Fixing a frozen MW6500 in TN or AR

mattkiefer
mattkiefer Posts: 6
edited October 2012 in Vintage Speakers
Hi folks,

I was ecstatic to find a pair of Monitor 10As at a yard sale this past weekend. Unfortunately, one of the midbass drivers, a MW6500, is frozen. I have never done any DIY speaker stuff, so fixing this is probably beyond me, but I know a number of people have a rig to do it. Anybody within a few hours of Memphis Tennessee who could fix this for less than the price of an eBay replacement? I can't view the for sale forum since I'm new, so I'm also open to info on where I could find a replacement from a fellow Polk enthusiast. Thanks for any help!
Post edited by mattkiefer on
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  • naturallight
    naturallight Posts: 689
    edited September 2012
    My "guess" would be the driver is probably 'Fried"...which means it's unfixable. I don't know if Polk makes the replacement speaker or not. But you should call them and see. If not, you need to look on Ebay and see what you can find.
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  • mattkiefer
    mattkiefer Posts: 6
    edited September 2012
    Thanks for the input - if it's truly fried I'm sure you're right. I figured that it was case of magnet shift, since this is the driver that I've read has that problem a lot. Any way for me to test this?

    And while I'm asking questions, can someone point me to exact directions for where to epoxy on the other drivers so this doesn't happen?
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  • naturallight
    naturallight Posts: 689
    edited September 2012
    Well..magnet shift..not so much of a problem, as the driver just being fried, from being abused. Since you got it at a yard sale..my guess it's fried. You can test..pull the driver out, check the ohms on it. If it's 0 it's toaste.
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  • Mystery
    Mystery Posts: 2,546
    edited September 2012
    mattkiefer wrote: »
    Thanks for the input - if it's truly fried I'm sure you're right. I figured that it was case of magnet shift, since this is the driver that I've read has that problem a lot. Any way for me to test this?

    And while I'm asking questions, can someone point me to exact directions for where to epoxy on the other drivers so this doesn't happen?

    If the driver makes sound but not moving inside/out, then voice coil is okay and magnet shift is the issue.
    You can also confirm with a multimeter.

    Check this thread out: http://www.polkaudio.com/forums/showthread.php?132835-How-much-Epoxy-%28JBWeld%29-needed-for-a-pair-of-speakers

    Here is a picture:
    http://i1138.photobucket.com/albums/n534/Trekker-1701/IMG_0829.jpg

    Klipsch RB81, KG3.5, B&W DM602.5, Polk.
    Subwoofers: Klipsch RW10, Triad ProSub Bronze.
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  • naturallight
    naturallight Posts: 689
    edited September 2012
    I "presume you get NO sound out of this driver...IS the right or wrong??????
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  • mattkiefer
    mattkiefer Posts: 6
    edited September 2012
    I don't have a multimeter, but I'll try to borrow one. I don't think I hear anything when I put my ear next to this speaker. The lady who sold them to me didn't seem the abusing type, so I just figured it was magnet shift. If it's not and the driver is truly dead, I'll start looking for a replacement.
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  • TNHNDYMAN
    TNHNDYMAN Posts: 2,145
    edited September 2012
    Usually you can look at the magnet and tell it's no longer centered. Also when frozen you will not be able to get the cone to move freely in and out. Almost impossible to fix, so I'd recommend looking online for a replacement. Probably a mw6500 driver, but you can get a very similar replacement from polk if you call the customer service #.

    Stay around awhile and enjoy the forum and a member may offer a spare for sale to you or just pay the going rate on ebay and call it a day. I had a few extras but they have since been sold or traded for other gear and need what I have on hand for projects on my 10's this winter.
    2-ch System: Parasound P/LD 2000 pre, Parasound HCA-1000 amp, Parasound T/DQ Tuner, Phase Technology PC-100 Tower speakers, Technics SL-1600 Turntable, Denon 2910 SACD/CD player, Peachtree DAC iT and X1asynchorus USB converter, HSU VTF-3 subwoofer.

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  • nspindel
    nspindel Posts: 5,343
    edited September 2012
    you should be speaking to saftgeek, the new resident expert in repairing these drivers!
    Good music, a good source, and good power can make SDA's sing. Tubes make them dance.
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  • Mystery
    Mystery Posts: 2,546
    edited September 2012
    mattkiefer wrote: »
    I don't have a multimeter, but I'll try to borrow one. I don't think I hear anything when I put my ear next to this speaker. The lady who sold them to me didn't seem the abusing type, so I just figured it was magnet shift. If it's not and the driver is truly dead, I'll start looking for a replacement.
    If you can't hear anything, then it's done.

    When you push the speaker, does it move freely?
    If it does, then magnet is not shifted, it's the voice coil that's gone.
    If it does not, then both voice coil and magnet are bad.

