Question about Onkyo TX-DS939 Receiver
It started when the unit got hot (due to the two fans not coming on). This occurred about 6 months ago. Ever since then, the receiver (once turned on) would take between 2 to 20 minutes of being "on" before a click/noise occurred and sound would generate. Last week the receiver started making a high pitched feedback sound and we lost the all audio besides the feedback. I lost video and tracked it down to some bad connections on the bottom of the board (this is resolved).
I have a couple capacitors that look swollen on the main board, but unsure what else could be driving the sound issue. Any assistance or a schematic would be appreciated.
On my device there were quite a few bad solderings on power card. May be you have the same and it does not tolerate heat. Power card is that horizontal one on top, when you open the box. It is easy to remove so that you see under the card to check those solderings. One screw from left side of case, which holds that noise eliminator on AC lines, six screws from back keeping those connectors and four screws away from board corners. I disconnected only that connector in the middle of card, because it was a bit tight. Then I was able to turn that card upside down and after some fixes to those bad solderings device is like new again.
Posted on Jun 26, 2008
SOURCE: Onkyo TX-DS939
I have to ask the obvoius, did you get the manual, have you used the onscreen menu to set up the speakers, you can calibrate the speaker levels on the TV screen if you use the S video or RCA vidoe connection .have you turned off tape monitor?
Posted on Jun 28, 2008
This sounds like the amp is seeing too small an impedence load. In other words, the amp is expecting to see an 8ohm load and is being presented a 4 or 2 ohm load. This will force the amp to work really hard and generate excessive heat. Does the amp generate sound at all? ever? If not, then you probable have a situation with high frequency oscuillations that you can not hear. This means that the amp is sending out a lot of power to the speakers that the crossovers are shunting to ground. Without seeing the output of the amp with a scope, I can not confirm this. This is not a problem that will be solved remotely. Bring the unit to a shop and request that the output be examined using a scope to check the waveforms. I suspect that a bad feedback look internally is causing the generation of the high frequency signals.
Keep us posted.
Posted on Oct 29, 2008
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