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Receiver input or speaker problem

Last response: in Home Audio
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July 1, 2011 3:03:40 AM

Hello, I have an older Technics sax-530 receiver. It has worked well for years. I thought my large real old 15" front speakers were blown, so bought new ones because they kept going out, first left then right, intermittently. After I got new speakers it kept happening so I replaced all my speaker wire, to front center L/R and surround. Now they crackle occasionally. Still a problem. How can I identify weather this is a speaker or receiver input?

I have a newborn so trying to keep my costs down....

Thanks
July 2, 2011 3:29:53 AM

you put the speakers on the same crossover in the old box?
does the crackling happen at loud volume only?
maybe you can hookup a speaker to the receiver without a crossover and check functionality.
you might be able to do it with the 15 inch woofer.. but turn the midrange and treble down on the receiver first?
or
maybe you can get a speaker from somewhere for free or dirt cheap.
July 11, 2011 3:12:22 AM

Yes, it is the same crossover. The problem happens at all volumes. Sometimes as soon as u switch it on. I think there is a hole in the L/R speaker inputs allowing the wires to touch. I wanted to replace where the speaker wire clamps in, but it appears I would have to separate multiple circuit board connections to do this. That is why I wondered if there was a true way to test what the problem is before I start breaking solders.

Thanks so much

PS its been awhile, the crossover is also the input right? Like the red black snap covers? Forgive my ignorance.
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July 11, 2011 9:06:13 AM

i would assume the crackling to be caused by one of these three things:
1. a broken soldered joint (usually from pressing or pulling too hard)
2. a crackling transistor or digital to analog convertor
3. a problem in the circuit that is of either too much or too little power.


a crossover is an input.. i dont know if it is 'the' input you are referring to.
but
the signal goes into the crossover and the pieces of the crossover 'persuade' the different portions of the signal to go where they do.
the signal runs right through those pieces on the crossover, so if any of those pieces are bad.. you might hear a crackle.
not likely though.. since capacitors age and they get dull and/or completely stop doing anything at all.

seems like the highest probability of something crackling in a crossover would be the copper windings on the chokes.
sometimes those things have a coating on the copper.. and if they get too hot from too many watts, the coating melts or burns away.
that allows the copper to come into contact with itself and could be the sparks you are hearing.


to say what you did, about the one side doing it.. and then the other side doing it.
that says to me..
either there is something wrong inside the amplifier (like the transistors or the digital to analog convertor)
or
somebody had a party at your house and used those speakers with more power than they were supposed to be receiving.
maybe the speakers could handle it, but the crossovers couldnt.

all of the speaker input types make it easy to see if there is a connection between them.
the copper speaker wire is on the outside and in clear view.
if there isnt any extra copper dangling around.. it would be clear there isnt a short.

and also..
most receivers have a protection circuit.. if the speaker wires where touching, there would be a fail-safe mode that turns on.
i know the fail-safe protection started becoming generally available in the 1990's.
i can only assume your receiver has such a protection.

and if it does..
the chokes in the crossover wouldnt cause it to trip.
and the digital to analog convertor wouldnt cause it to trip.
the transistors would be my first choice, but maybe the protection circuit is seeing those crackles as part of the music.
usually transistors crack or explode.
but
it wouldnt suprise me if the transistors aged very well and the molecular structure started to degrade, and the sparks are caused by the gap in the molecular structure as electricity jumps the gap.


to be looking for a broken solder joint..
you should really know if anything was mistreated.
a cord yanked on.. or a speaker that was moved out of the way and the speaker cord got tugged on.
it can happen with greater ease if the solder is old and junk.. as if all of the 'glue' has evaporated.
i have seen older electronics with old and weak soldered joints before.
i was a child back then, and when you look at it.. it looks welded.. but sometimes it can break easy.
and
sometimes it simply breaks free from the circuit board, and the whole glob on top looks intact.

without knowing the age of the receiver, but guessing it is old, you really need to determine if the speakers are the problem to focus your attention on the receiver.
and
you really need to know if any of the speaker wires were tugged on, or if there was a chance of the speaker terminal being slammed into something from receiver movement.
because.. if none of these are practical, then it is probably simply time for a new receiver... unless you can find the problem and replace the piece(s) yourself.
a lot of the technics receivers from the 1990's ... if they are still working today ... out-lived in an era where electronics of that type would break about as often as the lcd televisions of yesterday.
sometimes it was the display that went out and the amp still worked.
sometimes it was the amp that went out and the display still worked.
other times.. the whole thing went dead and nothing turned on.

