SDA SRS 2.3tl troubleshooting help

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Navy_Goat
Navy_Goat Posts: 375
in Vintage Speakers
I hope everyone is having a safe and happy holiday season.

A few weeks ago I lost a tweeter on the left side of my SDA SRS 2.3tl. No smoke or anything so I can not precisely say when it happened. I just noticed something sounded off one day. I did recently rebuilt the crossovers so before I just order a new tweeter I wanted to check the circuits. As it turns out the top and bottom teeters on the left side are bad.

I performed the troubleshooting measurements from the SDA Handbook pg 34-37.

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I do not see any specific measurements for the SDA SRS 2.3tl in the handbook. Looks to me like the first and third measurements are way too low. The measurements were the same for both sides so at least if I screwed something up I was consistent...

NOTE: I have a cheap multimeter so .2 ohms is about as low as it ever measures.

When I refreshed the crossovers I didn't deviate from the OEM values. I did pull the left side crossover to visually verify that everything is in the right place and it looks right to me.

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Can someone one verify what the SDA SRS 2.3tl measurements should be?

Plan is to order some new tweeters, but I would like to eliminate the crossover work as a cause so I don't just end up in the same boat again in a few weeks.
SDA SRS 2.3tl, SDA 1C, SDA 2B (TL mod), Reserve 200
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  • F1nut
    F1nut Posts: 49,794
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    What is the shiny stuff with the fingerprint in it between the small inductor and the 5.8uF?

    Simple way to test the left channel crossover.....swap it with the right.
    Political Correctness'.........defined

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  • Navy_Goat
    Navy_Goat Posts: 375
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    F1nut wrote: »
    What is the shiny stuff with the fingerprint in it between the small inductor and the 5.8uF?
    I don't know? I would assume it would be flux that I missed when cleaning the board after installing nearby components but it is not at all sticky. Its not nearly as noticeable as this picture makes it look. I will clean it off with some iso alcohol.
    F1nut wrote: »
    Simple way to test the left channel crossover.....swap it with the right.
    I will swap the two crossovers when I put everything back together which will help if I run into this problem again. Unfortunately at that point I will have brand new tweeters that will be installed. I was hoping to isolate the cause without breaking anything else.

    This morning I started checking the tweeters on the right side. I pulled the top and bottom and one of the two is measuring 52 ohms. At this point I think I may have just overdriven both sides at some point when I was a little aggressive with the volume.

    While I am at it I think I will pull all the drivers to make sure I have the wiring right.

    I believe the tweeters are attenuated at different levels. Which is the primary (most volume)?
    SDA SRS 2.3tl, SDA 1C, SDA 2B (TL mod), Reserve 200
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  • pitdogg2
    pitdogg2 Posts: 24,559
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    Tweeters primary is the top and they decrease to the bottom.
    Bottom is the most attenuated.
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  • Gardenstater
    Gardenstater Posts: 4,183
    edited December 2020
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    None of those measurements in that worksheet involve the tweeter circuits because the capacitors cannot pass DC current. Those 1st and 3rd measurements are just measuring the resistance of the 18awg, 16mH inductor and the associated wires and connections. The 2nd measurement should be 0 but your meter isn't zeroed so that reading you got is basically 0.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
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  • Navy_Goat
    Navy_Goat Posts: 375
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    Thanks @Gardenstater, @F1nut and @pitdogg2 for the help. After double and triple checking the wiring I installed the new RD0198s. They sound great again! Looking forward to incremental improvement as the new tweeters break in. I took this time to simplify the living room 2 channel rig. Now it is simple Marantz ND 8006 > Anthem TLP 1L > Parasound HCA 1500A.
    48djq9b1ad6a.jpg
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    SDA SRS 2.3tl, SDA 1C, SDA 2B (TL mod), Reserve 200
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