Dimensional driver issues - SDA 2BTL

audiocr381ve

Tonight I tipped my left speaker forward to put pads under my spikes and heard something...something very good. All of a sudden the left speaker sounded fuller. I put the speaker back into to position and it sounded thinner. I tipped it forward again and the same thing happened. I put my hands to both the stereo and dimensional driver and the stereo driver was obviously vibrating a lot more than the dimensional driver with music being played. So I tipped the speaker forward and touched the dimensional driver and now it was vibrating about equal with the stereo driver.

So, I pulled the dimensional driver and there was a solid connection. Next, I take out the PR to inspect the binding post and crossover. The binding post was all good. I then wiggled the inputs on the crossover and discovered my problem there. The dimensional was coming in and out as I wiggled the cables. So I pulled the crossover out and couldn't find out how this was occurring. Everything looked good. I'm kind of stumped. What could I be missing? Could it be the mate-n-lock connectors becoming loose?

audiocr381ve

Played some music again. Wiggling the cables isn't do it, it's pushing the entire mate-n-lock upwards that does it. Has anybody else had this problem? How could I fix this?

audiocr381ve

Wow, now I'm really at a loss now. Although I didn't want to, I had extra male and female mate-n-lock connectors from Mouser from my CRS+ project. SO, I replaced both the male 3 pin from the binding post to the female 3 pin on the crossover input.

This did NOT fix my problem. The dimensional driver in the left speaker is STILL out. However, the right speakers dimensional driver is working perfectly.

Where else on the crossover could there be an issue? What's next to check?

Thanks for the trouble shooting help in advanced and sorry about the frustration.

quadzilla

Flip the crossover over and see if it looks like the solder pad has lifted or a trace is broken. If it works when you push up only, then pushing up is causing something to make contact, and it could be a bad trace.

drumminman

Quad has a good tip. Since you replaced the connectors already that should rule them out as the source of the problem. It has to be the board or the driver or the wiring between the board and the driver.

After the board I would pull the wiring to that driver and inspect if for nicks, cuts, etc.

If wiring is OK, then I would check the MW. Could be with pulling it out for mods, handling or even just age some of the wire connections from the voice coil to the connection tabs are hanging by a thread/making intermittant contact. These speakers are 20+ years old. Try switching the dimensional drivers from the good cabinet and see if that helps. If it does get a replacement from Polk.

Good luck!

Joe08867

Have you tried pressing on the cone of the driver? I had one that had a disconnect between the basket and the cone.

It may just be a bad driver.

audiocr381ve

Well, it's not the driver. I swapped in the working dimensional driver and it still didn't work in the left speaker.

I don't understand how the crossover could just crap out like that. Could a trace really go bad? Good thing I have another set and a pair of Tony's boards on the way.

Is there anything else I could check before I have to take all the parts off that board and swap in a different one?

audiocr381ve

Just to confirm, I pulled the crossover in the left speaker again. It does in fact work when I push the female 3 pin mate-n-lock on the crossover input towards the sda IC side. This is a recent issue as well, I've always checked both drivers to ensure they're moving. I don't understand how this could have happened.

drumminman

You ruled out a bad driver.

It must be either the board or the wiring (unlikely). You could try getting rid of the molex connectors and soldering the wires directly to the board - a bit of a pita.

Or wait until Gimpod's boards arrive. Intermittant problems like this a **** to track down and repair.

I once had Shure SME 3009 MkII tonearm that I bought new that had an intermittant short. It sounded fine during some sessions, and during others terrible. I took it back to the retail store I bought it from and they couldn't find the problem. At my insistence they sent it to the factory - twice! First time the factory said there was nothing wrong. Second time, they finally diagnosed and fixed it. Worked great after that - at least until I got divorced from it!

The store owner was a bit pissed at me, as though I was making up the problem.

audiocr381ve

drumminman wrote: »

You ruled out a bad driver.

It must be either the board or the wiring (unlikely). You could try getting rid of the molex connectors and soldering the wires directly to the board - a bit of a pita.

Or wait until Gimpod's boards arrive. Intermittant problems like this a **** to track down and repair.

