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IC-775 DSP most common service | Radioaficion Ham Radio

IC-775 DSP most common service


Most Common Service Questions for the Icom IC-775 DSP

©1997 ICOM America, Inc.

Symptom: No TX output.
Probable Cause: Bad Q32 on RF unit.
Cure: Replace Q32 (2SC4673D) on RF unit. Also check for leaky D37 (MA862) on RF unit.

Symptom: Raspy RX audio when warm, sounds like intermodulation.
Probable Cause: Leaky D37 on RF unit.
Cure: Replace D37 (MA862).

Symptom: TX LED indicator does not light.
Probable Cause: R105 on SW-A unit has been knocked loose during shipping.
Cure: Replace or resolder R105 (1.8k)
Remarks: R105 is a surface-mount component.

Symptom: Harsh TX CW note.
Probable Cause: Unit needs factory update.
Cure: Change value of tantalum capacitor C18 on IF unit to 3.3uF, 16v.

Symptom: Radio is dead-does not power-up. Radio powers up if VCC line to PA is disconnected.
Probable Cause: Shorted PA FETs.
Cure: Replace PA FETs.

Symptom: Display dims in CW TX when AF volume is turned up.
Probable Cause: Unit requires factory update to logic unit.
Cure: Contact Icom Technical Support for update procedure.

Symptom: In new radio, rotary encoder shaft does not turn smoothly; feels rough.
Probable Causes: 1) Inadequate lubrication in rotary encoder. 2) Shipping damage to rotary encoder.
Cure: Replace rotary encoder.
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