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Sony STR DE505 Receiver, left channel out

jessek

Sep 23, 2011
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Sep 23, 2011
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This is an old receiver... probably originally purchased in 1998. Has worked wonderfully its entire life.

I just moved (short move... 25 miles). I moved it reasonably carefully... with my PC and not much else... on the floor of the car and then into a garage. The unit was stored in a clean/dry garage for a month or two. Now I'm connecting it back up again and the left channel is not pushing sound. I have lived in a dry climate for the last six years...

Troubleshooting:
  • I'm using the tuner to eliminate the possibility of bad cabling or components.
  • I'm listening through headphones... same symptom as with speakers.
  • The balance control seems to work, as I can fade down to nearly no sound if I turn the balance nob completely to the left
  • Volume nob is working and does not affect the left channel... no crackling.

I popped the top and am not seeing anything obvious... although I don't even know what to really look for... I'm not seeing any broken soldering or anything like that. It is quite dirty in there as I've never opened it up.

Any ideas would be much appreciated!!!
 

jessek

Sep 23, 2011
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Sep 23, 2011
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I'm going to bump this up one time....

Someone has to have something for me to try.. right? Or is it just time to find a new receiver?

This one does what I need it to for now, and it sure would be nice to bring it back to life.
 

davenn

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Sep 5, 2009
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hi Jessek,

ok before we start, what's your electronics experience? do you have a decent multimeter ? an oscilloscope ? soldering iron ?

looking through the circuit diag that olive2222 supplied a link to I can see a couple of good places to start to narrow down the problem :)

cheers
Dave
 

davenn

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Basically, for a start

there are 2 preamplifier IC's each IC has 2 outputs so thats a total of 4 outputs feeding 4 power amplifiers. Left front, Right Front, Centre and Rear

We need to determine that all 4 outputs from the power amps are working or not. then back track to find where a non-working channel starts working.

This is where an oscilloscope is ideal for signal tracing. Failing access to a scope, you may get away with using your headphones or a small speaker and do some audio tracing. ENSURE THE MASTER VOL LEVEL IS SET LOW!!!! if using small speaker or headphones

Dave
 

jessek

Sep 23, 2011
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Wow... thanks guys!!!

Electronics experience is minimal... but I am an IT tech :eek: and am not at all scared to dig around and see if I can figure this out. The way I see it, I've got nothing to lose... and knowledge to gain!

I work at a hospital, and we have an electrician here who I'm friendly with... I could probably borrow tools from him... have him help me out a bit if I'm not understanding something.

I'm going to dig into that diagram (thanks olive222!), see if I can locate the stuff that davenn is mentioning and I'll report back.

This is exactly what I was hoping for when I posted here!!!
 

jessek

Sep 23, 2011
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Also.... this thing is dusty inside. It's 13 years old, and I've never cleaned the inside of it...

What to use? Should I carefully vacuum it out with a soft brush attachment, or use canned air to blow the dust out? Am I at risk of causing more damage? I mean... what if the dust is what's holding this thing together. :)
 

OLIVE2222

Oct 2, 2011
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Your suggestions to clean the receiver are OK with a preference for canned air method. You can also use a soft paintbrush. Don't see any risk when done carefully. As you have 4 identical channels you can detect a fault by measuring any (significant) difference between the dead one and a working one.
good luck!
 
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jessek

Sep 23, 2011
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OK.. let me make sure I've got all of this straight before I dig in.

I'm going to clean out the inside of this thing.
I'm going to try to locate the 4 outputs from the 2 preamplifier ICs based on the board diagrams from the service manual.

Once I know what I'm testing, I'm going to plug the receiver in, turn on the radio and hold the headphone jack to what? Am I going to touch the metal headphone jack to something specific and listen for sound? What is that contact point?
 

davenn

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Sep 5, 2009
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OK.. let me make sure I've got all of this straight before I dig in.

I'm going to clean out the inside of this thing.
I'm going to try to locate the 4 outputs from the 2 preamplifier ICs based on the board diagrams from the service manual.

Once I know what I'm testing, I'm going to plug the receiver in, turn on the radio and hold the headphone jack to what? Am I going to touch the metal headphone jack to something specific and listen for sound? What is that contact point?

you need to make up a small patch cable for the headphone jack....

so you want the appropriate socket for the h/p jack to plug into. you only need 1 channel working. you want 2 wires coming off the socket. one from one of the channels and one from the common ground line. The other ends of the 2 wires... on one you will have a crocodile clip to be able to clip onto the 0V / Ground rail of the tuner/amp the other end going to a reasonably sharp metal probe, like a test probe off a multimeter. In that line you also want a small capacitor, say a 10uF 25V, just to stop from killing the headphone speaker of you inadvertantly put the probe onto a DC power rail.
With its sharp pointed end you can exactly on the IC pin, component leg or solder pad and listen for audio. REMEMBER WHAT I SAID in my previous post!!!
if you are going to use the headphone approach to detect the presence or lack of an audio signal KEEP the VOL down low so as not to deafen you. Alsoe aware that there could still be a significant loud click when touching a DC power rail. I wouldnt put the headphone right over the ear unless you really expect to hear audio at that testpoint!! :)

This is why using an oscilloscope is much better for this sort of thing :)

PLEASE heed warning ... I dont want to be blamed for your deafness
cheers
Dave
 

ozone

Jul 25, 2013
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Hi Jessek, Davenn and Olive2222.

I'm currently having the exact same issue with the exact same amp as described in Jessek's original post.
(STR- DE505, left channel out, all trouble shooting points are the same except...
when I balance completely to the left and pump the volume there is a faint signal coming through the left speakers, guessing this may be some kind of induction crossover effect?)

Anyway, I'm just wondering what became of Jessek's situation? Did you end up tracking down the fault and repairing it or did it end up costing more than it was worth?

I'm willing to attempt to track down my fault and solder in a new component, but i'd just like to know if you were successful, how much your replacement components cost and if you needed to take it to a professional in the end.

With the wisdom of hindsight, please let me know your advice!

Cheers.
 

davenn

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Sep 5, 2009
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Anyway, I'm just wondering what became of Jessek's situation? Did you end up tracking down the fault and repairing it or did it end up costing more than it was worth?

Dunno, the thread is almost 2 years old and he never came back to let us know the result :(

Dave
 
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