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Onkyo shuts off with Forte II speakers


Defacto

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Ugh..  Is it too late to return them?  Were you told by the seller they were functioning properly?  I know some here wouldn't mind the challenge of sorting out a problem like this - and perhaps you're among them - but it would drive me nuts. 

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2 hours ago, Defacto said:

This looks bad.

 

 

I would describe it more as scuffed or untidy.

 

Can you take a picture from the other side?  Perhaps the 110uf electrolytic capacitor has failed, but we can guide you through some further measurements.

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16 hours ago, Defacto said:

I have checked and rechecked for wire issues.

 

I reconnected the Klipsch R26F,am listening to them at 80 

and all is fine.

 

The ex-owner did replace tweeters and caps himself.

Perhaps he never plaid them loud and this could cause the issue?

 

3 hours ago, Defacto said:

One speaker shows 0.4 ohm resistance; the other shows 4 ohm.  I want to take a look inside before trying the wiggling.  I guess the 0.4 ohm speaker should be first.

 

Thank you all for your time and advice!  I'll take some pics of internals later today.

Good thing your amp has a protection circuit and was shutting itself down. Glad you found the culprit, so you can now pinpoint the fault.

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45 minutes ago, mboxler said:

 

I would describe it more as scuffed or untidy.  Can you take a picture from the other side?  

 

I assumed the bare pads could indicate lack of solder connection.

 

I'm glad to take more pictures if these do not suffice.

 

 

Forte II Xover Back 2.jpg

Forte II Xover Back.jpg

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1 hour ago, ODS123 said:

Ugh..  Is it too late to return them?  Were you told by the seller they were functioning properly?  I know some here wouldn't mind the challenge of sorting out a problem like this - and perhaps you're among them - but it would drive me nuts. 

 

lol it's not a problem, it's a chance to learn! :) 

I assume most person to person sales come with a taillight warranty.    

It could be he never played them above a moderate volume.

  

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.4 ohms, yup that is definitely the problem right there.

 

Not gonna lie whoever worked on these did an absolutely horrendous job, just awful.

 

You aren't looking for bad solder joints or connections, .4 ohms means there is a short so you want to look for two things touching that shouldn't be. I would start around C3 as that just looks like a short waiting to happen.

 

Leave your meter connected while wiggling each components and their leads and watch the meter to go back to normal resistance. That will at least pin point where the issue is.

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32 minutes ago, captainbeefheart said:

.4 ohms, yup that is definitely the problem right there.

 

The probes I used were defective it seems.  Another set of probes show both speakers around 7 ohms.  Sorry for the bad info.

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3 minutes ago, Defacto said:

 

The probes I used were defective it seems.  Another set of probes show both speakers around 7 ohms.  Sorry for the bad info.

 

Or moving the crossovers around has temporarily fixed the issue and you are now reading both correct resistances.

 

 

I still recommend with the better probes to connect the meter and do the wiggle test, you won't damage anything. Does your meter auto-range or do you have to manually choose your ranges?

 

Have you looked at the wiring on the drivers themselves?

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I tried moving things with no change.  I have no other speaker wires.  I could switch them. 

 

I wonder if hooking the Fortes up one at a time and trying volume 80 is a good tactic?

 

Pics of driver and magnet wires :

 

 

Forte II D1.jpg

Forte II D2.jpg

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@captainbeefheart  @Defacto I checked the Onkyo TX-NR656   Amplifier specs , it's rated at 100wpc Stereo/ 8 Ohms ,  it could very well be that the Amplifier is simply clipping once the Volume hits 80  ,I am not saying the crossover work is excellent , except that the Onkyo amp's distortion is too high  , when it reaches 80 on the dial  .

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Just FYI. I ruined one of those 80 watt pc Onkyo amps by listening to Toccata in D Minor with bass turned up. Awful noise came out and the amp shut down. Being new to me I did it again and then figured out that wimpy amp could not push a Forte if bass was turned up.

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12 minutes ago, Dave A said:

with bass turned up

"On a Forte" is how the sentence should have ended. I tried going back and editing the sentence and soon got a basic to much time has passed for you to edit your comment. If I read that right that is super good news.

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57 minutes ago, 001 said:

@captainbeefheart  @Defacto I checked the Onkyo TX-NR656   Amplifier specs , it's rated at 100wpc at 8 Ohms ,  it could very well be that the Amplifier is simply clipping once the Volume hits 80  ,I am not saying the crossover work is excellent , except that the  amplifier's distortion is too high when it reaches 80 on the dial  -

 

I downloaded the service manual and it states

 

FTC

Both channels driven same time into 8 ohms minimum 100 watts @ .08% THD 20-20kHz

 

Surround sound mode

170 watts into 6 ohms @ .9% THD 1kHz

 

IEC

160 watts x7 into 6 ohm load @ 1% THD 1kHz

 

Effective maximum power

175 watts x7 into 6 ohms @ 10% THD 1kHz

 

 

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24 minutes ago, captainbeefheart said:

 

I downloaded the service manual and it states

 

FTC

Both channels driven same time into 8 ohms minimum 100 watts @ .08% THD 20-20k

 

 

 I read the specs and initially , I had the same reaction  ,  but the amp may also be clipping in Stereo mode at 80%  on the dial  , as Protection circuits  kick in ,  it would be interesting to  do the test with another pair of speakers , and if the same happens  ,  then we could rule out the speakers -

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5 hours ago, Defacto said:

 

The probes I used were defective it seems.  Another set of probes show both speakers around 7 ohms.  Sorry for the bad info.

 

Even this doesn't seem correct to me.  Isn't the Forte II K-25 woofer 4 ohms?   I just read another post that said the DC resistance at the speaker terminals measured 4.3 ohms, which sounds right if you add in the DC resistance of the inductor.  He also noted that the impedance of the speaker drops below 4 ohms between 100 and 200hz.  That's a lot of current!

 

Might be interesting to remove the wires from the woofer and measure the DC resistance across the K-25 terminals.

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