Most Common Service Questions for the Icom R-71A Receiver
The information on this page is subject to the
terms and conditions set forth on the ICOM America
Service FAQ Index page.
Symptom:
Radio is dead; no display, no lights. Problem may intermittent.
Probable
Causes:
1) Cracked solder on regulator unit. 2) Loose board mounting screw
on the regulator unit. (that provides ground to the board) 3) Cracked
joint(s) where power transformer mounts to regulator unit.
Cure:
Remove the regulator unit from the radio and resolder all suspicious
joints on the regulator unit. Pay particular attention to the joints at
heat sink-mounted transistor Q1 on the regulator unit. Modification:
After tightening the regulator unit to the chassis, at the chrome screw
with the spacer, apply a solder bridge across the spacer to form a
solid electrical connection between the board and the chassis. This
will prevent future failures due to bad connections at this joint.
Remarks:
The power supply on the R-71A receiver runs very hot, and problems
with the regulator unit are common. We recommend inspecting and
servicing (if needed) the regulator unit in all R-71A receivers that
come in for repair.
Symptom:
AC hum in audio; radio may seem to vibrate during operation; pilot
lamp may be dim. Inspection reveals excessive AC ripple on 13.8 line
in radio.
Probable
Causes:
Bad bridge rectifier bridge D1 on regulator unit.
Cure:
Replace bad D1 (KBPC102). Service regulator as per previous cure.
Symptom:
AC hum in audio after CR-64 is installed.
Probable
Causes:
The oven in the CR-64 is drawing more current than the reg. unit can
handle.
Cure:
Service the power supply as listed above. On older production units,
check resistor R2 on the reg. unit. If it is 100 ohms, replace it with a
56 ohm, 5 watt. Adjust the reg. unit output voltage to 13.6 volts.
Symptom:
No audio. S-meter fully deflected.
Probable
Causes:
-10 volt DC-DC converter failure.
Cure:
Replace faulty DP-2 module (IC-6) on the matrix unit.
Symptom:
Frequency display blanks out periodically with only decimal points
remaining.
R-71A
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