I once had Shure SME 3009 MkII tonearm that I bought new that had an intermittant short. It sounded fine during some sessions, and during others terrible. I took it back to the retail store I bought it from and they couldn't find the problem. At my insistence they sent it to the factory - twice! First time the said there was nothing wrong. Second time, they finally diagnosed and fixed it.

The store owner was a bit pissed at me, as though I was making up the problem.

Yea, this whole thing is a PITA. Spent several hours troubleshooting last night.

Well, I get what you're thinking. But I literally soldered new connectors to the board last night. Fresh connections. Is there anything else that could have happened at the crossover that I should be looking at?

drumminman

One thing you might try in order to confirm it's the board is stick a continuity tester at the point at which the connector contacts the board with the other end on the quick disconnect (disconnected from the driver). Get continuity and then wiggle the connector at the board end to see if you can make the problem happen. Move the probe around the MW ouputs of the board and test at different spots, testing each end of the wires going to the dimensional drivers while wiggling the connector.

Don't know how well this'll work, but I'd try it. May help to narrow the problem down.

SDA1C

Look ALL over the board for bad joints. It could be that pushing on the plug is flexing things enough to making contact on a cold solder joint on the other side of the board.

Phasewolf

You may have a micro crack in one of the traces I have seen this with TV sets quite a few times. Wait for new boards that will tell you for sure. Are you using the stock boards as of now?

audiocr381ve

Thanks guys.

Yes I'm using stock boards right now. I have boards from my unfinished CRS+ project that I'm going to swap in, although they have different components on them right now.

How would one repair a trace? I'm almost positive it's a trace now. I think to safe to say that it's the SDA IC trace to, because the stereo driver is functioning perfectly, right?

Phasewolf

You would need too look at the trace and run a wire from one end of the trace too the other point too where that trace connects. If you want you can just do that too all the ones for that connector and that should fix it if its the issue. Plus it is easy too undo.

audiocr381ve

SDA1C wrote: »

Look ALL over the board for bad joints. It could be that pushing on the plug is flexing things enough to making contact on a cold solder joint on the other side of the board.

PROBLEM SOLVED!

Well, I just recently swapped these boards in from my CRS+'s. I intended to use them in that project but got curious as to how the new Clarity Caps sounded in the 2BTL's. So, I've not been living with this problem for more than a few weeks.

Anyway, SDA1C was on the money. I found 1 cold solder joint going to one of the small inductor legs. It was cracked, so every time I wiggled, it made contact. Well, broke out the soldering iron and fixed that, and VIOLA! Back to perfect working order! Thanks for all the help guys.

Toolfan66

I thought it might be the speaker rings...

gdb

Who is Viola......is she hot ??

SDA1C

She's from Wisconsin...:cheesygrin: Glad we could help man. Rock on!

audiocr381ve

Toolfan66 wrote: »

I thought it might be the speaker rings...

I took those out, they sounded terrible! :P

drumminman

Congrats!

audiocr381ve

drumminman wrote: »

Congrats!

Thanks!

headrott

audiocr381ve wrote: »

I took those out, they sounded terrible! :P

????????????????

Greg

inspiredsports

I just noticed this thread.

Cold solder joints are very common on modified boards when you are first learning to solder.

Someone mentioned trace cracks as found on cheap mass-produced TV sets. Trace cracks on vintage Polk boards are almost unheard of as the boards they used are very heavy.

evhudsons

Ha ha, great memories!

I'm glad you guys kissed and made up.

audiocr381ve wrote: »

I took those out, they sounded terrible! :P

audiocr381ve

evhudsons wrote: »

Ha ha, great memories!

I'm glad you guys kissed and made up.

I think Larry might still have a problem with me so I may need to send him a 6 pack of some local brew, a Stone IPA perhaps.

evhudsons

stone of tone ipa, or maybe some oliver bubbly?

For the record I think his rings are awesome, and it very much helped tighten up the bass and mids even more so than spiking. It may be that my CRS+ is more sensitive.

I love IPA, and about to make a batch.