Dreaded HU-650 intermittent FM and possible fixes?

[cmayo1]

Well, if you're ever looking to work together on something, I've got my HU-650 fully disassembled. I have no idea what I'm doing, but I'll buy some simple tools if you'd like to continue down this project with your used one.

I'd like to mention that mine, when it doesn't play anything, it also doesn't pick up any channels. The one thing I don't understand is why it doesn't make any sort of feedback noise. If the antennas were working, it would be making some sort of noise, unless the connection to the antenna was lost somewhere along the way. If there are two antennas, I can't imagine that both break at the same time. From what you're saying, it sounds like one of the antennas feeds the other one for power? Has anyone had any luck swapping the two antennas, or are they not identical?

At least for mine, I have a hard doubt that it's the antennas, because CDs seem to make no difference. If FM doesnt work, CDs don't work either. Maybe that's just my own problem. Have you tried CDs with yours when you know the FM wasn't working? I know you've swapped yours for a used one; just some curious questions

[dikidera]

I am fairly certain it is the unit. Mine had intermittent loss of channel too. Sometimes it would search endlessly for a channel for like 10+ minutes and wouldnt find one. After I replaced the unit, it all worked flawlessly.

There are too many things inside that can go bad in these units. All the electrolytic capacitors need to be replaced(since some are at fault here) with the same values. Then you will find some resistors have cracked solder. The main DSP chip SAA7708 is also implicated to be bad by many different forums.

Since I disassembled this unit too many times I simply left out the CD out of the unit, I never used it. But I can tell you only AM radio worked for me.

[cmayo1]

I'll probably end up replacing mine with a used one. I'd go aftermarket, but it doesn't feel right. I'd rather go stock and know something works well with the speakers than investing in something that doesn't turn out well in the end.