    Klipsch RB81, KG3.5, B&W DM602.5, Polk.
    Subwoofers: Klipsch RW10, Triad ProSub Bronze.
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  • mattkiefer
    mattkiefer Posts: 6
    edited September 2012
    No movement. How could a non-moving speaker produce sound (in the case of only the magnet bad)?
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  • Mystery
    Mystery Posts: 2,546
    edited September 2012
    I have a frozen driver from S8 that looks perfect physically and also makes sound but the sound is like coming from a much smaller speaker as the cone cannot move due to magnet shift.
    It vibrates but not enough to feel it's moving.
    Here is the post:
    http://www.polkaudio.com/forums/showthread.php?132835-How-much-Epoxy-(JBWeld)-needed-for-a-pair-of-speakers&p=1781699&viewfull=1#post1781699

    BTW, buy a simple multimeter from walmart or harborfreight.
    They cost less than $5 but will confirm whether a driver is open/bad or not.

    Klipsch RB81, KG3.5, B&W DM602.5, Polk.
    Subwoofers: Klipsch RW10, Triad ProSub Bronze.
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  • gdb
    gdb Posts: 6,012
    edited September 2012
    http://www.polkaudio.com/forums/showthread.php?79649-DIY-magnet-re-centering-info&highlight=repair+magnet

    http://www.polkaudio.com/forums/showthread.php?135716-Let-s-Try-to-Fix-a-MW6511-Damaged-in-Shipping...
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  • mattkiefer
    mattkiefer Posts: 6
    edited September 2012
    Another newb question: when I pulled the driver to see what model it was, the two wires were soldered on. To undo this is it best to use a soldering iron to melt the connections, or do folks just cut the wires?
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  • dorokusai
    dorokusai Posts: 25,577
    edited September 2012
    nspindel wrote: »
    you should be speaking to saftgeek, the new resident expert in repairing these drivers!

    Uhhhhh, ok. That might be a bit much Nspindel.
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
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  • TNHNDYMAN
    TNHNDYMAN Posts: 2,145
    edited September 2012
    mattkiefer wrote: »
    Another newb question: when I pulled the driver to see what model it was, the two wires were soldered on. To undo this is it best to use a soldering iron to melt the connections, or do folks just cut the wires?

    I'd cut the wire near the terminals since it's toast anyways. When you find a replacement you can put new ends on the wire or solder directly your choice.
    2-ch System: Parasound P/LD 2000 pre, Parasound HCA-1000 amp, Parasound T/DQ Tuner, Phase Technology PC-100 Tower speakers, Technics SL-1600 Turntable, Denon 2910 SACD/CD player, Peachtree DAC iT and X1asynchorus USB converter, HSU VTF-3 subwoofer.

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  • Saftgeek
    Saftgeek Posts: 114
    edited September 2012
    Wow... I'm an expert!!! Thank you Mr. Nspin. If you find out that the speaker is indeed shifted and not fried I'd be happy to take a swing at it. All it would cost you is shipping. As far as the driver not moving, mine had shifted just enough where the voice coil was rubbing. At loud volume you couldn't hear it, lower volumes it was beyond annoying. Two days and about 4 mixed drinks later and I actually got my speaker back into working order. It sounds great now. PM me once you figure it out. I'm in MO so shipping won't break the bank. Keep in mind I am not a professional and I'm only offering because I was right where you are at less than a month ago. I can't screw it up any worse if it's not working.

    Mr. doro - I'm thinking a bit much too!

    -Saftgeek
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  • dorokusai
    dorokusai Posts: 25,577
    edited September 2012
    Saftgeek - That sounds mighty fine to me man, mighty fine :cheesygrin:
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
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  • mattkiefer
    mattkiefer Posts: 6
    edited October 2012
    Hi folks. Work caught up with me for a few weeks, but I finally pulled the driver and measured the ohms across the two tabs with a multimeter. I'm surprised at how bad I am at understanding this, but I think I got a reading of zero - so the driver is fried?
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  • ambiophonics
    ambiophonics Posts: 726
    edited October 2012
    Make sure your multimeter is set to a low range to measure the resistance - probably the 200 ohm range would be fine. I would expect resistance readings of about 6.5 ohms for an 8 ohm driver and 3 ohms or so for a 4 ohm driver. If your readings are very much above or below these numbers your voicecoil has either opened up or gone short.
    2 Channel - Polk SDA-2BTL, Carver TFM-35, Peachtree iDAC, Qobuz streamed via Episode Lynk using bubble UPnP server
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  • pitdogg2
    pitdogg2 Posts: 25,446
    edited October 2012
    there have been a slew of mw6500's on ebay as late i would go that or call Polk CS and get some new drivers and call it a day.
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  • rdozz
    rdozz Posts: 24
    edited October 2012
    I just picked up a MW-6500 on ebay for $22.50 plus $8.00 for shipping.

    Here is a pair for $29.00 but the shipping looks high at $18.00.

    www.ebay.com/itm/POLK-AUDIO-MW6500-Woofers-for-Monitor-10-Monitor-7-Monitor-12-SDA-/230861762624?pt=Speakers_Subwoofers&hash=item35c06ef040
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