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Problems w/Sony STR-DX835

Last response: in Home Audio
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November 21, 2010 11:29:43 PM

I am the original owner of a Sony STR-DX835. Recently I resoldered the audio amp modules when I experienced shutdowns and discovered many of the solder joints on the main amp and rear/center/subwoofer amp boards showed cracking and had become intermittent (never realized my rear channels had stopped working :(  I've read this is a common problem.

Now, it seems to have developed a more subtle problem. I have a subwoofer connected and during an HD input the LFE indicator (essentially a VU meter for the subwoofer) seems to jump from 1 bar to 3 bars (as opposed to a more "linear" transition. Also, when this happens, I can hear thumps and distortion coming from the sub (I have sinced reduced its volume to keep from blowing the speaker). Everything seems to be OK on standard (non-HD) input.

Any ideas what's going on, short of having to replace the whole receiver (I doubt the right parts are still available for this nearly 15 yr/old machine).

Thanks in advance....Steph
November 22, 2010 12:20:41 PM

well yes, you do probably have cracked solder connections. A good bench tech could fix the broken connections or traces, but it does take experience and soldering equipment. It really does not need parts, just some circuit board repair.
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a b Ù Sony
November 22, 2010 4:29:14 PM

I am not sure what you mean by HD input since your receiver does not have HDMI? If your receiver only has analog L/R audio inputs you may be overloading the input and that would cause problems. Some older ProLogic receivers had an input level control to avoid this. If you can turn down the output at the source that would also work. The non HD source may have less dynamic range and so would not overload the input. This would not apply to a digital audio input.
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November 22, 2010 7:45:28 PM

americanaudio/soundguruman,

Thanks for your inputs.

Apologies for misspeaking about the "HD Input" :(  What I meant was that I had gone to HD video and surround sound. You're right. This unit does not support HDMI, only the 5.1 ch. audio.

To be more clear about my problem....the 5.1 audio (using optical...pro logic, etc.) was working fine, including the subwoofer output (and LFE indicator), both before I discovered the bad solder connections problem (albeit the rear amp output was greatly reduced because of the bad connections) and after I fixed it . It's been recent, after enjoying about a year of great surround sound, that my current problem with the subwoofer occurred. So, if there is an overload issue, it's happened recently (BTW - not obvious there's any kind of adjustment for that).

I do have the service manual and checked the schematics. Lots of complex h/w (audio DSP, A-D/D-A converter, a few op amps, etc.). Not sure of where the subwoofer info is "decoded" (my guess is the audio DSP). Somehow, it seems the sub is processed differently when in 5.1 vs "normal" (maybe that's a "Duh!" statement since the sub is fine in stereo mode, but acts up in 5.1 ;) 

I only have 1 5.1 input active (DishNetwork DVR) and it's possible that could have become the source of the problem. It might also be one of the audio opamps or associated components or related solder connection issue (I should be so lucky) causing it. I could also shift the DVR to another input to see if it's input channel related (tho, I'm guessing not).

Thought maybe since so many people were familiar with the Sony solder problem, someone might recognize this one, as well.

Thanks again. I'll repost if, and when, I figure this out. Meanwhile, time to pull otu the scope and DMM and/or find another known working 5.1 input.

Cheers...Steph
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