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Sony STR-D350Z no sound

 
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spat72



Joined: 12 Jun 2008
Posts: 5

PostPosted: Thu Jun 12, 2008 10:03 pm    Post subject: Sony STR-D350Z no sound Reply with quote

New here! I am not really good at repairs due to little knowledge. I am a former Automotive tech and did quit well with electronics in that area. However audio/video is out of my league. I have a STR-D350Z reciever that has no sound. If I select tuner and crank it up all the way I can hear a little of my input source regardless of the port it is connected to. If I select the source it is connected to there is no sound at all. Lost the remote so can't check for mute. However the manual claims mute will be displayed on panel if activated and is not displayed on panel. Not sure what happened but it was working one night when going to bed and not working when I got up. I leave system on most of the time. I used it for all audio. TV, Computer, Radio, CD, ETC.. I opened the unit looking for a fuse but found non. I don't see any obviouse burned components any where. I considerd cleaning the volume rehostate but not sure how that should be done on modern equipment. I find it odd that the tuner when selected plays sound of other input but not radio sound. My guess is something crossed up with input selections? I see some yellowing on the board under each chip but nothing drastic. I went to pawn shop for a replacement, that was a joke! I couldn't believe the prices they wanted for stuff. I noticed many items for near the same price as new but these items where 10-20 years old. Some even higher than new! Like a Sony reciever, I don't know the modle, probably 15+ years for $233 not even surround sound. A JVC standard reciever $358, about the same age. I might agree with high prices for something like an Onkyo or Yamaha. Oh well. if anyone can point me in the right direction I would appreciate it.

Thanks!
Spat
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vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Fri Jun 13, 2008 12:45 am    Post subject: Reply with quote

Sounds like a problem with one or more of the input select switching Ic's---I think it was the TCxxx series(some which are already no longer available). It was rather common with the older Sony models. Without diagram/test equipment or familiarity with ckt, it is not gonna be easy.

otherwise, you could try following the signal path & see where it enters any of the switching Ic's. sometimes the failed switchin Ic tend to latch up & run too warm. You could even try the finger rub trick(make sure vol is down) where you simply touch either side of the Ic pins & immediately notice a change in volume... etc
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spat72



Joined: 12 Jun 2008
Posts: 5

PostPosted: Fri Jun 13, 2008 4:17 am    Post subject: Reply with quote

vtech wrote:
Sounds like a problem with one or more of the input select switching Ic's---I think it was the TCxxx series(some which are already no longer available). It was rather common with the older Sony models. Without diagram/test equipment or familiarity with ckt, it is not gonna be easy.

otherwise, you could try following the signal path & see where it enters any of the switching Ic's. sometimes the failed switchin Ic tend to latch up & run too warm. You could even try the finger rub trick(make sure vol is down) where you simply touch either side of the Ic pins & immediately notice a change in volume... etc


OK I have located an IC labeled "function" and I can see it has a relation to all the input jacks and the tuner. I am assuming this is what you are reffering to as input select switching IC. It is a LC7822. I could not find anything labeled with a TC...

Sorry for my ignorance but trying to finally learn some of this stuff. I do have a service manual with schematic. I also have a basic meter. Sadly I lost my good Fluke meter to theft a few years ago. I now work as an electrician so I have one of those clamp ameters with the built in AC/DC volts and ohms. Not really much but plenty good for my daily needs.

The "function" IC does have some discoloration on the board but nothing visible on the IC itself. If this is giving the problem is there a way to jump anything to verify before replacement. Or is there a way to prob one of the terminals for a reference. Sorry I don't have a scope if that is the type of data I would be looking for. I know I could just go get a new unit for a reasonable price but I have been wanting to learn electronics a long time and now is a good time. As I am out of work on temporary disability and not much money. Oh I also noticed discoloration under the amp drivers as well but the amps themselves look clean. If I get this fixed I think I will install a fan or two. As mentioned before I leave my systems on most of the time so that would probably be a good preventative measure.

Thanks for your help!

Spat
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vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Fri Jun 13, 2008 3:24 pm    Post subject: Reply with quote

..sorry I see, it is the LCxx series made by Sanyo.

