Reciever not playing at all

[rotco]

Hi all
I've got an old home theater receiver which is not making any sound (even in headphones).
i opened it and saw few faulty capacitors (small ones and both big filter capacitors)
i would like to start a hobby in electronics and fixing stereo stuff.
i wanted to ask if, as first step, there is a direct relation between the big two filter capacitors and fact that there is no sound?

Thanks

I'm assuming that also the other small capacitors are also causing other functions not to work properly.. but as first biggest step, i think the bigger ones are more affecting the issue. is it correct?

 

[mbz]

A model number would help, but generally the home theatre amps have microprocessors inside for general management. Also they have
heaps of functions/multichannel/video/digital... which makes them very complex to repair, so as a first step it's a tough place to start. However
if you consider the receiver as disposable then why not...

A better place to start would be a basic integrated amp rather than a receiver. Something like the NAD3140, 3020 or the PE series are both
plentiful and generally easy to work on, despite the birds nest...

Back to your receiver, cause could be just about anything, like,
- amp is in protection. A component has failed eg, short circuit, putting abnormal high dc voltage on the speaker line, The protection relay disconnects the
speakers so as to protect them
- power supply failure, blown transistor, voltage regulator or maybe just a fuse
- and heaps more

Suggest you try and locate the service manual, start at hifiengine, need to register, it's safe, no spam.
Also need basic tools like a multimeter, soldering iron, solder pump etc,,,

Important: You will need to take voltage measurements on a live/powered up unit and be comfortable with this, mains voltage can be lethal...
On the positive side you will learn heaps, there are plenty of quality vintage units that can be had cheaply...

 

[rotco]

thanks for your quick and detailed respond
the model is Sansui rz-5700av.

I'm doing "training" on it since i got it for free, and i think its not worth a lot of money.
of course i already have a basic troubleshooting and experience in vintage stereo receivers (which is much more friendly and simple since they having "traditional" electronics components, rather than complex "micro chip" PCB).

Im trying to understand basic facts now:
1. "leaked" and swollen capacitors are 100% Not functioning?
From first "visual inspection"
do they have direct relation to "no sound" problem?

2. I think that more related cause to "no sound" issue is the transistors. since its have few channels (i think 5), i tried them all, and none worked for me.
so i guess its not related to them. also, they are more "durable" than capacitors.

The power supply is good and also the relay - its not related to electrical power. or dusty potentiometers.
Of course I denied the possibilities of "software settings\digital features" that may not making any sound such as mute, source, A/B channel etc..

thanks

 

[whoaru99]

Are you positive the caps are actually bulged and leaking?

It is not uncommon for some glue to be mistaken as leakage, and some caps having plastic covers can look bulged but the caps themselves are not bulged.

 

[rotco]

Are you positive the caps are actually bulged and leaking?

It is not uncommon for some glue to be mistaken as leakage, and some caps having plastic covers can look bulged but the caps themselves are not bulged.

Believe me, i never seen such a low quality capacitors before.
almost half of them was swollen and the electrolytic substance was "melt" beneath them.
I guess its "only' ~15 years old receiver.
and usually I'm a vintage guy who love to deal with the 70' receivers (Marantz, Sansui), and their cap's are at least 40 yo, and wasn't in such a poor condition.

 

[whoaru99]

Frankly, sounds like glue to me.

Pictures?

 

[tyeeslayer]

Start here.
http://audiokarma.org/forums/index....udio-gear-eh-heres-the-tools-you-need.333423/

 

[Blue Shadow]

Are you positive the caps are actually bulged and leaking?

It is Most Common for some glue to be mistaken as leakage, and some caps having plastic covers can look bulged but the caps themselves are not bulged.

FIFY. When was the last time we actually saw a claim of leakage that was not glue? Maybe one of the big caps in a Pio unit with a bit of crud around the terminal. Other than that they all seem to be glue.

