so this has been driving me nuts for about two weeks now. my IC-7300 started acting up where the receive audio is just really thin and quiet, like im hearing through a tin can kind of thing. already pulled the internal speaker and swapped in a known good one and no change so its not the speaker itself.

the weird part is that if i plug headphones in the audio sounds completely normal, good volume, full tone, no issues at all. its specifically the internal speaker path that seems messed up. i went into the menu and checked all the audio settings, nothing looks out of place, the AF gain is responding but just the overall level is way down compared to what it used to be.

im wondering if maybe the amp stage driving the internal speaker has a bad component, maybe a cap or something on that board. i do have a service manual but honestly the schematic is pretty dense and ive been hesitant to dig in. has anyone seen this specific failure on a 7300 or know which part of the board to look at first? i dont really want to ship it to icom unless i absolutely have to.

yeah that headphone vs speaker difference is actually a pretty useful clue. on most of these rigs the headphone jack has a switch contact that routes audio away from the internal amp when something is plugged in, so the fact that headphones work fine rules out everything upstream of that switching point. means the problem is almost certainly in the driver stage for the internal speaker specifically.

on the 7300 there's a small audio amp IC that handles the speaker output, i think it's somewhere around the main unit board but you'd want to confirm with the service manual. before you go poking around though id check the obvious stuff first - look for any caps in that stage that might have bulged or leaked, i've seen cheap electrolytics go bad on otherwise solid rigs. also worth checking the solder joints around that amp IC, reflow if anything looks even slightly cold. the 7300 runs warm and thermal cycling can crack joints over time.

if you have a signal tracer or even just an audio probe (resistor and cap in series with a set of headphones) you can trace the signal from the input of that stage through to the output and figure out pretty quickly where it's dropping off. saves a lot of guesswork.

had something similar on my 746 a while back, not the same radio i know but same basic idea. turned out to be a dried out electrolytic on the output of the speaker amp, thing measured fine on a basic DMM but under any load it was just collapsing. had to actually test it in-circuit with an ESR meter to catch it. might be worth checking that if you have one, those cheap little ESR meters are honestly worth keeping around for exactly this kind of thing.