Dudes, the FM thingy has been known to be a problem since forever. Usually there is a chip both inside the HU650 and HU850 that goes bad(implicated), it is the FM receiver/DSP chip SAA7709. It is implicated to go bad leaving you without FM radio OR crackling/popping sound that comes and goes.(does not affect CD, AM whatever else)

However it is indeed possible for the antennas to go bad too or have a loose connection. There are two for multipath diversity. One in rear bumper and one around rear windshield. Also, either both or one of them has internal power circuitry to boost the signal(power comes from HU unit), that can also fail.

So you have THREE possible sources for the no FM situation. For instance I also have no FM radio but it comes back when the car/radio heats up sufficiently and goes away if I use the AC and the car is cooled off. When it starts to cut out/crackle I know its either coming back or going away.
Mind you I use a bluetooth fm dongle. But I've also recently noticed that it also cuts out if I am in a region with shoddy FM reception(while still using my fm dongle)

It is a really complex problem that no one has found a cure-all fix. Some replace the antenna and have it working, other guys replace the SAA DSP chip and also get it working, other people have no success with either and end up replacing the entire unit which works for a year or so before the unit exhibits the same issues.

But don't take my word for it

https://www.matthewsvolvosite.com/fo...ic.php?t=97129
https://www.volvoforums.org.uk/showthread.php?t=275636
https://www.elektroda.pl/rtvforum/topic3718989.html (non-english but you can use google translate)

ah well in that case is there any point?

could i get DAB? and where would the antenna go? (as in i would need a replacement unit anyway)

most new units have DAB, yes, ideally you'd want the aerial as far away from the engine as possible, mine is stuck on the B post right at the top, it's not really noticeable

to be honest though I more or less gave up on it because as you drive around it tends to cut out and when that happens (on mine anyway) it skips to the FM version which still needs the aerial to be functional on yours obviously and there's a bit of a delay and it ruins the song. so more often than not I just use FM

plus side though you'd have bluetooth and just make a nice long playlist, set to shuffle and it just comes on when you turn the car on with your phone in your pocket

Up to you to decide. I talked with a guy who only repairs Volvo modules and he said out of 10 such HU650/850 he managed to revive 5. The rest still exhibited cracking/cutting out despite reflowing/replacing the DSP processor.

I googled a lot on the problem and have seen other people who had theirs fixed with a reflow, but the fix lasted only 6 months or a year. Internally these units get VERY hot. Mine had visible darkening/discoloration of the PCB and cracked solder joints implying a lot of heat, much more than should be there. Maybe if repaired, a small fan should be installed permanently inside to not allow it to get so hot.

yeah i dont want to invest in something to only worry it fail again.

as it is now i have a radio that only operates AM
but i have the bluetooth adapter in the back with the mic so i can use my phone for entertainment which is fine.

bigger fish i guess :)

thanks for the info everyone!