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Pete
Pete, Computer Enthusiast
Category: Computer
Satisfied Customers: 18565
Experience:  Over 16 years of experience in the Electronics and IT industries.
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I have denon avr 2802 I bought on ebay about 2 months ago.

Resolved Question:

I have denon avr 2802 I bought on ebay about 2 months ago. It worked when i tried it out with a mixture of speakers connected direct for surround and centre and pre outs into active SW and front pair. I came back to it yesterday and connected up all direct speakers- no pre outs apart form the SW and could not get any sound. As before i have plugged my ipod via 3.5mm to RCA into 'CD' (also tried others) I have since tried just with headphones (and ipod). Have reset microprocessor a few times. Any ideas. R XXXXXX

Submitted: 3 years ago.
Category: Computer
Expert:  Pete replied 3 years ago.
Pete :

Hi there,

Pete :

Can you hear any sound when the speakers are disconnected and only headphones are connected?

JACUSTOMER-de78jgkw- :

No sound with spkrs disconnected and only headphones connected

Pete :

Ok, then that rules out a speaker wiring fault.

Pete :

The problem is internal within the Denon, most likely in the audio processing part of the circuitry.

Pete :

Do you know approximately how old it is?

JACUSTOMER-de78jgkw- :

It's pre HDMI connectionjs. about 9 years. Howvere as I said it did work when I first tried it about 2 months ago and it was when I came back to it yesterday that I couldnt get it to work..

Pete :

On older units, they usually suffer from gradual intermittent failure first, before it becomes more permanent.

Pete :

So the unit may have been starting to show signs of a problem before it was sold on.

Pete :

You can try resetting the microprocessor 4 or 5 times in a row - it might get it working for a short while.

Pete :

However to get it working long term, it will need some detailed diagnostic testing at a Denon lab.

Pete :

If you have some experience in electronic repairs, you could have a look inside for any obvious signs of burned capacitors, bad solder joints, or swollen capacitors.

Pete :

If the fault is not visually obvious then thorough testing will be the only way to get to the bottom of it.

JACUSTOMER-de78jgkw- :

I don't buy that. It worked fine two months ago. Been safely stored since . I have also reset the micoprocessor several times (4 or 5 times). Gradual I might accept but fine--to-nothing I can't. Output transistors don't go when switched off for 2 months. I wondered if the ipod connected to Cd was the right socket and if not could that have causd damage?

Pete :

Connecting the iPod to the wrong input socket would not cause any damage.

Pete :

Are you able to check inside for any faulty components, or attach a photo here of the inside so I may check?

Pete :

One other thing - when you connect the headphones, does the display change to show the action?

Pete :

And when the headphones are disconnected, does the screen change again?

JACUSTOMER-de78jgkw- :

I had a look yesterday after trying it for an hour unuccessfully.No melted capacitors or cracked or melted pcbs.etc. I wondered how to test the the output transformer but of course that is not used for headphones. I'll have another look but to take a useful photograph requires taking to bits to expose the underside of the pcbs

Pete :

Just going back to the microprocessor again, how many times was it reset?

Pete :

Sometimes it takes 4 or 5 resets in quick succession to reset it fully.

Pete :

Can you try that and let me know if there is any improvement?

Pete :

A lot of the audio processing is done within the microprocessor, so it is usually the most common cause of this phenomenon.

Pete :

- also check for dry or cracked solder joints around the microprocessor if you have the unit opened.

JACUSTOMER-de78jgkw- :

Ok I will try that.

Pete :

Let me know how you get on.

Pete :

I have to go into town shortly, but I will pick up your replies here by email and reply back again as soon as I can.

JACUSTOMER-de78jgkw- :

Also I don't have a remote and wondered if somehow a mute setting had happened which you can do on remote but no sign of a button on the machine. But I suppose resetting would obviate that

Pete :

Yes, a power cycle will reset the MUTING function.

Pete :

Ok, chat later...

JACUSTOMER-de78jgkw- :

I cant get to underside of pcbs without a lot of dismantling but looking through gaps at bottom it looks fine. No obvious signs of anything inside . The machine detects my input ok . i.e plug inti cd and it says 'in cd' and into phono it says 'in phono'. Rest m/p at least 5 times in quick succession.. One thing though - in the manual it says 'switch off' machne and unplug and then plug in holding A and B down. Nothing happens. Its only when I unplug, switch standby/on switch on and then plug in holding A and B - then it all lights up and flashes as its meant to.

JACUSTOMER-de78jgkw- :

had an email to rate your service but we are not finished yet? Barely started.

Pete : You can ignore the automated emails until you are ready to rate.
Pete : The standby switch should be on when you hold in A and B and plug the unit in.
JACUSTOMER-de78jgkw- :

so what now? I really don't want to spend 2 hours dismantling it to look at pcb. If you want to end it I would like at least a good steer as to the problem or wher to look. As far as i can see on the stand up boards they look clean. all internal connectors are plugged in. Am I looking at replacing output transistors? How can I understand how it worked 2 months ago and not now?

Pete : Can you confirm you have reset the microprocessor 5 times in quick succession?
Pete : if so, then the next most likely cause of failure is the electrolytic capacitors - these have a limited lifetime and can fail suddenly, exhibiting the symptoms you are experiencing.
Pete : Look for any swollen or bulging capacitors and replace them.
JACUSTOMER-de78jgkw- :

Please see above which answers your questions. specifically all the electrolytics are visually fine.

Pete : Ok, even though they are visually fine, it may be worth removing a few and testing them just to be sure.
Pete : Otherwise, the rest of the circuitry will need to be tested, and verified using schematics or test results from an identical unit.
JACUSTOMER-de78jgkw- :

It sounds like end of line then. I don't want to appear mean and grudging but not really convinced this is worth £26 of my money. I didn't expect you to repair it over the internet but having some knowledge of electronics and having built a few things in my time I don't think you have told me very much beyond what I have told you. I don't think electolytics just stop working from one time working to next time dead. I don't want to rate poor but Ok means I pay full amount? Am I being unfair?

Pete : I'm sorry I couldn't be of more help, but this really requires a full strip down and thorough circuit testing.
Pete : I am only paid a portion of your deposit for my time when you rate.
Pete : A poor service rating means that I am penalised.
Pete : an OK or higher rating would be greatly appreciated since I have spent two hours of my Saturday morning responding to you so far.
Pete : you can always ask further followup questions for free if you need to.
JACUSTOMER-de78jgkw- :

oh ok. I'll rate ok and pay. If I find time later to strip it down and take some pics to send , will you look at them.? It would be useful to have a direct email address as you already have for me (?) but if not it's *****@******.***

Pete : yes, you can reply back on this same thread at any time when you need further assistance
JACUSTOMER-de78jgkw- :

ok

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