AV receiver - dodgy channel

[rubberduck]

Hi

I purchased a second hand Denon 2311 from AVforums as a stop-gap receiver to take me in to the HD sound age and get all my HDMI devices plugged in (I came from a Denon 3803). Its done the job ok so far but would like to get another year of use out of it before I upgrade. Am upgrading my projector this year.

Past few weeks it has developed a fault. The front left is significantly quieter than the other channels. I am sure it is the channels as have tried switching banana plugs round and the fault switches to whichever speaker I plug in to the front left channel. I can boost the channel to around +8db in the setup relative to the other speakers but I believe it sounds distorted slightly and is clearly not right. The fault also seems (to a degree) influenced by the temperature of the amp, how long it has been switched on etc.

2 questions - What could be the problem? And is it solvable easily (I only paid £70 for the amp). Could it be dust related and compressed air + contact cleaner could help?

Any ideas I suspect @lucid would know what the likely fault could be and if a repair is possible? Thanks in advance.

 

[lucid]

Repair is usually possible with most things so long as the parts, tools and skills are to hand. Whether it's worth the cost is a different question.

From your description, I think this is the early stage of the left front channel capacitor(s) going duff. Do you find it more noticeable when the amp is cold?

If you've not come across what capacitors do, they're a bit like a rechargeable battery hard wired in to the circuit. Their job is to hold a reserve of power, but only enough for a fraction of a second's use.

These caps are among the biggest in the amp, and that makes them fairly easy to spot.

If you have the skills, tools and time then it's not a difficult job to solder new caps in place. The biggest challenge will be getting to the board. As a DIY A job though you'll be looking at roughly £15 for parts. A third party repair agent will charge roughly £70 - £120 at a guess.

Contact cleaner and air duster won't fix this.

 

[rubberduck]

Contact cleaner and air duster won't fix this.

Thanks for the reply, yes it is worse when the amp is cold. I may try a repair if it gets worse and failing that will buy a replacement amp. Regarding the replacement capacitor.... I am only using the amp for 6.1. could I remove the capacitor from the unused channel?

 

[Mrp1980]

Technically you could although I would replace it, capacitors generally show signs of bulging etc when failing ,you may be able to trace back the channel just by sight and spot signs of the failure or you may not making repair much more difficult.
If you do attempt a repair be very careful as capacitors can hold a charge for a long time and can be very dangerous especially in the main power circuit.
I would begin by removing the top cover and giving it a visual inspection first then deciding if it is worth the time and effort to attempt a strip down to repair.

 

[lucid]

Thanks for the reply, yes it is worse when the amp is cold. I may try a repair if it gets worse and failing that will buy a replacement amp. Regarding the replacement capacitor.... I am only using the amp for 6.1. could I remove the capacitor from the unused channel?

Moving one of the other channel caps depends on them all being the same size and rating; sometimes the front channels have a bit more oomph to help with stereo performance. You might also find that the rear channel caps are in a different place, so you could end up dismantling more of the amp to do this. You could also find that the amp doesn't start if there's a cap missing from one of the channels, so you should avoid any short cuts.

Personally, I'd just go for the simpler solution of finding the correct voltage and microFarad rating and then get a new component. Take a note of these details from the side of the original cap. Buy the same brand name, stick to the voltage rating. You can increase the uF rating if a direct replacement isn't available.