| Symptom: |
Low RX sensitivity on 2
meters. |
| Probable
Cause: |
Burned D6 diode on PA
unit. |
| Cure: |
Replace D6 diode
(MA862). |
|
|
| Symptom: |
No TX power output on
one or two HF bands. |
| Probable
Cause: |
Bad filter relay. |
| Cure: |
Locate and replace
faulty filter relay (will be type AHY-103) on the filter circuit
board. |
|
|
| Symptom: |
Low/distorted RX audio. |
| Probable
Cause: |
Burned SPE circuit
board trace on PLL unit. |
| Cure: |
Repair SPE (ground)
circuit trace on PLL unit. |
|
|
| Symptom: |
Low TX output on HF
& 6-meters. |
| Probable
Cause: |
Shorted D18 diode and
Q1 transistor in filter unit. |
| Cure: |
Replace D18 diode
(DAP222) and Q1 transistor (2SC4081). |
|
|
| Symptom: |
Low mic gain. |
| Cure: |
Install field
modification on main unit: Change value of R236 resistor from 27 k,
to 68k-82 k. The higher the resistor value, the greater increase in
mic gain. |
|
|
| Symptom: |
Thin-sounding mic
audio. |
| Cure: |
Install field mod
inside HM-103 microphone: Remove rubber gasket from beneath mic
element. |
|
|
| Symptom: |
Off frequency in FM TX.
Other modes OK. |
| Probable
Cause: |
FM VCO lock voltage
needs adjustment. |
| Cure: |
Adjust FM VCO lock
voltage for 1.5 volts as per service manual. |
|
|
| Symptom: |
Unit is stuck in TX
mode. |
| Probable
Cause: |
Shorted T/R switching
transistor. |
| Cure: |
Replace shorted Q32
transistor in main unit. |
|
|
| Symptom: |
Radio won't power up. |
| Probable
Cause: |
Burned ground circuit
trace in flex cable. |
| Cure: |
Replace flex cable EP2
at main board. |
