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RCA SP9972AW surround sound sub hums. One fuse was blown, replaced then both blown. Diode? Caps have not popped tops. Emitted typical smell of electrical burning but no signs of overheat or damage anywhere on circuit board. Schematic appreciated. Thanks, Mike

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  • theprivilege Apr 16, 2009

    Replaced both fuses, but the sub still hums

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6 Suggested Answers

robotek
  • 1512 Answers

SOURCE: Noise and popping on Sony STR-DA3ES

Sounds like its going to square wave clipping and poking a dc offset at your speakers. Happens when the amp reaches power supply ceilings. Pink noise such as "rain sound" will push the output stages and power supply to limits. If its on all channels, check power supply caps and check for dry solder joints. also look for that crappy brown hold down glue that goes conductive/corrosive. check all output stages particularly about discrete output devices that are attached to heat-sinks. They have a bad habit of dry jointing also. Good Luck

looked for a free manual on line for you
http://www.nodevice.com/manual/Sony/page139.html got heaps... but not your exact model. You may be able to cross reference one

Posted on Feb 03, 2008

SOURCE: Blown Pioneer Amp

Cambia los ICs amplificadores de audio

Posted on Apr 04, 2008

SOURCE: problem after replacing blown fuse

My dear friend your audio amplifier IC are damaged and you need to replace him.

Posted on Oct 01, 2008

  • 5 Answers

SOURCE: blinking standby mode light

With the unit unplugged, remove the top cover and use an ohmeter to check the 10 power transistors on the large heat sink; Q6050 thru 54 and Q6060 thru 64. If you find blown transistors (R<1 ohm from E to C) you'll need to replace them. Also check the large ceramic current sharing resistors, R6100 thru 04 next to the output transistors. These are dual 0.22 ohm, 2W resistors that typically fail open if overstressed. These are both common failures resulting from overloading the speaker outputs that will cause the proctection circuit to shut down the power supply at turn on. Good luck.

Posted on May 03, 2009

  • 4 Answers

SOURCE: center channel is not working

First make sure the centre speaker is not shorted, try a different speaker and new fuses. If this fails and you have electronics knowledge here is the link to the service manual...
http://www.enusbaum.com/blog/tag/service-manual/
The driver or power output device (FET or Transistor) is probably shorted if the speaker is not shorted.

Posted on Jun 10, 2009

  • 1 Answer

SOURCE: volume control blew out

i hade the same problem with the same unit and fixed it my self.
turns out the chip that is screwed to the heat sink was blown, and the resister that controles the fan burnt as well.all i did is ,get a datasheet of the unit and toke if apart went to the parts store and bought what was needed. the chip that is screwed to the heat sink has a part number on it whitch if you cant find the same can be switched with equivilant chip (find a datasheet of chip).
then my fan would not run ,i notesed that the risister was shot , the resister is color code witch means the resisters values. its a prety big job since the reciever has to be almost completely taken apart but very worth while .its ben workin like new for about 4 years since the repair with no problems or isues. hope this helps ad good luke.

Posted on Oct 28, 2010

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Why is there low humming in the receiver sub channel(only?)


Sounds like a shorted capacitor in the sub out circuit.

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Hi, I have a Harman Karddon sub - woofer. when I changed the fuse I get a humming sound. I would like to know if the type as in (2.5a 250v typeT) make a difference/


Fuses are either blown or not. The hum is from an ungrounded or unshielded cable somewhere.

What required the fuse to be changed in the first place?

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I have no output from subwoofer


Hello Fixya customer,

Thank you for your question.

Please check that the sub woofer and RCA cable are working by removing the RCA wire from the Sub woofer output of the Onkyou and touching the center terminal of the RCA plug. You should here a hum when it is touched.

If you get the hum, then the next step is to "Clear" the Onkyo by holding down the "VCR and Stby" button until you see "Clear" on the display. Warning, this will clear any settings special that you have made to the receiver, but will get you back to the Factory settings.

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In the setup menu are the speakers set to large or small? On some receivers if you have it set to large all the bass is directed to the right-left fronts.
On my pioneer receiver if the speakers are set to large the sub-pre-out only works if the receiver is in a surround mode, if its in stereo mode and the speakers are set to large the sub-pre-out is dead. If the speakers are set to small the sub-pre-out works all the time.
Also, some receivers won't send a signal to the sub-pre-out if there is no LFE discreet signal info from the dolby digital or dts bitstreem.
For example I have several older dvd's that light up the L C R SL SR icons on my receiver, but don't light up the LFE icon. I have other older dvd's that just light up the L and R icons meaning they are only recorded in stereo like a vhs tape recorded in dolby surround.
In my basement I also have a kenwood dolby digital receiver.
I've noticed that when a dvd only lights up the left and right icons the pioneer will automatically switch to dolby pro logic surround. The kenwood will only send the signal to the left and right fronts (stereo). If I manually switch it (kenwood) to dolby pro logic I'll get sound from all the speakers just like the pioneer, but it does'nt do it by itself.
Most receivers that have a tape monitor won't work in surround mode with the tape monitor on. The pioneer will let me use the tape monitor with dolby pro-logic but won't pass through a dolby digital signal with the monitor on.
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Apr 18, 2010 | Kenwood 107VR

1 Answer

Cant get bass, fuse is fine


You don't say if you've configured the Receiver to know you have a subwoofer (under Multicontrol - SUBW YES). Unless it knows about the Sub it won't send anything out that single "preout". You can get an RCA splitter to run that single output to both inputs in the Sub.

Just as an experiment, temporarily run one a pair of cables from the REC OUT to the Sub's inputs and tune an FM station to prove the Sub amplifier is alive. If it's still silent, it's dead. If there is sound (muffled) you need to go back to the Receiver to figure out why the Sub Preout is signal-starved.

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Connection a JBL surround cinema speakers with sub to a Yamaha


if you do not have the digital hook up from the tv to the reciever
304c659.gif then you will not get the subwoofer sounds or the dolby digital sounds
if you don't have this on your tv then just turn off the dolby digital when watching the tv , and you should be able to hear the subwoofer thru the virtual surround sound
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Did you try making sure the subwoofer is turned on under the set up menu on the Sony Receiver?

Press Set Up, Press the left or right button above the scroll wheel until you get to SW. It should say SW: ON or SW: OFF. If it says SW: OFF, use the Scroll wheel to scroll right until it says SW: ON. Also, make sure you aren't in 2CH mode, try A.F.D or surround sound.

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Even if it were a fuse, a blown fuse is merely a symptom not the solution. From the symptoms you've described the AMPs are the most likely problem. They are mounted to a large aluminum heat sink usually about center of the main board. There are several and they are a task to remove and replace because the entire board has to be removed... However, it's not too costly a repair and for a qualified shop something that can be done in a couple of hours - including testing. If you like the receiver get it fixed. Compared to most digital receivers today it's probably cheaper to fix this one than buy another. And a good repair shop will add years more life to that unit... Hope this helps. Bill

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