very loud crackling/popping from only one speaker

[money4nothing]

hi guys, firstly, sorry if this is in the wrong section, but i couldnt see where else to put it.

my set up is: 2 Monitor Audio R252 speakers (one left, one right) running from a Pioneer SA-410 amp. they have been absolutely perfect for about 2 and a half years. until now.

anyway, today i woke up and went to turn my amp on, only to be greeted by incredibly loud crackling and popping from only the left speaker. it sounded like it could definitely be doing damage, so i turned it off immediately, then tried again, same problem. the crackling starts as soon as the red power light comes on, and even continues to fade out for a few seconds after the power is switched off.

so the first thing i did was try swapping the speaker wires in the back of the amp (so wiring right to left, and left to right), which caused the problem to switch to the right speaker. i also tried rewiring the whole set up completely with different speaker wire, which made no difference.

i came to the conclusion that the problem was with the amp, not the speakers, so i took the back off of the amp and gently cleaned as much dust away from inside as i could using a soft brush. i also checked all the fuses, which seem to be perfectly fine. im a complete novice when it comes to electrics so i didnt really know what to look for. after this i tested it again and it didnt make any difference, still the same problem through only one speaker.

i also tried changing the AUX cable to my computer, and even disconnecting it completely, which also made no difference.

so... is that the end of my amp? has it just died over night? i only bought it about 2 and a half years ago. i got it as a supposedly reconditioned unit, and bought the speakers around the same time after being recommended them by someone on this forum.

sorry this is a bit of an essay, but i wanted to be as clear as possible, and im not very clued up in terms of Hi-Fi. so if anyone can help me or offer any advice it would be greatly appreciated.

thanks a lot
Chris

[Barry]

Chris, the problem is definitely with the amplifier.

You will need to get it seen to by a qualified engineer. It sounds as though a capacitor may have failed on the noisy channel.

Sorry :(

[nekoni koban]

I had the same problem not too long ago, it turned out to be a cold solder joint in the output stage.. this means a joint was not heated properly when solder was applied, so the solder did not really fuse to the metal.. rather it just formed a mechanical contact, which over time lost electrical conductivity and became intermittent, hence the cracks and pops. This is almost impossible to find/fix yourself unless you have an oscilloscope and circuit diagram handy. With the amp on you can sometimes probe around the connections with a pointed wooden stick (it is good practice to keep one hand behind your back while you do this), and see if you can identify the bad connection this way. In my case I know the maker so sent it back to him. Sorry there is no easy fix.

[money4nothing]

thanks for the help guys, so do you think it is something that a qualified engineer could fix? and is it worth it? or would i be better off just binning it and buying something else?

[Firebottle]

Definitely something that can be fixed by an experienced engineer.
Could well be a dry joint as suggested by Nekoni, but I would guess it is a transistor breaking down. With a circuit diagram it should be a fairly simple task to identify the culprit, without one it might be a good approach to run the amp into a dummy load and see what the polarity of the loud output clicks are.

Cheers,
Alan

[337alant]

Just a tip for the future when you get noises like this or loud squealing noise or low frequency buzz or rasping sound, switch off and disconnect your speakers and get the output from the amp checked out before reconnecting your speakers.
If its a blown output transistor then you will definitely damage the speaker from that output, swapping over to the other channel will just damage the other speaker as well.
A simple test is to check across the speaker terminals with a voltmeter set on DC, if there ins more than 100ma then there is a fault on the amp and needs to be checked out as others have said above.
As Alan said it could be fixable so worth getting someone to look at it.

Alan

[Pete The Cat]

Much truth on AoS as usual. I had a problem with infrequent "popping" once. As others have suggested it's the amp, I ignored it until it thumped out my speaker, so it's worth getting seen to and should be simple enough to resolve.

