Light doesn't stay on when clock reaches actual alarm time

Had the same problem, pulled the plug on it yesterday and today it worked again, will be interesting to see for how long.

I’m having the exact same problem. Did you find any solution?

I have the same problem. Unplugged it for a half hour and plugged it back in and that fixed my glitch for 6 days, now it’s back. The light obviously still works for me and you since the lamp turns on pre-alarm.

I'm in the same boat now, I bought mine second hand about 5 months ago. It "soft locks" and none of the buttons are functional until it's unplugged, though they do make a sound like they're being pressed. Has anyone had any luck with a repair?

My issue kept happening more and more frequently (I think it got to daily). And then I just bought a new one.

Looks like my original lasted almost exactly 5 years. I couldn’t find a warranty of discount to get the second. I monitored the price on Amazon and got it for exactly $100 ($4 cheaper then I had years earlier).

My guess is that there is 4 years left on this new one.

Same problem. Disconnecting from the current does not help. I am looking for a solution to the problem through repair. I was surprised by the message about a speaker malfunction. The speaker works properly without distortion. I would be grateful for advice.

A SOLUTION IS HERE!

Same problem here. After alarm time is reached, lights goes off, display goes to maximum brightness. Disconnecting or performing the reset didn't help. As "professor" suggested, but was widely ignored, the problem turned out to be the speaker! (Although it was still working!)

Easy to test: remove one screw at the bottom, disconnect the speaker by pulling the small connector.

Now test the Alarm function. Light stays on at alarm time? Good!

Now connect anothet speaker and test again!

My 'defective' speake hat an Impedanz of only 3.2 Ohm. I replaced it with a 8 Ohm Speaker I had availabe.

Now the HF3520 works like a Charme again.

Good luck, wega

Okay, I'm an experienced tech engineer, and after reading the thread I see no solution and no good insight about the cause, so I tried to dive deeper with this issue and make some studies. First of all I've replaced the power supply and it didn't help.

Then, if you set up a new wake-up time right after the light fails to stay, for at least half an hour apart, it will work and stay for 1,5h after, then smoothly fades out. The most interesting thing if you set the wake-up time to the evening one, around 20.30 or something it still wakes and stays! But as for the morning time it fails. It's more likely for him to wake and stay if the brightness is less, as one of the guesses here says, you may "train" it at a lower brightness, but I need the brightest setting.

I tried to shift it's own clock for 12 hours, and set up two alarms, for 8.30 and 20.30. So the clock thinks it's morning when it's actually evening. And it still fails in the real morning and works and stays in the evening! Even with the brightness of 20.

The only significant difference between these conditions I can conclude is ambient lighting (it has the light sensor which lets it know how bright the display should be, and it's controlled with the CPU, so during the fail the display is bright), the sound sensor (it stops the sound if you make noise while it's singing), and the temperature in the room.