| Troubleshooting Guides: IC-820H |
| Symptom: |
Intermittent/no RX/TX.
Display reads "_______". |
| Probable
Cause: |
PLL unlock. |
| Cure: |
Replace bad X1 crystal
oscillator on PLL unit. |
|
|
| Symptom: |
Some front panel
controls on left side do not work (mode switch, lock switch, etc). |
| Cure: |
Rework bad or cracked
solder at J1 connector on SW-A unit. |
|
|
| Symptom: |
Unit stuck in TX mode. |
| Cure: |
Replace bad Q40
transistor on main unit. |
|
| IC-2340H |
| Symptom: |
Any of the following:
Cannot change band to UHF, no UHF volume or squelch control, no UHF
tuning, or strange-sounding beep tone. |
| Cure: |
Rework bad soldering at
J3 connector on display unit and replace the SW-B board with a
factory-modified flex PC board. |
|
|
| Symptom: |
No audio output from
receiver. |
| Cure: |
Remove excessive solder
on the Main-A unit near the audio amp. |
|
|
| Symptom: |
Howling if volume is
turned up when using UHF. |
| Probable
Cause: |
Microphonics in VCO
section. |
| Cure: |
Resolder the ground
spring at the UHF VCO shield. You may also add a second spring for
further improved resistance to microphonics. |
|
| IC-2700H |
| Symptom: |
On the control head,
cannot change bands on either VHF or UHF, no volume or squelch
control, or no tuning control. Microphone control OK from mic. |
| Probable
Cause: |
Cracked solder
connections on the SMD connectors between the front panel controls
and the display board. |
| Cure: |
Repair bad soldering at
J3 and J4 connectors on the control unit and/or J1 connector on the
SW-A and SW-B units. |
|
|
| Symptom: |
No transmit on either
band. |
| Probable
Cause: |
Cracked solder
connections on the SMD connectors between the microphone connector
board and the logic board. |
| Cure: |
Rework bad solder at J4
connector on logic unit and/or J2 connector on mic unit. |
|
|
| Symptom: |
No audio output from
receiver. |
| Cure: |
Rework bad soldering at
the EXT SPKR jack on the Main-A unit. |
|
| IC-281H |
| Symptom: |
Cannot turn on or off,
no volume control, no tuning control. |
| Probable
Cause: |
Cracked solder
connections on the connectors between the front panel control pots
and the circuit board. |
| Cure: |
Repair bad soldering at
J4 and J5 connector in logic unit and/or J1 connector on SW-A and
SW-B unit. Replace SW-A and SW-B unit with factory-modified flex PC
boards. |
|
| IC-RP1520/1620 |
| Symptom: |
Weak RX, sometimes
weakness varies. Alignment does not help. |
| Probable
Cause: |
Leaky tantalum
capacitor. |
| Cure: |
C80 tantalum capacitor
(1 µF, 35 V) on the receiver unit may be installed backwards. The
PCB silk-screening is incorrect. Replace the capacitor with a new
one. |
|
| IC-970A/H |
| Symptom: |
No RX/TX on 440 MHz
band. Dashed lines on display. |
| Probable
Cause: |
PLL unlock. |
| Cure: |
LPL loop on the PLL-B
unit is out of alignment and/or unstable. Replace the plastic
trimmer capacitor with a ceramic 12 pF trimmer capacitor and
realign. |
|
|
| Symptom: |
Extremely low or no TX
power output. |
| Probable
Cause: |
Broken solder
connection at J2 connector on APC board. |
| Cure: |
Repair solder
connections. Reposition APC board upward to reduce stress on
connector to prevent future failure. |
|
