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Discussion Starter #1
Sony SS-MF550H speaker.

Problem:

SpeakerProblem.jpg

Which setting do I use and where do I put the Digital Multimeter ends to test if Caps are bad or if tweeter is blown? How do I find out what to replace?

SpeakerFlipSide.jpg
 

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Elite Shackster , HTS Moderator Emeritus
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Usually blown drivers sound bad, but some sound comes out.

Unwire it from the amp and check resistance across the driver terminals. Each should have some resistance (4 to 8 Ohms or so). If any measure is low (less than 1 Ohm) then you might have a dead short capacitor. Similarly, you could have a fully dead-open capacitor that isn't passing signal. If there are any resistors in series with the driver they might have failed open, so no completed circuit from the speaker terminals to the driver terminals.

That's all I can think of for now. Keep us posted and more people may chime in.

If you want, I can move this to the DIY Speakers forum, where you might get some more responses.

Good luck,
Anthony
 

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Elite Shackster , HTS Moderator Emeritus
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Also, the caps should have some markings on them. Disconnect the leads from the driver and you can measure the cap directly with some multimeters. My $30 Radio Shack one will measure caps, but the $200 Fluke at work is much better. But if your caps are so bad they aren't working at all, the cheap meter would tell you as much.
 

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If you want to check to see if the drivers are OK, temporarily bypass the caps and turn the volume way down low. If sound comes out then you know the drivers are OK, but again, don't turn the volume up much at all or you will blow the tweeter.

I assume that there is no fuse on the mid/tweeter?
 

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Possible internal wire/s disconnected
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The fact that both the tweeter and the midrange speakers are both not making any sound may indicate a loose or disconnected wire/s. I would check the internal wiring to the speaker's binding posts. Each driver has it's own crossover filter cap, therefore having both fail at the same time would be unlikely.

You could also compare resistance measurements from your other working speaker with the faulty one to locate something different and the possble defective component.


Read more: http://www.hometheatershack.com/forums/system-setup-connection/66171-possible-internal-wire-s-disconnected.html#ixzz2N9RZPRRP
 

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Discussion Starter #6
It doesn't seem to be internally disconnected and there is zero sound coming out. I have a True RMS Digital Multimeter Radio Shack 22-174B, where do I put the red and where do I put the black and what do I turn the Digital Multimeter to?

Moderator, yes you can move thread where it would get more responses, thank you!
 

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It doesn't seem to be internally disconnected and there is zero sound coming out. I have a True RMS Digital Multimeter Radio Shack 22-174B, where do I put the red and where do I put the black and what do I turn the Digital Multimeter to?
Have you measured the resistance (on ohms scale) across the drivers or between the internal connections and the binding posts? Compare the "good" speaker measurements to the "bad" speaker. Look for large differences between the two measurements.

BTW has the speaker been tipped over or dropped? Is there any physical damage to the magnet structure? Does the midrange cone move freely if gently pressed with your fingers? Maybe the speakers are internally binding and therefore unrepairable if mishandled.
 

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It doesn't seem to be internally disconnected and there is zero sound coming out. I have a True RMS Digital Multimeter Radio Shack 22-174B, where do I put the red and where do I put the black and what do I turn the Digital Multimeter to?

Moderator, yes you can move thread where it would get more responses, thank you!

Turn the meter to Ohms on the lowest scale. Start by putting the meter probes on the terminals of the mid and tweeter. Probably a good idea to disconnect the wiring to them before measuring, since the crossover could have a resistor in parallel. A reading of 10 ohms or less, or really anything other than "infinite" resistance, means that the voice coils on the drivers are OK.

If your meter measures capacitance, you can check the capacitors in the crossovers as well, but be sure to disconnect the wiring to them first.
 

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Discussion Starter #9
After disconnecting the speaker from the amp, and doing this, I get 8.6 Ohms for both:

8.6ohms.jpg





Are you saying disconnect this and this next:

Disconnect.jpg


If not, what should I measure next, using which settings on this:

RadioShackDigitalMultimeter.jpg


This is what we are dealing with:
 

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Plain ole user
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Are there any fuses or resistors in the line. It is almost impossible to get no sound due to bad caps. The sound would be higher or lower, but it would not make it zero.
 

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Discussion Starter #12
Thank you for your reply.
Are there any fuses or resistors in the line. It is almost impossible to get no sound due to bad caps. The sound would be higher or lower, but it would not make it zero.
As you can see there is nothing physically present between the outside speaker connection and the entire assortment of all the wires:


 

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Discussion Starter #14
Yes. You see how the Black/Red is going to the large Bass Driver cone and then in the picture below, from that large Bass Driver cone the Black/Yellow wire first appears and starts to go toward the non-working Mid Driver and Tweeter cones?

I would be grateful if you could tell me what to test next and how.
 

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If you have a volt meter I would check the impedance of the mid and tweeter coils to make sure they aren't blown. If you don't have a meter I would suggest turning the bass to it's lowest setting and, with music playing at a low level, put a link across the cap going to the mid driver to see if you get any sound.
Alternatively, again with the bass turned down and at a low level, connect the banana plugs directly to the mid speaker terminals.
Let us know how you get on.
 

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Discussion Starter #16
Thank you. Post #9 of this thread has a picture of my Digital Multimeter. Post#9 also shows, after disconnecting the speaker from the amp, how I got 8.6 Ohm measurements.


Can you tell me where to place the red & black and what to measure next, using which setting on the pictured DMM?
 

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Disconnect one wire from each speaker and measure again across the terminals of each.
 

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Is this what you were asking: 8.6 Ohms as pictured but Nothing if this black wire is disconnected.
When you do that try to put your ear next to the mid/tweeter drivers and if you hear a low crackling sound coming out of those drivers they are probably good. Also try to make a continuty test between all wires inside the cabinet it could be also a bad crimping wire.
 

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Discussion Starter #20
If you look at this first, you have the black/red wire successfully bringing the signal in. Then it is split off with black/yellow wire which are the only two wires connecting the non-working cone above it:

SpeakerProblem4.jpg


SpeakerProblem5.jpg


So it has to be the black/yellow wire or the blue resistor that is the cause, right?

[As to the one above it, the blue/black wire is separately either not bringing the signal in to the top cone or it also has a bad resistor?]
 
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