Bringing this thread back ...
Had hoped to go do some HF radio operating this weekend, decent conditions on 20m for a change and it's been forever since I operated. Of course, I don't have any luck... I'm driving along - I decided I wanted to check if the 6.35mm to 3.5mm adapter I was using was a mono adapter or stereo adapter - so I pulled it out, only not all of it came out. Half of it got stuck in the socket. Got bits of it out but in the end couldn't get it all. No audio out of the front speaker as the radio thought there was still a set of headphones plugged in.
Removed the entire socket but left the PCB in place, just without the socket on it - turns out the headphone "sense" switch in the socket is
open when you have the jack plugged in and as such is also open when you remove the socket - so still no audio. Best I can tell the switch pulls the signal to ground when closed, which then causes the output of an inverter somewhere downstream to go high which then switches the audio over to the front speaker/external speaker jack. Admittedly I'm not much of an EE, so I may be wrong. The schematic is, for the most part, way over my head...
Schematic for anyone interested:
https://1drv.ms/b/s!AiTfbZIDObJKpHzl-16wJ9T6k2tO
Phone Board is on page 2, near the middle... Anyway...
Fortunately the service manual has all of the parts listed with both the manufacturer and Icom P/Ns. Unfortunately the only people that have that part are Icom in Japan and some new-old electronics seller on eBay based out of the UK (that really took some digging to find, didn't even have the P/N listed on that one). We'll see where this goes... I may resort to shorting out the headphone sense pads on the connector PCB and then use the external speaker output on the back for my headphones instead - pending a quote from Icom on a replacement part.
/Rant