SDA-2 Tweeter (Dimensional H.F.'s)

ISLANDREAMER
ISLANDREAMER Posts: 15
edited August 2004 in Vintage Speakers
I noticed that the outer tweeter (Dimensional H.F. units) on each baffle of my SDA-2 does not emit any sound but when removed and tested on the inner tweeters (Stereo H.F. units), it does make a sound. My manual mentions of 2 fuses, one for dimensional and one for the stereo H.F. units near the speaker connection terminals but I don't see any "fast-blo" fuses on these speakers. Any advice is highly appreciated.
Post edited by ISLANDREAMER on

Comments

  • F1nut
    F1nut Posts: 49,711
    edited August 2004
    Welcome to the forum.

    You will find either the fuses or polyswitches, depending on the version of your SDA 2's on the crossover board. Remove the passive radiators from the front of each speaker to get access to the crossover.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • ISLANDREAMER
    ISLANDREAMER Posts: 15
    edited August 2004
    I took off the passive radiator and there are 2 crossovers. The crossover (top) not directly connected to the speaker terminals has a roll of copper wire behind it. Will these fuse look like a regular fuse with glass in the middle and metal caps on the end? I am clueless on what a polyswitch would look like. I certainly appreciate the assistance F1.
  • ISLANDREAMER
    ISLANDREAMER Posts: 15
    edited August 2004
    This is a thread from my last email. I need help in locating the fuse or polyswitch. Thanks.
  • F1nut
    F1nut Posts: 49,711
    edited August 2004
    I don't see any regular fuses in there and I'm only quessing about this one, but it looks like the polyswitch is the small blue device on the top crossover near the lower right hand edge.

    Since I'm not all that familiar with your speakers, I've forwarded this thread to Ken Swauger at Polk with the hope that he'll be able to help you further.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited August 2004
    As F1nut guessed, the poly switch is the small blue disk-shaped two-pin device on each of the circuit boards.

    Sometimes these switches will go bad due to age and/or electrical stress. Polk will provide an improved replacement part free of charge. Even though the other polyswitch is still working, I would go ahead and replace it.

    Contact Ken Swauger at polkcs@polkaudio.com.

    Prior to the polyswitches, glass fuses were used in earlier SDA models. These fuses were located on the binding post plate. Back when these speakers were made, Polk would insert a correction sheet into the old manuals until they were all used up rather that print a new manual with the correction.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • F1nut
    F1nut Posts: 49,711
    edited August 2004
    Thanks for chiming in Raife, I owe you a email. :)
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • ISLANDREAMER
    ISLANDREAMER Posts: 15
    edited August 2004
    Thanks for the tip DarqueKnight and F1Nut. I also emailed Ken Swauger at Polk and see if I have to mail out the crossovers or will I get the polyswitches and install them myself.:)
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited August 2004
    If you can use a soldering iron or if you have a friend who can use a soldering iron, it is a very simple procedure. It is not necessary to send the crossovers back to Polk.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • ISLANDREAMER
    ISLANDREAMER Posts: 15
    edited August 2004
    I have a soldering kit and I can do this myself. Just in case Polk can not mail me the switches asap, do you have any recommended speaker parts online stores? I've checked out Parts Express and they have a few made by Raychem with different ratings at $1.35 a piece.
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited August 2004
    Polk is usually quick about getting parts out. I would expect that the polyswitches would be shipped within a couple days of placing the order, unless they are out of stock. If they are currently out of stock, you might ask if there is an equivalent part available from another parts supplier.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • trixie_tracer
    trixie_tracer Posts: 2
    edited August 2004
    If my memory serves correctly, the poly switch was used to shut the whole crossover down to prevent overheating. Does the tweeter emit no sound? The SDA was designed to eliminate "crossover" from right channel to left, thus giving true "stereo" sound. I belive the second tweeter you mention is the one that gives this effect to the listener. I could be wrong, it's been over 15 years since I worked on them.
  • ISLANDREAMER
    ISLANDREAMER Posts: 15
    edited August 2004
    I decided to do a continuity test with my multi-tester on these polyswitches with the speakers powered up. What puzzled me is that all four polyswitches indicated continuity. I was expecting that two of the four will show no continuity. What's even more puzzling is that one of the outer (Dimensional H.F.) tweeter is now sounding but the other outer tweeter is still mute. Did that polyswitch for that tweeter reset (if possible)? Did I do the right check on these polyswitches?
  • trixie_tracer
    trixie_tracer Posts: 2
    edited August 2004
    Poly switch is triggered by heat. It is a short when measured at room temp, when heated up the poly switch "opens" like a fuse. When poly switch cools, it will go back to 0 ohms. Pretty cleaver, eh?
  • F1nut
    F1nut Posts: 49,711
    edited August 2004
    The polyswitch shuts down the tweeters, not the mid-drivers. My advice is to replacement all of them.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • dorokusai
    dorokusai Posts: 25,573
    edited August 2004
    Originally posted by trixie_tracer
    If my memory serves correctly, the poly switch was used to shut the whole crossover down to prevent overheating. Does the tweeter emit no sound? The SDA was designed to eliminate "crossover" from right channel to left, thus giving true "stereo" sound. I belive the second tweeter you mention is the one that gives this effect to the listener. I could be wrong, it's been over 15 years since I worked on them.

    Crosstalk...not Crossover :)
    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.