RM30 Trouble

jkf
jkf Posts: 3
edited March 2010 in Troubleshooting
My dog knocked over one of my RM30 speakers. No sound. Is there a way to trouble shoot to determine the problem. The same thing happened once before and I was able to order and replace a part. Thanks for any help.
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited March 2010
    jkf wrote: »
    My dog knocked over one of my RM30 speakers. No sound. Is there a way to trouble shoot to determine the problem. The same thing happened once before and I was able to order and replace a part. Thanks for any help.
    Welcome to CP JKF!

    The RM30 is typically an 8 ohms nominal impedance speaker and the audio signal is fed through its crossover. Using a multimeter (ohmeter) and measuring at the posts (with the straps on) you should see approximately 3.5 ohms. Since no sound at all is coming from either tweeter and driver, you will more likely read an open or at least a much higher value. If so...

    If your speaker is still on warranty and-or if you are feeling unsecure about opening the enclosure call Polk CS as they will provide you with outstanding service and lead you in the right direction.

    If you are eager to troubleshoot the speaker your self, here is how I suggest you proceed:

    1. Remove your grill...

    2. Locate and remove the 12 screws holding the plastic front speaker front plate...

    3. Now, CAREFULLY remove the front plate (CAREFULL! The tweeter is attached to the front plate)...

    4. Carefully remove the connections from the tweeter and put the front plate aside...

    5. Now, you must carefully remove the 4 screws of the bottom driver and disconnect the 2 wires in order in order to be able to access the RM30's crossover which is located under the white isolation material...

    6. Inspect the crossover for physical damage along with the internal wires (IE: broken connections at the crossover)...

    7. Using your multimeter (ohmeter) if you measure at the post with only one driver connected (bottom driver is still disconnected) you should read approximately 7 ohms. If you connect the second driver, you should read approximately 3.5 ohms (if you noticed, wires going to the drivers are in paralell from the driver board connection). Those readings proves a good connection from the posts through the crossover to the speaker...

    8. The connections to the tweeter are High impedance from the crossover and then the path is somewhat hard to read. Usually (with tweeter disconnected) Using the meter at the highest impedance range, I will invert the meter leads in order to find the right polarity to check movement on the meter (capacitor charging). Once the meter movement stops, the capacitor is fully charged. If you invert the leads again, the meter should go up again charging the capacitor on the opposite side. However, this does not fully prove this portion of the crossover to be fully operational.

    9. If the above readings are not seen but you rather are seeing open circuit and you have not found or resolve the problem yet, contact Polk for assistance providing with as much details as possible on your findings as your crossover may be defective!

    Good luck!
    TK
    DARE TO SOAR:
    “Your attitude, almost always determine your altitude in life” ;)
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  • RuSsMaN
    RuSsMaN Posts: 17,987
    edited March 2010
    Ok, TK, member of year? Did I miss the ballot?

    :D

    Cheers,
    Russ
    Check your lips at the door woman. Shake your hips like battleships. Yeah, all the white girls trip when I sing at Sunday service.
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited March 2010
    RuSsMaN wrote: »
    Ok, TK, member of year? Did I miss the ballot?

    :D

    Cheers,
    Russ
    Simply an humble Polk member but you can't keep an old technician from digging into his toys (I have 6 RM30s) 2 of them are older and I can't refrain my self to go straight to the buggers heart (open them) to satisfy my curiosity :o Afterall, the name is TECHNOKID, right ;) However note that whenever I dare offer humble technical help, I always make sure to refer the OP to Polk CSR since my info may not always be right :o

    Cheers!
    TK
    DARE TO SOAR:
    “Your attitude, almost always determine your altitude in life” ;)
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  • [Deleted User]
    [Deleted User] Posts: 7,658
    edited March 2010
    Nice work, TK! Very helpful...!
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  • Toolfan66
    Toolfan66 Posts: 17,240
    edited March 2010
    as already said TK,that was good on you, good Karma going your way.:)
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  • jkf
    jkf Posts: 3
    edited March 2010
    Thanks for the excellent advice, TK.
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited March 2010
    Jkf, once you have found and fixed the problem please report back on your thread as it may be of use to other members. I have no doubt that with Russ and Kenneth looking over your shoulder that a solution will be quickly found.
    as already said TK,that was good on you, good Karma going your way.
    TOOLFORLIFEFAN, thanks for the kind words :) Like many of us on this board, Karma is always welcome :).

    Cheers!
    Tk
    DARE TO SOAR:
    “Your attitude, almost always determine your altitude in life” ;)
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  • jkf
    jkf Posts: 3
    edited March 2010
    Hey TK--I followed your steps, but without the ohmeter. Saw no damage. When I hooked the speaker back up, it had sound. It sounds like the fall damaged the top driver. I'll order one from Polk CS tomorrow. Once again, thanks for your excellent advice.
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited March 2010
    jkf wrote: »
    Hey TK--I followed your steps, but without the ohmeter. Saw no damage. 1. When I hooked the speaker back up, it had sound. 2. It sounds like the fall damaged the top driver. 3. I'll order one from Polk CS tomorrow. Once again, thanks for your excellent advice.


    Just to make sure we understand what you are telling us:

    1. When you hooked-up which speaker? Top or bottom?

    2. Can you explain how you draw your conclusion? Was the bottom driver the only one that worked? How about the top and the tweeter?

    3. Before you order any replacement, have you at least swapped the driver connections? No need to remove the top driver, simply move the bottom connecting wires to the top and you can also do the same for the bottom one by installing the top driver connections to the top driver.

    ISOLATE EACH DRIVERS:

    Since you have proven that some of the drivers are working disconnect them all and then proceed to test one driver at the time. Swapp wiring around each drivers.

    Your next step would be to test 1 driver at the time with the tweeter always connected. You can still swap wiring for the drivers.

    Your last step would be to connect all drivers along with the tweeter and see what happens.

    If for example you loose sound only when the top driver is connected, that driver maybe shorted however I wouldn't jump to promptly to that conclusion since the Xo isn't fully ruled out thus the wiring swapping to isolate the problem.

    NOTE: If you don't have or can borrow a multimeter, a toner might be of help at this point if you own or can borrow. Injecting a tone at the woofer should be audible or the driver could be shorted. With you tone still injected you could check the drivers for continuity by shorting both terminals of the driver. If the driver coil is open anywhere you will still hear the tone. On the opposite, if the coil is good, the tone will stop and no longer be heard.

    Cheers!
    TK
    DARE TO SOAR:
    “Your attitude, almost always determine your altitude in life” ;)
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