[rollingradios]


I've been reading here for some time.

Not an idiot here, but not a fanatic either.

I have an older onkyo 7.1, was a box deal with 6 spkrs and sub. Ran it for 2 yrs, put it in storage. Recently broke out the rcvr, hooked it to a sound bar and hooked up sub. Ran fine. Got the surround spkrs out and hooked up. Within a week the rear channel went out. I was able to piggyback the r spkrs with the center surr spkrs, worked fine. 

So, thought, well it's an older rcvr, I'll get a used nicer one. Got a used Denon 791. Hooked all up, great. 7 chs working. Awesome. About a week, the rear channel blows out just like the onkyo. Piggyback the rear spkrs with the center surr spkrs, works fine, just like the onkyo.

 

Question:

Makes absolutely no sense to me why two rcvrs blew rear channel.

Common sense says, some weird impedance issue loading rear channel at too low load? But then why can those spkrs sister with the center channel and run fine.

Fluke? Just dumb luck that two receivers blew same rear channel?

What am I missing? Thanks

 

[noah katz]

Did you check the rear speakers for frayed wires?


In case it's internal to the speaker(s) or the wire, check them separately with an ohmmeter while respectively whacking the box with your hand and while wiggling the wires.

 

[arnyk]



Quote:
Originally Posted by noah katz  /t/1517602/7-1-rear-channel-blew-on-2-different-receivers-help#post_24353596


Did you check the rear speakers for frayed wires?


In case it's internal to the speaker(s) or the wire, check them separately with an ohmmeter while respectively whacking the box with your hand and while wiggling the wires.

It could also be rubbing voice coil. If the ohmmeter check shows a DC resistance near the rated impedance of the speakers, then all should be well.


If anybody needs a good audio grade digital multimeter:

http://www.amazon.com/UNI-T-Digital-Ranging-Multimeters-Multitester/dp/B007THZMWI

 

[rollingradios]

The wires are new, and don't forget I'm currently using these same speakers piggybacked on the center channel, it's working.

 

[mike911]

Could the speakers be driving the receiver too hard? I know most htib speakers are 4ohm, so maybe that could be your problem. Is the receiver running hot?

 

[arnyk]



Quote:
Originally Posted by rollingradios  /t/1517602/7-1-rear-channel-blew-on-2-different-receivers-help#post_24353757


The wires are new, and don't forget I'm currently using these same speakers piggybacked on the center channel, it's working.

This isn't about wire quality its about workmanship. Not that making an error like this is uncommon or makes you seem stupid. Been there, done that!


What's stupid is not double checking and even redoing the work, and then treating a simple shorting strand of wire like its a federal case. ;-)

 

[rollingradios]

Ok, you're right, don't assume.

I ohmed out rear speakers. Check. I then hooked speaker wire back up and ohmed at where they terminate to receiver. R rear speaker showed flake reading. Pulled that stretch of wire out and replaced it. Rear channel now works, not blown after all.

That is good news. I suppose these receivers have some protect shut down on each channel? If so, my old onkyo probably still works on rear channel too.

Thoughts?

Summary, a smart guy would test speakers AND wires, even if they are new. I'm not always smart. Don't tell my wife that though.

 

[rollingradios]

Speakers checked at 8 ohms, receiver was never hot.

 

[rollingradios]

Ok, rear channel went out again

 

[Foxbat121]

How many receivers you have to go through before you realize that your surround speakers or wires are to blame?

 

[ss9001]



Quote:
Originally Posted by Foxbat121  /t/1517602/7-1-rear-channel-blew-on-2-different-receivers-help/0_100#post_24356463


How many receivers you have to go through before you realize that your surround speakers or wires are to blame?

+1

 

[rollingradios]


I really don't know Foxbat. Maybe several million. 

I was hoping someone may have experienced something similar. The fact that I was able to combine the rears with the centers and IT WORKED is what's puzzling. I tested speakers and wires with ohm meter, everything checks. At some point I will pick up another pair of speakers to try on the rear, but until then I thought someone might chime in with experience or ideas rather than condescension

 

[ss9001]



Quote:
Originally Posted by rollingradios  /t/1517602/7-1-rear-channel-blew-on-2-different-receivers-help/0_100#post_24356734


I really don't know Foxbat. Maybe several million. 

