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Author Topic: IC-756PRO low audio during warm-up  (Read 106 times)

AA4PB

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IC-756PRO low audio during warm-up
« on: March 22, 2023, 11:13:13 AM »

My IC-756PRO has low audio levels (speaker, ACC1 output, ACC1 tx input, microphone) which gradually increase until warm-up of about 30 minutes. After that period of time everything seems to be normal. Because it is all audio in/out I'm suspecting perhaps a reference voltage regulator feeding the D/A converters on the DSP board. Has anyone else experienced this? What was your solution?
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Bob  AA4PB
Garrisonville, VA

N0GV

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Re: IC-756PRO low audio during warm-up
« Reply #1 on: March 22, 2023, 11:58:47 AM »

I have not ever dealt with the unit myself but on general principles I would look at the reference voltage circuit. Either a resistor is way out of spec or a capacitor is leaking....

Good luck!

Grover
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W9IQ

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Re: IC-756PRO low audio during warm-up
« Reply #2 on: March 22, 2023, 12:49:03 PM »

My IC-756PRO has low audio levels (speaker, ACC1 output, ACC1 tx input, microphone) which gradually increase until warm-up of about 30 minutes. After that period of time everything seems to be normal. Because it is all audio in/out I'm suspecting perhaps a reference voltage regulator feeding the D/A converters on the DSP board. Has anyone else experienced this? What was your solution?

Scope the input to the audio amplifier section (DRAF out of the DSP board) to isolate the source of the problem. I would be skeptical of a Vref problem.

- Glenn W9IQ
« Last Edit: March 22, 2023, 12:57:29 PM by W9IQ »
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.
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