SDA-2 Questions

dbratton

I have a pair of SDA-2s that I bought (practically stole) from a pawn shop. I have had them for a while now, and I love them. Recently, I had to move them and blew a mid range speaker. My question is about how this happened. I disconnected the speakers from the amp which was unplugged. I then disconnected the speaker cables from the speakers. After that I unplugged the interconnect cable from the left speaker and there was a loud pop and hum from the right speaker. I hurriedly pulled the cable out of the other speaker and the noise stopped, but my mid-range speaker has not worked since then. (I am looking into getting a replacement part.)

I know that the cable leads did not touch, so nothing shorted. My questions are what caused this? Is there some sort of capacitor inside these loudspeakers? How on earth was there any power available to the speakers to cause the pop?

Thanks for any info.

F1nut

Got me.

dcoil

Wow, there are usually some pretty good sized caps on those crossovers. But it really sounds like you did everything correct. I've been on this forum long enough to know that if F1 says 'got me', there probably isn't a good answer.

inspiredsports

When you say replacement part, do you mean the 6.5" driver?

The reason I ask is I'm wondering if there is a problem in one of the crossovers (or connections) that could cause it to happen again. As above, I think this must be a something that has not happened before.

Tour2ma

dbratton wrote: »

After that I unplugged the interconnect cable from the left speaker and there was a loud pop and hum from the right speaker. I hurriedly pulled the cable out of the other speaker and the noise stopped, but my mid-range speaker has not worked since then. (I am looking into getting a replacement part.)

I know that the cable leads did not touch, so nothing shorted. My questions are what caused this? Is there some sort of capacitor inside these loudspeakers? How on earth was there any power available to the speakers to cause the pop?

Yes, there are a few capacitors inside each speaker. Depending on which model 2 you have they could include up to two 27 uf's. Schematics are here.

Which 2's do you have? The original 2's have two tweeters each; the A's and B's have one each.

Is the SDA IC home brew or original? Just curious due to your "leads did not touch" comment. Also which MW is not working? The stereo or the dimensional?

Had the L-ch made the noise I'd suspect something internal with it, but because the ruckus started when you unplugged the L-ch and the R-ch made the noise, the obvious starting point is the cable.

I suggest that you check the SDA IC for continuity. The resistance measured across the two connectors at the same end of the IC (with both ends unplugged) should be off the scale high. I also suggest that you check both ends and, if you don't initially find a short, wiggle the IC around some as there may be a break in wire insulation that only showed itself when you moved the IC while disconneting the L-ch.

dbratton

Sorry that I left out some details. The speakers are SDA-2Bs. Right now, the right speaker's stereo mid is not working at all. The tweeter and the woofer are fine.

I bought these from a pawn shop and had to make my own IC. I have no reason to think that the cable has any continuity problem, but I will check it out.

I do think that whatever happened the driver is blown. So I am hoping that I can stil buy a replacement. I'm just having a spot of trouble getting through to Polk.

Thanks for all the replies.

Tour2ma

You're welcome and good luck...

In case you hadn't seen it here's a link to a downloadable SDA troubleshooting guide that may be of use.
http://www.polkaudio.com/forums/showpost.php?p=1297248&postcount=9

The thread the guide is in also has x-over schematics.