Icom IC-736 Faq

Most Common Service Questions for the Icom IC-736 & IC-738
The information on this page is subject to the
Unless otherwise noted, the following service questions apply to both models.
Symptom:
Probable
Cause:
Cure:
Symptom:
Probable
Causes:
Cure:
Remarks:
Symptom:
Probable
Cause:
Cure:
Symptom:
Probable
Cause:
Cure:
Service FAQ Index page.
Frequency jump in LSB after changing modes.
LSB BFO is not being switched properly by logic; unit may need
factory update.
With radio turned off, measure resistance of pin 17 to ground on IC24
on main unit. Should be 47k. If it measures above one meg-ohm,
install a 47k, 1/8 resistor over the top of IC24 between pins 10 and
17.
Radio is off frequency.
Reference oscillator needs alignment.
Field: First reset CPU to clear all BFO presets, then tune in WWV
and align L29 on PLL unit for zero beat in USB mode. Shop: Reset
CPU. Align L29 for 60.0 MHz at P2. Check alignment of BFO.
Before performing this alignment, make sure that update to prevent
LSB frequency jump has already been installed in radio (see above
cure).
In IC-736, TX SSB audio sounds harsh. Average talk power seems
low.
Driver and PA idle current is set too low.
Realign idle current as per procedure on page 5-8 of the service
manual with a change in specs: Adjust R8 for a 300mA increase and
R44 for a 500mA increase. Total idle current draw should be about
1000mA(1A).
In IC-736, unit will not turn on. Unit powers up if VCC cable is
disconnected from PA.
Shorted driver and PA FETs.
Replace driver and PA FETs. Inspect PA unit for overheated
components and replace as necessary. Re-align idle current after
repairs as per new spec. (see above)
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