Service manual

STP 11-25R13-SM-TG
3 - 22
Subject Area 2: REPAIR
REPAIR AN AUDIO TAPE RECORDER/REPRODUCER (ATR)
113-575-0046
Conditions: In a tactical or garrison environment, given a DA Form 2407 requirement for an ATR, dual-
trace oscilloscope with 10X test probes, multimeter with test leads, ATSG, audio amplifier, speakers,
demagnetizer, electronic equipment tool kit, soldering tool kit (light to medium duty), heat sink, audio
tapes (test, alignment, and blank), a known good ATR, bench stock, contact or tuner cleaner spray with
extension tube, manufacturers' manuals, and DA Pam 738-750.
Standards: The standards are met when repairs required for the ATR are identified and corrected.
Performance Steps
1. Review DA Form 2407.
2. Sectionalize the trouble to a defective stage.
a. Visually inspect for physical damage, missing controls, broken switches, broken wires or
connectors, hard or deteriorated rubber parts, and other discrepancies.
b. Operations check the ATR to verify that the deficiency or symptom exists and to what extent.
(1) Connect and turn ON the ATSG, audio amplifier, and speakers.
(2) PLAY a test tape and monitor the ATR meters for deflection and speakers for audible
sound.
(3) RECORD a 1 kHz tone from the ATSG on a blank tape and monitor the ATR meters for
deflection and speakers for audible sound.
(4) PLAY back the recorded 1 kHz tone and monitor the ATR meters for deflection and
speakers for audible sound.
(5) Test all front panel and remote control functions for proper operation.
3. Localize the trouble to a specific circuit by analyzing overall block diagrams and by performing
functional tests on suspected circuits.
a. Check for mechanical transport problems.
(1) No movement in PLAY or REC indicates that the capstan is not turning or not engaged.
NOTE: A hum from inside the transport indicates that the motor is not working.
(2) Tape eating indicates that the capstan is turning but the take-up reel is stationary or not
turning rapidly enough to take up the tape as it feeds from the capstan and pinch roller.
( a) If there was a tape-eating episode, remove the tape.
( b) If the pinch roller is not fully engaging against the capstan, the take-up reel may be
pulling the tape through without any speed control.
(3) Fast play could indicate a hard or deteriorated pinch roller.
(4) If FF and/or REW are inoperative or sluggish, assuming the motor is working, the driven
reel is not being powered at all or does not have sufficient torque to overcome the tape
friction. The driven reel alone must pull the tape through the transport.
NOTE: The required torque for the driven reel is much less for PLAY and REC as compared to FF and
REW as the capstan in contact with the pinch roller pulls the tape from the supply reel.
(5) Determine the cause for the driven reel and/or capstan to not turn.
( a) Look for a broken or stretched belt, or a deteriorated, dirty, or worn idler tire.
( b) Look for worn or broken parts; for example, a spring popped off an idler clutch or a
split press-fit gear or pulley.
( c) Gummed-up lubrication can prevent the idler gear or tire that operates the take-up
reel from engaging.
( d) For a solenoid that is not engaging properly, look for a weak spring, insufficient drive,
or lubrication problems.
NOTE: If the cause is not immediately evident, observe what happens when playing a work tape or run
the ATR with no tape present. Look for broken parts or bits of parts.