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Discussion Starter · #1 ·
My Denon 4800 A/V Receiver is having a problem in that the fans start running. With the receiver on, but nothing even playing, about once per minute, the fans ramp up and then turn off a couple of seconds later.


The fans are not supposed to run except when the thing overheats, which I would expect to only happen during loud playback. I don't even use the receiver's amps (I have external amps). I'm guessing that with nothing attached to the speaker terminals, there would be less power usage (due to open circuit instead of an 4-8 Ohm load). The ventilation around the system isn't too bad either.


I'm pretty sure it did not used to do this. I had been hearing this noise for awhile, but I thought it was the houses pipes or something. I just realized it was a noise coming from the receiver.


Have any Denon 4800 owners had the same issue? I think I might take the unit apart. Maybe the heat sinks aren't making good contact, which maybe is causing the unit's temp trips for the fan to go off or something. I have no idea. It is annoying though. When I bought the thing, I was leary about it having a fan.
 

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I had the fan turn on once. I was playing with the "Bass Mechanics" test CD and my new DIY subwoofer. I have had this unit for at least 4 years now and it has never come on before or after that day. There is definately an issue, have you felt the unit..is it hot? It could be a faulty temperature sensor.
 

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Discussion Starter · #3 ·
The unit was warm, but I don't know whether I would call it hot. If you put your hand on the top or the place on the back where the vent is for the fan to blow out (when fan is not on), then you could feel some warm air, but it wasn't really hot to your hand where it hurt to touch or anything.


When your fan did turn on that one time, did it turn on very briefly? Just spin up and spin back down?


I guess it could be a temperature sensor that has gone bad. It might not be hard to replace the temperature sensor if Denon would provide a part number. I also don't know whether one or both fans in the unit are spinning up (I think there are two). I also don't know whether it has an independent temperature sensor for each fan.


Thanks for the information.
 

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It came on for 10 to 15 seconds then turned off...certainly longer than spinning up then turning off. It was on the verge of hot to the touch, but the 4800 always runs a little warm...nowhere near as warm/hot as my Samsung TS-160. I really don't know if it has two fans, or where to look for the temperature sensor - sorry. I would email Denon and ask - I am assuming it is out of warranty now?
 

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I did not know my Denon 4800 had a fan until reading this thread. And I've used it every day I'm at home now for about 3 years.
 

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Quote:
Originally posted by rogo
I did not know my Denon 4800 had a fan until reading this thread. And I've used it every day I'm at home now for about 3 years.
Maybe yours doesn't work ;)
 

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Maybe it doesn't, but the receiver works. Every day I'm at home.
 

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Discussion Starter · #8 ·
I knew my Denon 4800 had a fan from reading reviews and the manual that came with it. However, I had never heard it before (don't know whether it had ever turned on or not) until several months ago when it started making this noise when not even playing a source. I didn't realize it was the fan until just a couple of days ago. It may be stupid, but the sound seemed like some sort of noise the house might make (water through pipes, some exhaust vent, whatever).


I'm going to play with it this weekend. Some ideas I have had:

- Maybe the heat sink is no longer making good contact to the processor ASIC. This would be easy to fix.

- The timing where this seems to have started somewhat matches when I switched from using the Denon's internal amps to using my external amps. I don't know exactly, because I never thought this had anything to do with my system. Maybe there is some issue with my unit and not using the internal amps. It should run cooler, but maybe there is some issue with my unit. I might try switching back to using the internal amps as a test.


I serioiusly doubt there are issues with the temperature sensors themselves. Those don't seem likely go out.
 

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Discussion Starter · #10 ·
Thanks Salvatore. It sounds like the same issue. I generally notice the problem after I have watched a movie or played music and eventually the unit is just still on (though not playing anything) while I'm doing something else and I notice the fan start cycling on and off. I bet Denon didn't do a good job of testing the AVR4800 with external power amps.


What did you end up doing about it? Do you just live with it cycling power on and off after a couple hours of use?


I wonder if an option would be to simulate having a speaker across the speaker terminals. A little wire and an 8-ohm resistor might do the trick. It might have to be a pretty high wattage resistor though.
 

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I just live with it. The fan doesn't make enough noise to bother me. And it only kicks in after watching more than one movie back-to-back, which I rarely do. Every once in a while though (usually when I need to raise cash for some other component upgrade) I think about selling off the external amps and going back to the internal ones.
 
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