Pete

[tubehunter]

hi Chris,

http://i514.photobucket.com/albums/t350/halx00/sa410/sa410_zps5e37aeb9.jpg (http://s514.photobucket.com/user/halx00/media/sa410/sa410_zps5e37aeb9.jpg.html)

Duncan

[money4nothing]

thanks a lot for the help and advice guys, i appreciate it. and thanks for the diagram tubehunter, although unfortunately i have no idea how to read wiring diagrams lol.

i dropped the amp off today at a local electronics specialist in coventry (FMTV Coventry). they say if its going to cost more than £50 to fix then they will let me know. i should find out tuesday so i will keep you guys posted on progress!

[Barry]

Let us know how you get on Chris.

[DSJR]

Coventry local to Essex? Cripes!!!!!

There used to be a couple of places in Ipswich that could service stereo gear and one 'did' one of my Crowns a few years ago. Surely there are ex electronic service engineers in Cambridge or thereabouts who could do the same, given a circuit diagram to work from?

[money4nothing]

Let us know how you get on Chris.

will do mate

[money4nothing]

Coventry local to Essex? Cripes!!!!!

There used to be a couple of places in Ipswich that could service stereo gear and one 'did' one of my Crowns a few years ago. Surely there are ex electronic service engineers in Cambridge or thereabouts who could do the same, given a circuit diagram to work from?

haha my home is in essex, but i currently study at coventry uni lol. the chap i gave it to seemed to know his stuff so hopefully all should be well :)

[money4nothing]

well im feeling quite confused now... i jut got a call from the guy who has my amp, and he said there is nothing wrong with it! apparently hes inspected all the components and connections and hes had it running all day without any issues :scratch:

im going to take my speakers and wires with me when i go to collect it on thursday to try and figure out what the problem might be

[StanleyB]

my set up is: 2 Monitor Audio R252 speakers (one left, one right) running from a Pioneer SA-410 amp. they have been absolutely perfect for about 2 and a half years. until now.

anyway, today i woke up and went to turn my amp on, only to be greeted by incredibly loud crackling and popping from only the left speaker. it sounded like it could definitely be doing damage, so i turned it off immediately, then tried again, same problem. the crackling starts as soon as the red power light comes on, and even continues to fade out for a few seconds after the power is switched off.


Aaah, the old dry joint problem on these Pioneers. If I remember correctly, Pioneer even added a removable plate under the amp so that engineers could access the bottom of the PCB. The legs of the output transistors and drivers need resoldering. It is a 15 minutes job from the moment you grab a screwdriver to unscrew the bottom. A common fault with most of the SA range or amps and receivers made in the late 70's and early eighties.

[money4nothing]

Aaah, the old dry joint problem on these Pioneers. If I remember correctly, Pioneer even added a removable plate under the amp so that engineers could access the bottom of the PCB. The legs of the output transistors and drivers need resoldering. It is a 15 minutes job from the moment you grab a screwdriver to unscrew the bottom. A common fault with most of the SA range or amps and receivers made in the late 70's and early eighties.

thanks for the help mate! like i mentioned above, the bloke who has the amp hasnt found the problem yet, but i will definitely mention this to him when i see him on thursday

[StanleyB]

The problem with these amps is hard to trace from scratch. It's one of those faults that you need to know about from past experience. The problem is with the kind of solder that was used in those days.

[money4nothing]

The problem with these amps is hard to trace from scratch. It's one of those faults that you need to know about from past experience. The problem is with the kind of solder that was used in those days.

ok fair enough man. thanks a lot. hopefully i can get this sorted

[istari_knight]

Thats a good call Stan, I had this problem on a SA-7800 couple of years back... Severe distortion on one channel but everything measured okay - A bit of head scratching later & the dry joint was discovered.

I wasn't aware its a common problem that affected the whole range... Learn something every day :) The same problem affects nearly all amplifiers that use Sanken SAP15 output transistors... I made some good beer tokens at one point buying all the "faulty" Arcam A65/A75 on eBay & reflowing the solder joints on the output transistor legs :D

[money4nothing]

just a small update for you guys. i took my speakers with me when i went to pick the amp up on thursday so i could test them in front of him, and surprise surprise... it all worked perfectly!

brought everything home and set it back up again and its been working fine ever since! so i have no idea whet the problem was and technically it never got fixed so im paranoid that it could happen again, but thanks again for the help and advise guys. i appreciate it