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  1. #1
    Member Vintage Nut's Avatar
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    120 Ti Midrange Failure

    One of the midrange drivers in my pair of 120ti speakers has died. Sucks 'cause it was the one of the two that had a perfect dome - lol. Anyway, I think the crossover may be damaged too, because when I swapped the 104h-1 drivers between left and right to test them, the good one only works in it's original cabinet. I'm not sure how to test the crossovers aside from hooking a speaker up to them. I don't even know how to test the drivers properly with a hand-held tester. The bad 104h-1 does make a little noise, but it's barely audible. Anyway, I guess my question is how do I test the crossover before I start looking to replace it? And how do I test drivers? I do have a multi-meter tester.

    Also, if I decide to run a pair of 104h-2 drivers, as they are more readily available, would they sound good? I've had the 120 Ti speakers since new in 1990 and have ALWAYS LOVED them.
    Sony N55ES (2), E1000ESD, C85ES - JBL 120Ti | Onkyo TX-SR605 - JBL L830 (4), LC1 (1) | Dell - Pioneer SX-750 - JBL 4406

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    Member Vintage Nut's Avatar
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    Just to quickly clarify, the bad 104h-1 does NOT work (aside from faint sounds) in either cabinet. Only the good 104h-1 works in the cabinet it came in.
    Sony N55ES (2), E1000ESD, C85ES - JBL 120Ti | Onkyo TX-SR605 - JBL L830 (4), LC1 (1) | Dell - Pioneer SX-750 - JBL 4406

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    Senior Member rdgrimes's Avatar
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    Have you tried checking DC resistance on the bad driver? The 104 should read 3.8-4.6 ohms.

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    Member Vintage Nut's Avatar
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    Just tested: 1.0 on bad driver and 4.4 on good driver. Is that something that can be repaired or should I just replace it?

    Also figure mr crossover is bad. How do I test it with a meter and can it (normally) be repaired?
    Sony N55ES (2), E1000ESD, C85ES - JBL 120Ti | Onkyo TX-SR605 - JBL L830 (4), LC1 (1) | Dell - Pioneer SX-750 - JBL 4406

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    Probably easier to replace. there are a few on ebay now for a reasonable price.

    Allan

  6. #6
    Senior Member rdgrimes's Avatar
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    Quote Originally Posted by Vintage Nut View Post
    Just tested: 1.0 on bad driver and 4.4 on good driver. Is that something that can be repaired or should I just replace it?

    Also figure mr crossover is bad. How do I test it with a meter and can it (normally) be repaired?
    Given the 1u measurement, it's possible that something in the XO got cooked. Yes that can be repaired. A visual inspection of the mid-freq components in the XO may reveal something. Schematic is HERE.

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    Member tarior's Avatar
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    Fortunately, the 104H is rebuildable.

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    Member Vintage Nut's Avatar
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    Quote Originally Posted by rdgrimes View Post
    Given the 1u measurement, it's possible that something in the XO got cooked. Yes that can be repaired. A visual inspection of the mid-freq components in the XO may reveal something. Schematic is HERE.
    Thanks for the help. Here's a shot of the N120 XO. My eye is not trained to see anything wrong, other than the brownish coloring on one of the white blocks. But, it looks to me like that block is actually connected to the 044ti tweeter. Can I test things with the multimeter? Maybe I'll just find a replacement.

    http://i922.photobucket.com/albums/a...0/20022c1c.jpg
    Sony N55ES (2), E1000ESD, C85ES - JBL 120Ti | Onkyo TX-SR605 - JBL L830 (4), LC1 (1) | Dell - Pioneer SX-750 - JBL 4406

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