HU650 Radio - Slow to get FM audio

iamhives · Post by **iamhives** » 21 Apr 2019, 17:01

I'm having trouble with the HU650 in my 2006 V70 2.4NA. The problem is the fact that when turning the input to FM it sometimes takes a while for there to be sound. This does not occur on the CD input, radio only. It seems to take longer when the car is just started and less time if run for a while and then the car stopped and started again. Sometimes I have to turn the unit on and off several times. So far it has eventually always finally come on. Its almost as if a capacitor is taking a while to charge-up and which doesn't need to charge-up as much if previously run. I don't know if there is a capacitor to cause this but that's just what it seems like. I have previously changed the unit (because the previous one would never tune in an FM station) - but I don't think the current problem is (or is it?) related because this replacement radio has worked fine for the past 2 years. Any ideas?

While I'm asking about the radio, I also have no sound out of the drivers side rear speaker. I suspect the wiring but haven't had the time to remove the speaker to try and troubleshoot. Is this something that could be caused by the head-unit for is it likely the wiring to this speaker or the speaker itself?

537playing · Post by **537playing** » 21 Apr 2019, 17:12

I replaced my radio with a rebuilt one. It was randomly changing stations and bands. My rear speaker also has issues so I’m interested what others post on this.

EngineeringBloke · Post by **EngineeringBloke** » 21 Apr 2019, 17:32

Sorry, not sure about your slow radio issue, but with regard to the rear speakers...

Fazool wrote a post about Volvo stereo and it indicates the read door speakers are in parallel with the rear deck speakers. So do you have sound from the rear deck speakers - you may need to seat in the back seat to check, and set the fader to rear.

The rear door speakers are the same 6.5" 8-ohm full-range as the front door ones. These are wired in parallel to the 8-ohm rear deck speakers to create the 4-ohm impedance to each rear channel.

If the deck speakers are good, but rear door are not, then it is likely to be the rear door speaker or its wiring.

This is from:
viewtopic.php?f=33&t=43215

iamhives · Post by **iamhives** » 21 Apr 2019, 17:44

In my case it only the 2nd row drivers side speaker that is not working. The speakers near the rear hatch (V70) both work. If the V70 is like the S60 in the link with the 2nd row and deck/rear pillar wired in parallel it does suggest speaker or wiring. Can others confirm?

Post by **RickHaleParker** » 21 Apr 2019, 17:58

Sounds like a temperature sensitive component in the tuner. Goes out of spec when it is cooled off, goes back in spec after it gets warmed up.

iamhives · Post by **iamhives** » 22 Apr 2019, 06:46

Thanks, Yes, it does seem something like that hence my random guess along those lines of a capacitor - but obviously could be another component as you suggest. Almost every problem I've had with electronic equipment (from routers to DVD players etc etc) has been a bad capacitor. Any thoughts on how to identify the component? Since its only radio I assume that will help narrow in on the radio circuits. I'm pretty handy and fixed electronics before. Anyone know much about the internals of the HU650 before I just rip it apart to see if there is anything obvious like bad solder joints.

Post by **RickHaleParker** » 22 Apr 2019, 10:30

I use to keep a cylinder of cylinder of refrigerant under the bench for this. You chill the suspected components. When you get the right one, the radio would quit working. You can get Freeze Spray in a rattle can but it is expensive ~$1.20 - $1.50 per OZ.

iamhives · Post by **iamhives** » 22 Apr 2019, 12:08

The slight problem with this theory is that all was well over the winter in the cold weather and this only started happening the past few weeks as the weather warmed up. Doesn't rule it out obviously as it could be a coincidence but seems to make it slight less probable.

hanzbe420 · Post by **hanzbe420** » 20 Jan 2020, 06:45

There's actually A setting on the radio to scan for a better signal and its slow to turn on the music, but once its on its on. I'm not sure exactly what setting this is but its there.