Section II. REPAIR AND TESTING

TM 11-6625-922-15

Note.

d. In all tests, the possibility of intermittent troubles

Test

equipment

required

for

should not be overlooked. If present, this type of trouble

often may be made to appear by tapping or jarring the

maintenance of the TS-2669/GCM are

equipment.

listed in appendix C of this manual.

Section II. REPAIR AND TESTING

6-4. Removal and Replacement Procedures

printed wiring assemblies if any component is replaced

(fig. 9-36)

during repair. These adjustments are to be made before

performing the calibration procedure in paragraph 6-7.

a. Removal of Vfo Assembly C4713. Remove

bottom cover from TS-2669/GCM. Loosen but do not

a. 2-MHz Oscillator and Amplifier Assembly A4.

remove 12 front panel mounting screws (2). Remove

Use Oscilloscope AN/USM-182, connected by a low-

front panel knobs (6). Remove four mounting screws

capacitance probe (10pF) to TP1, adjust L2 and L3 for

(1). Disconnect both connectors on C2713 and carefully

maximum amplitude at TP1.

remove assembly from bottom of TS-2669/GCM.

b. 2-MHz Modulator-Mixer Assembly A14. Operate

b. Removal

Frequency

Counter-Display

RANGE (KHZ) switch to 50- 600, TRANSMIT

Assembly C4625. Remove top cover from TS-2669/

FREQUENCY-RECEIVE FREQUENCY switch to

GCM.

Disconnect three connectors from C4625.

TRANSMIT FREQUENCY, CARRIER FREQUENCY

Remove six screws (3). Remove escutcheon (4) and

control to 100-kHz output frequency, and TRANSMIT

radio-frequency interference (rfi) window (.5) from front

LEVEL DBM control fully cw. Using Oscilloscope

panel. Lift C4625 assembly carefully up and out of TS-

AN/USM-182 connected to TP1 on the 2-MHz

2669/GCM.

modulator-mixer assembly (A14), adjust L1 and L4 for

maximum amplitude at TP1.

Using Voltmeter,

c. Parts Removal. Before a part is removed, note

Electronic ME-30E/U connected to terminal K of A14

the position of the part and its leads. Wire replacement

(use extender board A19 to facilitate connection to

parts in essentially the same position to avoid undesired

terminals), select R62 to provide a level at terminal K of

coupling or other effects. In the case of printed circuit

0.0775 volt + 1 percent.

cards, always be sure they are replaced in the proper

connector in the original orientation, so that the

c. 200-kHz Modulator-Mixer Assembly A15.

component side of the board faces the correction

Operate the RANGE (KHZ) switch to .1-50, TRANSMIT

direction. Follow the instructions in TB SIG 222 for the

FREQUENCY-RECEIVE FREQUENCY switch to

correct procedures.

TRANSMIT FREQUENCY CARRIER FREQUENCY

control to 10 kHz output frequency, and TRANSMIT

LEVEL DBM control fully cw. Using Oscilloscope

6-5. Repair Procedures

AN/USM-182 connected to TP1 on the 200-kHz

a. All components of the printed circuit card have

modulator-mixer assembly (A15), adjust L1 and L4 for

been conformally coated; therefore, it is necessary to

maximum amplitude at TP1.

Using Voltmeter,

peel back the coating before any repairs can be made.

Electronic ME-30E/U connected to terminal L of A15

b. Use pencil-type soldering iron with a 40-watt

(use card extender A19 to facilitate connection to

maximum capacity, because the circuitry is

terminal), select R62 to provide a level at terminal L of

transistorized. If the soldering iron is used with ac, use

0.0775 volt 1 percent.

an isolating transformer between the iron and the line.

d. Low-Pass Active Filter Assembly A13 Only.

Do not use a soldering gun; damaging voltages can be

induced in components.

(1) Use card extender A19 to make

components on low-pass active filter assembly A13

Note.

accessible.

Connect probe from channel A of

Do not replace the conformal coating

Oscilloscope AN/USM-182 to terminal P of A13 and

on the assembly until after it has

probe from channel B to terminal Y of A13. Operate

been tested and determined to be

MODULATION FREQUENCY HZ switch to 25. Check

electrically correct.

to see that the waveform on channel A is a square wave

c. After a component has been replaced on a

and the waveform at channel B is a sine wave. Adjust

printed circuit card, recoat the affected area with an

the AN/USM-182 so that both channels are displayed

acceptable coating material.

simultaneously and are ac-coupled. Superimpose the

sine-wave pattern on the square-wave pattern so that

6-6. Adjustments After Repair

their

The following adjustments are to be performed on the

6-2