I was hoping someone may have experienced something similar. The fact that I was able to combine the rears with the centers and IT WORKED is what's puzzling. I tested speakers and wires with ohm meter, everything checks. At some point I will pick up another pair of speakers to try on the rear, but until then I thought someone might chime in with experience or ideas rather than condescension

why don't you swap the fronts, plug them into the rear terminals? that would narrow it down to receiver or at least eliminate the speakers.


you probably know this since you're measuring with a meter - the combining of rears & center changes the impedance load on the receiver, depending on whether you wired them in parallel or series. if you connected them so they'd be series, you are putting an easier load on the receiver (2 pair of 4 ohms >> 8 ohms) but if they are parallel, they'd be putting a worse load on the receiver (2 pair of 4 ohms >> 2 ohms)


just because it works combined is no guarantee, because if the issue is ultra-low impedance dips at some freq's, combining in series would cover that problem up.


you need to eliminate or confirm the speakers or wiring by plugging in a different set of speakers into rear terminals. and you already can do that with the fronts, a simple cable swap.

 

[rollingradios]


You're right, and I do need to try flipping the centers and rears to see if then the center will cut out. 

Do you know if these avr type receivers have protect mode on each channel? I'm guessing so since I found my rear channel came back for a brief time.

When I piggy'd the rear and center, it was parallel and 4 ohm load. They continue to play even with the low impedance. Puzzling to me what is going on in these particular pair to cause a channel to drop out. I'll do the switch center to rear and see what happens.

 

[ss9001]

protection mode would be for all.

 

[rollingradios]

Then how does the rear channel go out and come back?

 

[ss9001]

that sounds like an intermittent connection problem.


my experience with protection mode is that the receiver just shuts off, not a particular set of speakers. wait a minute and turn the receiver back on, and unless the amp board went into lockdown, it should power back up. that is the classic set of events. it the amp board locked down, it would not power up and you'd see one of the front panel LED's flash (I can't remember which one for your generation of models). but 2 channels and 2 channels only is not a classic symptom of protection mode shutdown.


if it's an intermittent sound>>no sound>>sound again, you could have something going on in your speaker setup...wiring, speakers themselves, cable connections, rear panel terminals. etc. or it could be a bad relay in the receiver although "blowing" 2 receivers with the same problem & same 2 speakers has very low probability

so physical connections or speakers is the place to start. it could be you have such tight spacing for the receiver(s) that the rear is pressing against a wall or cabinet, causing wiring shorts or it could be crimped wiring itself...who knows? we don't because we're not the ones sitting in front of it seeing the problem or troubleshooting.



see Foxbat's post.


you're asking good questions but no one in a forum can give you a certain answer as your problem because we're not there to see the symptoms as you know

all we can do is throw gum against the wall and hope it sticks

if it were me, I'd be looking into what we suggested about swapping speakers before jumping to any conclusions. if you can rule out the speakers and wiring, then you may be looking at other things, bad terminal connections, bad wiring connections, over-sensitive relays, etc.


banana plugs best & safest to use

spades work well too but harder to fit with these tightly packed terminals

bare wiring - not a good idea at all due to potential shorting - could be even a positional thing or when wiring is pressed against...we don't know because we can't see it.


but if this were me, I personally would try obvious rather than looking for the exotic as reasons - swapping speakers and cables to see if I could rule out those first. then look at plugging the same 2 speakers into another pair of terminals to see how it works with your rears as fronts.


try to reproduce the problem by swapping the fronts & rears, both pairs. combining them with the center doesn't accomplish anything since you have them connected them all in a non-standard way....swapping a stereo pair of rears for a stereo pair of fronts does accomplish something. if it's the receiver, your fronts will either do the same thing in the rear and the rears as the fronts won't . if it's the rear speakers, they may "go out" in both positions. that is the place to start.


KISS diagnostics works.

 

[noah katz]



Quote:
Originally Posted by ss9001  /t/1517602/7-1-rear-channel-blew-on-2-different-receivers-help/0_50#post_24357393


that sounds like an intermittent connection problem.

I once had a store-bought speaker with a bad solder joint on the input terminal.


So you could have a flaky speaker that starts working when you move it.


Did you try the whack test?

 

[ss9001]



Quote:
Originally Posted by noah katz  /t/1517602/7-1-rear-channel-blew-on-2-different-receivers-help/0_100#post_24358062


Did you try the whack test?

have to LOL

because there's truth there

to add my story to yours, I own a Sansui '79 quad receiver that was top of the line in its day. after owning it for about 5 yrs or so, sometime by the mid-80's, it developed a few intermittent channel dropouts which gradually worsened to one day in the late 90's - no sound at all! I then learned about its design issues - double sided circuit boards that had pass-thru cold solder joints that over many heat-cool cycles starting to crack with tiny gaps opening up. Heated up, you may get sound, but cold you'd lose 1 or more channels. I've had it re-capped and fully restored.


sometimes I felt like whacking it

I think your suggestion, as strange as it may seem, has merit for member rollingradios - give 'em a good smack, especially near the connections. can't hurt, a smack on the receiver panel might help too

 

[noah katz]

yes and besides highlighting intermittent connections it's the most emotionally satisfying troubleshooting technique