 

[mbz]

I have to agree with others that the "leakage" is actually glue, especially if it's on the sides of the caps.
The report that most caps are swollen is a concern.
Post some photos of the worst affected caps.

Specifically to your questions,
1. Multiple failed caps may result in no sound, ie, signal path caps
2. Since all 5 channels are affected you either have the same fault in each channel, ie, 5 faults or 1 fault in a central location
like the power supply or the amp is in protection. Again the caps may be the root cause, photos needed...

I will try and get some test points for the power supply.

 

[mbz]

The Rx has a STK4231 chip in power amp

Measure dc voltage at points indicated below.

 

[redk9258]

https://www.hifiengine.com/manual_library/sansui/rz-5700av.shtml

 

[OMGCat!]

I'd have to agree on the glue especially if it's the old corrosive kind. The small caps will typically split the tops when they leak though I've seen a few with the rubber seals on the bottom being pushed out (this was never on a piece of audio gear however, only in Capacitor Plague motherboards).
Start with the basics as mbz has shown. Do some voltage checks and see where it leads you.

 

[rotco]

Hi all
thanks for help
i guess that if most of yo say so...you're probably know what you're talking about (and i learned something).
i looked for it in google...and see that its not common to see pictures like my case, and usually faulty capacitor is just swollen\exploded\vent on top.
which is not my case.
but, what make me suspect, is, what's the reason (from the start) that should be glue over there.
so, maybe is just to assure mechanical reinforcement. but i would expect to see it only beneath, and, "hand made" with careful and in specific week areas.
but my case is just seems like an amorphous random puddle surroundings.
I'll let the photos speaks for them self. (I started to peel off few spots)
its dusty and few areas looks pretty bad (like burned component) it may seems worthless, but i just want to try on it. hope you could see and understand thru the pictures.
(BTW, sorry for my lame English)

Thanks a lot.

 

[dr*audio]

It's glue. The manufacturers glue the caps down, because, believe it or not, during shipping the caps can vibrate back and forth enough that the leads break!

 

[rotco]

It's glue. The manufacturers glue the caps down, because, believe it or not, during shipping the caps can vibrate back and forth enough that the leads break!

Makes a lot of sense to me.
BUT!
Its looks so "unprofessional" way to use a glue.

 

[whoaru99]

Makes a lot of sense to me.
BUT!
Its looks so "unprofessional" way to use a glue.

That's the way it is in some cases. And, the problem with the unit may be the glue, not the capacitors at all (although to thoroughly clean up the glue you'll usually need to remove them and other bits, then might as well replace).

In some conditions the glue can become corrosive and cause damage to components and or shorts. You see this in your unit.

Search the term "DSBG" here on AK and you'll see plenty other examples.

 

[dr*audio]

Any place you see the component leads have turned green where there is glue on them, the glue needs to be scraped off, and the green corrosion needs to be scraped off or the component replaced. Interestingly, the glue does not always cause this corrosion. I think it's a reaction to something in the environment where the equipment was used / kept, like salt air or humidity.

 

[NAD80]

Here is the damage the glue can do.http://siber-sonic.com/audio/carnage.html

 

[rotco]

Thanks angain everyone.
I read some information in the net, and saw that it only related to products manufactured between 79 to the mid of the 80'.
So the reciever im talk to, not included. (i guess its belongs to the early 2000).
So, i will start with the voltage meaaurments as @mbz suggest.
Thanks, and i will come back with updates..

 

[whoaru99]

Thanks angain everyone.
I read some information in the net, and saw that it only related to products manufactured between 79 to the mid of the 80'.
So the reciever im talk to, not included. (i guess its belongs to the early 2000).
So, i will start with the voltage meaaurments as @mbz suggest.
Thanks, and i will come back with updates..

I don't care what it says for dates, the corrosive glue problem clearly exists in your unit and is the very first thing that needs to be addressed. Specific physical evidence always trumps generalities.

It is a complete waste of your time to do anything else first.