Adcom GTP 500 II Service Manual

Page 1

SERVICE MANUAL

ADCOM®

TUNER/PREAMP
GTP-SOOH

TABLE OF CONTENTS
Alignment ............................. 1
Chassis Layout ........................ 2
Wiring Diagram ........... . ........... 3
Service Parts List ..................... 4
Specifications ......................... 12
Typical Performance Data ............. 14
Printed Circuit Boards ................. 16
Schematic Diagrams .................. 18

ADCOM'

TECHNICAL SERVICE DEPARTMENT
11 ELKINS ROAD
EAST BRUNSWICK, NJ 08816
TELEPHONE (90') SUI-1130
FAX (903) 390-9152

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FM IF and HF Alignment / FM MPX Alignment GTP-500ll

Instruments: FM Stereo Signal Generator (400Hz. Modulated @ 100%). THD Analyzer. Oscilloscope. AC Voltmeter.
Digital DC Voltmeter
Connections: THD Analyzer, Oscilloscope and AC Voltrneter to audio outputs (LEFT 0r RIGHT as necessary).

Generator Tuning Dial
Step . Setting Adjust Adiust for
Coupling Frequency
1 875MHz L107 3V reading. i 0.1V. on
Dc Voltmeter across TPS & TP4
Not Necessary
23V reading, 1 0.2V, on
2 OBMHZ C. 04 DC voltmeter across TPS 8t TP4
3 Repeat steps 1 and 2 until no lunher improvement is observed.
Maximum reading on
4 90MH2 90MH2 L102, L103. L104 AC V oltm el er
Antenna terminal, . .
5 input below 105MHz 105MHz 0 0" Maxmu" readmg °"
limiting oi IF CT102, CT103 AC Voltmeter
Maximum output.
5 saw: 98MHz L106 minimum distonion
7 Repeat steps 4, 5 and 6 until no further improvement is obsewed. [MUTING OFF]
8 L151W 0.000V. iomav, on DC Voltmeter
Antenna terminal connected across TPt &TP2
1mV in ut 90MHz SOMHZ _ , ~~~~~~~~
p L151 B Minimum reading on THD
9 t , Analyzer
0 Repeat steps 8 and 9 until no further improvement is obsenred. (MUTING OFF]
Antenna terminal Muting level
' 90MHZ QOMHz VR 151
" 15uV input [MUTING oul
Antenna terminal. 90W VR 152 SIGNAL LEVEL INDICATOR
2 1mv input SOMHZ 1 5m LED ON
1 a Amenna terminal. 93MH1 Pllot@10%. ssMHz VR 301 Best separation MUTING ON.
imV input [L or Ft] 1kH1 @ 90% mod. HI BLEND OFF
AM IF and RF Alignment

Instruments: AM Signal Generator [400l-lz, Modulated @ 30%), AC Voltmeter. Oscilloscope. DC Voltmeter,
Connections: AC Voltmeter and Oscilloscope to audio outputs (LEFT or RIGHT).

Generator Tuning Dial
Ste - ' '
P Coupling Frequency smug Adjust Adjust tor
1 530kHz L203 (N, i 0.1V, on
WWW, m,t Necessary l531kHzl Eurons oc Voltrneter across 193 & TN
2 1600kH2 CT202 25V, 1 0.2V, on
(1602kHz) Europe DC Voltmeter across TP3 & TP4
3 Repeat steps 1 and 2 until no further improvement is observed.
4 Use Test Loop 450kHz 530kHz L206
Use Test Loo . Maximum reading
5 Raw sign; scout: SOOkHz L202. L204 on Ac yams.
into loop antenna,
6 2mV input level 1400 kHz MOOkHz CT201
7 Repeat steps 5 and 6 until no further improvement is observed.
Use Test Loop NWWWWWWWMW
Radiate signal
8 in, loop Manna. 1ODOkHz lOOOkHz vnzm 3'6 NALerEE'El'gBICATOR
5mV input level