Just built Fusion-8's. Tweeter side of one not working. Help? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 11 Old 05-18-2017, 08:14 PM - Thread Starter
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Just built Fusion-8's. Tweeter side of one not working. Help?

Speaker 1 works flawlessly. Speaker 2 has a non working tweeter circuit.

Swapped tweeters between speakers. Speaker 1 keeps working normally. Speaker 2 still has a non working tweeter.

I have the crossover PCB's. Double checked crossover in speaker 2, and everything is soldered appropriately. Checked quick connects to tweeter... plenty of wire inside the quick connects. But I also tried by just holding wires (outside of the quick connect) to the tweeter contacts. No difference.

Thing is, even if something was wired incorrectly I would expect to get SOME output. But right now I have nothing in that tweeter circuit. Kind of at a loss here, especially since the woofer works just fine on that speaker.

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post #2 of 11 Old 05-18-2017, 08:22 PM - Thread Starter
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I just measured 4 ohms at the tweeter output on the crossover board. Hmmmm.... but woofer output is fluctuating between like 55-60 ohms?? lol?




Edit: actually, it occurred to me that all I am measuring at the tweeter output on the PCB is a 4ohm resistor. (doh).

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post #3 of 11 Old 05-19-2017, 09:01 AM
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Sounds like you have an ohm meter - check impedance from from INP- to the (+) tweeter lug - should be zero; then from the mid board lead of CAP HI to the (-) tweeter lug - that should be less than 12 ohms (i think). If both those conditions are met, your most probable failure modes are an open CAP HI, or a shorted COIL HI. Best of luck!
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post #4 of 11 Old 05-19-2017, 10:54 AM - Thread Starter
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Quote:
Originally Posted by scotthal View Post
check impedance from from INP- to the (+) tweeter lug - should be zero
Yep, it's 0.


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then from the mid board lead of CAP HI to the (-) tweeter lug - that should be less than 12 ohms (i think).
If I'm measuring the right things.... 4.2 ohms.




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If both those conditions are met, your most probable failure modes are an open CAP HI, or a shorted COIL HI. Best of luck!

Not sure what this means exactly. Failed components on the board? Any way to test the cap or inductor?

Cap HI is reading 50.2 ohms. Inductor Hi is reading 0.3 ohms.
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post #5 of 11 Old 05-19-2017, 11:28 AM
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OK - if you've tested from top_of_board component leads to the actual speaker lugs (not the quick connect), then you've pretty much verified that the solder junctions are good. The only one you haven't tested would be the outside lead of CAP HI (adjacent to INP+). If that junction ain't bad, you may have a bad component - most likely CAP HI (the 2.2uF poly). Testing that would require a capacitance meter & popping a lead loose from the board.

Edit: Oops - 4.2 ohms? Would've expected something closer to 3 ohms, Try measuring the same points on your good board. If they don't match, you may want to double check the solder joints on the 16 ohm resistor.

Y'know, the last time someone reported problems with a DIYSG crossover circuit board, it turned out that they'd accidentally switched woofer : tweeter connections in just one of their speakers. Kinda comic.
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Last edited by scotthal; 05-19-2017 at 11:55 AM. Reason: More info
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post #6 of 11 Old 05-19-2017, 12:03 PM - Thread Starter
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OK - if you've tested from top_of_board component leads to the actual speaker lugs (not the quick connect), then you've pretty much verified that the solder junctions are good.
Yes, I am testing from the top of the board leads.

So this is actually 2.5 ohms when I measure at the tweeter's negative lug. Was 4.2 at the quick connect (tweeter not attached). Sorry.



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The only one you haven't tested would be the outside lead of CAP HI (adjacent to INP+).
One lead on the CAP HI next to the INP+. Where would I put my other lead? (Klein multimeter btw)





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Edit: Oops - 4.2 ohms? Try measuring the same points on your good board. If they don't match, you may want to double check the solder joints on the 16 ohm resistor.
I don't have a 16 ohm resistor. I have a 4 and a 12. Both of which are measuring 4 and 12 ohms respectively (at least from the top of the board leads)



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Y'know, the last time someone reported problems with a DIYSG crossover circuit board, it turned out that they'd accidentally switched woofer : tweeter connections in just one of their speakers. Kinda comic.
Meaning they had their woofer connected to the tweeter output, and visa versa? I wish that were the case. Cause if it were, I'd be getting some sound from the tweeter and could easily just switch it around.
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post #7 of 11 Old 05-19-2017, 12:16 PM
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My bad, misread the schematic. Thing is, with tweeter disconnected, measuring the DC resistance across the topside leads of either the 4 ohm or the 12 ohm resistor should give you roughly 3 ohms - the two resistors are effectively in parallel through COIL HI. Yr reading strongly suggests a bad solder junction on the 12 ohm resistor.
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post #8 of 11 Old 05-19-2017, 12:28 PM - Thread Starter
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3.2 ohms from the topside lead of 4ohm resistor (next to HI-) to INP-.

0.4 ohms from the topside lead of 12 ohm resistor (next to INP+) to INP-.


Reflowed solder connection on both ends of 12 ohm resistor. No change in the ohms.

Last edited by Rebel975; 05-19-2017 at 12:47 PM.
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post #9 of 11 Old 05-19-2017, 12:47 PM - Thread Starter
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Quote:
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My bad, misread the schematic. Thing is, with tweeter disconnected, measuring the DC resistance across the topside leads of either the 4 ohm or the 12 ohm resistor should give you roughly 3 ohms - the two resistors are effectively in parallel through COIL HI. Yr reading strongly suggests a bad solder junction on the 12 ohm resistor.


Seems you were right. After resoldering both ends of the 12ohm resistor the tweeter is working. Holy crap. Thanks for the help!
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post #10 of 11 Old 05-19-2017, 12:54 PM
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Awesome troubleshooting, scotthal.
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post #11 of 11 Old 05-19-2017, 01:14 PM - Thread Starter
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Awesome troubleshooting, scotthal.


Yes, I agree. Exactly the kind of help I needed. Very much appreciate it scotthal.
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