this website should be of some help:
http://www.bcae1.com/

especially these three pages:
http://www.bcae1.com/trnsistr.htm
http://www.bcae1.com/tranfet.htm
http://www.bcae1.com/ampfail.htm
July 12, 2011 12:49:09 PM

Hey thanks alot. I have a feeling that it was tugged on at some point. between children bumping the speakers and my two rowdy boxers. I know it is not the speakers as they are brand new. I think I will check the solders.

Thanks for the info, it is a great help
July 12, 2011 4:09:37 PM

i hope SOMETHING works out for you.
as i have looked at things myself and couldnt make any determination without using some diagnostic tools that i dont have or really know how to use.

i broke the solder on my receiver because i kept screwing the bindings too tight.
a broken solder joint is pretty rare, since the 'abuse' of being tugged on has to come from somewhere.

any other time, if the solder is loose.. it probably got hot from something old and not working right.
and to add more solder means it is only going to break again with more heat (unless you use different solder that requires a hotter solder gun to melt it).


there was a video running around here on the forum about capacitors buldging or leaking when they go bad.
i felt heart-warmed that the person found some leaking or buldging caps, because all of the times i have looked at circuits without any clue as to what was broken.. there was never any burnt pieces or buldging/leaking capacitors.
to say that it all looks brand new, but it isnt working.

i hope to take some classes to learn how to diagnose my own electrical problems.
because when things break, and it only costs like $50 or less to repair it.. you would probably be adding another $100 - $200 for labor when somebody else does it for you.


like right now..
i have a broken x-fi elite pro soundcard.
i looked it over and i dont see anything wrong with any of the capacitors.
but
every time the bass hits, there is a crackling distortion.
makes me think something isnt getting enough electricity for when the bass hits.
although, i switched to the digital output and the bass was creating distortion then too.
so i either have to dive into thought about how the bass could be distorted in digital form.. or assume the board has a virus (pretty crazy!).
i can only imagine there is a lack of electricity going to something, and the bass (even in digital form) requires more electricity.
i find that a bit hard to believe though.. since processors use a steady stream of electricity, and that bit of electricity only gets sucked on when the processor is used more.
but
maybe the problem is close to the digital section of the board, and that is why the bass distorts in digital form too.
because the processor is right next to the problem piece on the board.. and anytime the processor gets a chance to 'provoke' the problem.. it does and the whole thing distorts.


but like i said.
isnt it a bit bogus to come all this way with trying to make the problem logical.. only to not know how to fix it?

i cant even find out how to easily test a capacitor.
so if i wanted to try to change the capacitor.. i would have to do all of them.
there is 47 capacitors on the board !

i would have some fun with an electronics repair person via email.
maybe i will try to hunt down a forum and ask for advice/opinions.

anyways..
best wishes.
July 24, 2011 6:17:58 AM

Sorry its been a busy time as I work in the restaurant industry on the coast of Maryland. If you think its hard to pull out a soldered joint, and its hard to test capacitors what do you think? The issue has become really random. I did discover that one satellite speaker was shorted, and so disconnected it. But the problem still sometimes surfaces. Mostly when someone steps heavily around the equipment. But also when the bass hits hard.
July 24, 2011 8:24:30 AM

not hard to pull out a solder joint.
the most stubborn connections with a bunch of pins simply require you to use a solder vacuum to suck up the solder when it is hot.

otherwise you could melt one soldered pin and raise it up.
then melt the other pin and raise it up.
repeat as necessary until piece is out.

if there is a problem of output when people walk heavy or the bass hits.. it really sounds like the loose soldered connection is proving to be true.
i cant imagine anything else if simply walking heavy by the receiver is causing output to stop.
hardly anything electrical there, unless there was some magnetism of the person (or some other electricity) that was really interfering with the amplifier's pieces on the circuit board.

and if you dont walk hard there is output still ?
probably gonna have to open it up if you want the annoyance to go away.
maybe it will sound a bit better after you solder the connection back.
!