Forgot to mention that before anything, you should try unplugging &plaugging the unit just to make sure you don't have a reset problem (unlikely)
Are you able to read/follow schematics/signal?
The LC is a good place to start & may infact be where the trouble is? (not sure about the discoloration though as I don't remember ever seeing that--is it running warm/hot?)

It is used as a simple analog switch(half for L & half for R channel) and ofcourse the easisest would be with a scope otherwise you can use a small cap to momentarily jump the in/out pins along the signal path for verification.

Once you find the signal path for lets say the tuner(either L or R), select it & follow it thru the IC. with volume turned down, you can use the jumper cap(like a 10-100mf electrolytic) to bypass it for testing. It is a simple in/out select procedure thru the IC. I might add that it is usually a power surge/brownout of some sort that causes these switchers to fail.
While I commend your enthusiasm in troubleshooting & figuring stuff out, this may turn out to be more of an expense for someone in your situation. Lets say the IC was bad; do you have a soldering iron or a source for the part? (surely you are aware of that)
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spat72



Joined: 12 Jun 2008
Posts: 5

PostPosted: Fri Jun 13, 2008 4:47 pm    Post subject: Reply with quote

vtech wrote:
..sorry I see, it is the LCxx series made by Sanyo.

Forgot to mention that before anything, you should try unplugging &plaugging the unit just to make sure you don't have a reset problem (unlikely)
Are you able to read/follow schematics/signal?
The LC is a good place to start & may infact be where the trouble is? (not sure about the discoloration though as I don't remember ever seeing that--is it running warm/hot?)

It is used as a simple analog switch(half for L & half for R channel) and ofcourse the easisest would be with a scope otherwise you can use a small cap to momentarily jump the in/out pins along the signal path for verification.

Once you find the signal path for lets say the tuner(either L or R), select it & follow it thru the IC. with volume turned down, you can use the jumper cap(like a 10-100mf electrolytic) to bypass it for testing. It is a simple in/out select procedure thru the IC. I might add that it is usually a power surge/brownout of some sort that causes these switchers to fail.
While I commend your enthusiasm in troubleshooting & figuring stuff out, this may turn out to be more of an expense for someone in your situation. Lets say the IC was bad; do you have a soldering iron or a source for the part? (surely you are aware of that)


Yes I can read schematics fairly well as to symbol recognition and current paths. I remember the basic function of transistors, my experience is lacking the knowledge in relation to values and exactly how capacitors work. Need to study that! I have a few electronic supply websites bookmarked. But prefer to go to radio shack if possible. Though they don't carry much of that stuff anymore so I will probably have to resort to something else. I do pick up "Nuts & Volts" every once in a while so maybe something in there will help as a resource.

I specialized in electrical systems in automotive but that was much simpler than this stuff. That was mostly resistors, diodes, and switches. Didn't get much work internally on anything with logic due to manufacturer not releasing any info related to those components. They just offered a few tests to check by terminal probing. If anything was out of spec then you just replace the whole asymbly.

I do have a soldering gun 100w on/off that would be too hot for an IC I think? I also have an iron selectable 10/20w I think it was. I will try to work on it over the weekend. Not feeling up to it today. I have a couple of beggining electronics books so I may read some of that later today in relation to IC's and soldering.

Wish I did have a scope. Almost bought one after I took a class on using them for automotive but they where so expensive. Altogether I don't think the price was out of the norm just more than what I could afford. I think the cheapest one was about $1500 but had a very low sample rate. The better ones with high sample rates and lots of bells and whistles ranged around $3,000 - $5,000. The nice part was these where all hand held portable units. This was back around 2002. I haven't looked at any since then. Maybe less now?

I also have a Sony STR-AV900 that I am using now for my home office. Any info on reliability of them? So far so good! I think I will install a fan on it to improve my chances of a much longer life. But I sure miss having one for the entertainment center.

Well thanks for your help! I will post back in a few days on my results.

Spat
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PostPosted: Sun Nov 30, 2008 11:03 pm    Post subject: Reply with quote

Hi, How I can unlock Sony S.T.R-D350Z??? Question Question Question Question
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