ADJUSTMENT PROCEDURE
PCB BS 398
Denomination: Tuner IF video/IF audio
Adjustment procedure for IF section
Instruments used:- 0 to 30V adjustable power supply.
- 0 to 12V adjustable power supply.
- 12.6~ - 200 mA power supply.
- Sweep generator, >lO MHz and
markers at: 31.5, 33.5, 35.1.
36.5, 39.5, 41.5 and 37.1125 MHz
for adjustment of output filter.
- Dual trace oscilloscope - 10 MHz
pass-band.
IF signal (video carrier
39.5 MHz and audio carrier
33.5 MHz) with 100% standard
video modulation, bar modulating
signal, 20% white level - 76%
black level.
Audio carrier modulated at 1 kHz
with + 50 kHz of deviation at
50 /us of preemphasis.
- Voltmeter (15V setting).
Note: See legend of test points (TP) at the end of adjustment procedure.
Preliminary operations:
- Supply the p.c.b. with 12.6V at terminal A 9.
- Adjust the varicap voltage to 26V (terminal B 1).
- Position the wipers of P 1 and P 2 towards earth so as to have
connected the maximum resistance.
.
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ACEC
