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  1. #1

    Stereo Reciever problems

    Hello there folks,
    My quest for info lead me to this site.
    I am as green as grass when it comes to trouble shooting these electronic devices,let alone hooking up all the gadgets in the proper places without getting all frustrated and
    Maybe one of you electrical gurus can help me out.

    I got a JVC model RX-703VBK digital surround system reciever.

    Here is my problem.

    The system has worked fine for many yrs,but last yr 1 of the speakers quit operating,and a few months ago the other one quit also.
    The speaker boxes(came with the system) are 2 towers with 3 speakers each coming to a single 2 wire lead.
    each box has power handling capasity 125 w, with music 210 W 8 ohm.

    There are 2 seperate speaker jack clusters on the back of the reciever.
    1 cluster has room for 4 speakers,2 jacks left and 2 right enclosed in a lined area that says (speakers) ( here is where the towers originally where hooked into)

    The other speaker jack cluster has room for 2 speakers and and is in a lined area that says (surround speakers).

    All jacks say speaker impedance 8 to 16 ohms.

    After fooling around some trying to make the thing work again,i plugged the speakers in the (surround speaker) jacks and after activating the surround button on front the system makes finally sound again.

    my question is how do i properly test the jack output of the other speaker jacks to figure out what made the speakers quit there.

    I got signal on all jacks with my digital multimeter but dont know what values are normally read, AC , DC or Ohms ,and what values are supposed to be there.
    And how do i test the speakers for in or output.either

    Sorry for the long post,but i wanted to be as informative as possible.

    Thanks

  2. #2
    To begin with, a DVM isn't going to tell you crap, except a shot speaker and there you will read zero ohms for a shorted voice coil or infinite for an open one.

    Really the quickest way is to substitute speakers that you know work.

    You shouldn't read any DC voltage from any output, because they are all transformer coupled. The only way to measure the out put is with an oscilloscope.

    So why did speakers die? I have no way of knowing.

    It kinda sucks when you buy a matched system and stuff goes prematurely bad, but Let The Buyer Beware is sticking in my craw right now, so get back if you figure it out or have more questions.
    'I think my intimate relationship with electronics started as a child when I was playing with a screwdriver and a wall plug, Doc, and...'

  3. #3
    Quote
    Quote: penniesfromheaven
    View Post
    To begin with, a DVM isn't going to tell you crap, except a shot speaker and there you will read zero ohms for a shorted voice coil or infinite for an open one.

    Really the quickest way is to substitute speakers that you know work.

    You shouldn't read any DC voltage from any output, because they are all transformer coupled. The only way to measure the out put is with an oscilloscope.

    So why did speakers die? I have no way of knowing.

    It kinda sucks when you buy a matched system and stuff goes prematurely bad, but Let The Buyer Beware is sticking in my craw right now, so get back if you figure it out or have more questions.
    My speakers aint shot,they are working fine in the surround mode and surround jacks,just not anymore in the normal speaker jacks they where plugged in before.

    Both speakers measured between 6.7 and 8.3 ohms with the DVM.(not bad for DVM not able to tell crap).

    I cant say the system went prematurely bad either,i have used it for 15 yrs daily

    I just want to find out how to properly test the reciever speaker jacks output and what the values are supposed to be,and if bad ,if it can be fixed without spending a fortune.

    Sure, i can buy new ,but dont want to unless no other option exists.

    I try to streeeeeeetch the $ to the limmit.

  4. #4
    Thanks for the help folks,its apriciated

  5. #5
    I hear ya. But the 6.7 and8.3 ohms reading is just the DC resistance of the speaker coils and crossovers, if any, in the speakers, not the impedance. It doesn't tell much.

    Without the speakers connected measure the DC and AC voltages at the outputs. If the outputs are transformer coupled you should get almost no DC and a jumping around amount of AC; You won't get a steady reading, it will look like the meter is going nuts. Depends somewhat on the sensitivity of the meter. If they are direct coupled (transformerless) You will get a higher DC reading, maybe up to 10 volts or more, and the same AC reading I described above. There are many more output configs, and meter readings will still be indecipherable, except to tell you that SOMETHING is doing SOMETHING. But unless you open up the box and test componant by componant, you really can't know if what the meter says is true.

    Problem is, you can't really tell if the meter is really seeing an AC voltage or if it's reading your body capacitance or something. That's why I would use a scope, that's all.

    Sorry I can't be of more help.
    Last edited by penniesfromheaven; 21st Sep 2009 at 04:33.
    'I think my intimate relationship with electronics started as a child when I was playing with a screwdriver and a wall plug, Doc, and...'

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