALIGNMENT CHART
STEP
SIGNAL GEN.
ADJUST
REMARKS
30% MOD.
1
44.0MHZ
L6 {&OTTOM) FOR WAX. PEAK L.,6 (BOTTOM). l.9, L10, & L.13 AT THEIR RESPECTIVE
F'REQUENCIES F°OR MAXIMUM DEFLECTION ON SCOPE. USE PEA.K WITH
2
44.0MHZ
L9 & L10 FOR t-AAX. CORE NEAREST TOP OF' COIL. ADJUST SIGNAL GENERATOR INPUT AS
NECESSARY TO MAINTAIN l ,OV P/P ON SCOPE.
3
42. 75MHZ L 13 FOR MAX,
4
45,SMHZ
CIT
FOR MAX. (ON TUNER)
PEAK L 1T AT 45.5MHz. ADJUST SIGNAL GENERATOR INPUT AS
NECESSARY
FOR 1,0V P/P ON SCOPE'., PEAK L.1T WITH CORE AT TOP
uF COIL.
5
41
.25MHZ
L6 (TvP) F'OR MIN.
ADJUST L6
{TOP) ANO VA 1 IN THAT ORDER F'OR M1NIMUM DEFLECTION
ON SCOPE. INCREASE SCOPE GAIN IF NECESSARY F'OR SUFFIClENT
6
41 . 25MHZ
YR\
F'OR MIN •
INDICATION. REPEAT STEPS 5 ANO 6. ADJUST L12 FOR MINIMUM
OEFLECTION. AOJUST L11 ANO L14
IN THAT ORDER FOR MINIMUM
7
38. 75MHz
L 12 FOR MIN. (TRAP)
OEF'LECTION. INCREASE SCOPE GAIN If' NECESSARY FOR SUFFICIENT
INDICATION.
REPEAT STEP 8. KEEP ALL CORES AT COIL END AWAY
8
47.25MHZ
L 1t ANO L 14 FOR MIN. (TRAPS I
FROM
BOARD.
CAUTION!
REMOVE AM GENERATOR FROM J2T BEFORE PRO~EEO!NG WITH SWEEP ALIGNMENT.
NOTE: TO PROPERLY POSl'1'10N FINE TUNING FOR SWEEP ALIGNMENT. SET TUNER TO CHANNEL 4 ANO INJECT 65.7SMHZ 30% MODULATED AT ANTENNA
TERMINALS. ADJUST
F°INE TUNING CONTROL FOR MINIMUM SCOP( INDICATION. DO NOT TOUCH FINE TUNING OR CHANNEL SELECTOR F'OR BALANCE
OF' ALIGNMENT.
SWEEP GEN.: G. CONNECT IN SERIES W1TH MATCHING NETWORK TO VHF' TUNER A.NT. INPUT. (SEE FIGURE 9 FOR NETWORKS)
SIGNAL GEN,: H. LIGHTLY COUPLE TO LUG M:16 (ON P2) OR SWEEP GEN. OUTPUT CABLE TO PROVIDE MARKERS.
STEP
9
10
11
SWEEP SIGNAL
ADJUST
GEN.
GEN.
40-SOMHZ
42,17MHz
C 13
(1-F')
4!5.75MHZ
Lt T (ON TUNER)
40·50MHZ
42.17MHZ
c9
(l•F') 4!5. 75MHZ
OBTAIN FRINGE CURVE AS FOLLOWS
....
..
REMOVE BIAS FROM M4: (APPLY SLIGHT
LOWER SWEEP INPUT TO MAINTAIN 1.0V
COftRECT REPEAT STEPS 1 THROUGH
1 o.
MEASURE
2.2YDC
TUNER ACC
SWEEP ALIGNMENT CHART
REMARKS
SET SWEEP FOR 1.ov p/p ON SCOPE. ADJUST ,oR MAXIMUM GAIN AND RESPONSE F'IG.
16A. ADJUST SWEEP INPUT TO MAlNTAIN 1.ov p/p ON SCOPE:. L13 ADJUSTS 42.17MHz
MARKER AND L1T AOJUSTS 45,7!5MHZ MARKER. ADJUST LSI TO TILT FOR FLAT RESPONSE.
IF' L9 DOES NOT GIVE f'LAT RESPONSE. LG (BOTTOM) CORE MAY BE ADJUSTED FOR F'LAT
RESPONSE:. IF' 1.,6 IS ADJUSTED REPEAT STEPS 5 AND 6 IN "AM ALIGNMENT_,. PROCEDURE.
••oo NOT TOUCH L.10.··
BIAS tf' NECESSARY TO REMOVE NOISE LEVEL INTERFERENCE},
P/P SCOPE DE:F'LECTION, RESPONSE F'IGo 108 SHOULD BE OBTAINED. IF' FIG. 168 IS NOT
s
SCOPE
TO
SWEEP
GEN.
~,¾---
:s: ,o,
? 10'11.- 0.,~.lt ;_70'1'. ¥.I.LL('
I ,o,.. - "'II, ,o.,. .. u.
: •O"t. - ·:~i;. .~.,.
:: 20"11, -4L67U ·,t
O'll .. ,LL I~
(~"""GI "[$#'00,Sll
••. o ...
Figure 16, Video IF AM & Sweep Alignment and Response Curves
SECTION
Courtesy of Philco-Ford Corporation
74
I