Shoot! Infinity Quantum 2 Blown Tweeters and Pots Question.

[Charivari]

clifselina, there's no parallel between a sad thing in a hobby vs. the destruction of such historically important art. Unfortunately, that dances the edge of a political subject and would be against the rules to bemoan more. :nono:

I did contact the seller about the possibility of their selling all the units together so someone could breathe life back into these, but this is what I heard back:

tell about it..i played and enjoyed for 4 hours..the better audio experience i never have..
yes this broke my heart too.
but i was thinking how to ship so heavy speakers 190lbs each...and i have to guarantee not broken on arrival..well that was terrible for me..so i decided to kil my monsters and give chance to other monsters to come alive again with original parts...so other owners can get their speakers fixed with original parts or have spares..so they not died for nothing,,they give new life to others..well i want to think that way..that make me feel better..
no they is no way to put those units back..cabinets was purchased by a friend mine him is a old proffessor of University of san diego him is a engineer..and him told me him going aput some JBL's components and make a prototype for his garage...him take the cabinets with grills today..they was mint..so nice.
so not way back

thanks..

This has raised my perspective of PowerSellers in that at least one is a person of conscience. :yes: This is just another example, though, of how the ignorance of there being enthusiasts like us has caused the destruction of one model. Nevermind the sacrilege of putting JBL components in Infinity cabinets.

rstsgsas (that's a lot of "s"s to keep writing), just curious about how you repaired the mids or rather when. When I did it with mine sometime back, I had been unable to find any information of anyone else doing it successfully. It seemed like there was the possibility that I was first and only, but I held some doubts on it.

- JP

 

[rstsgsas]

Family initials

Initials of me.wife and kids.I used a razor knife like modelers do and a magnifying glass to scrape and remove that infernal coating on the wires.Then its a matter of soldering.I had one that was broke at the edge of the dome where it meets the plastic.I dug the old wire out and soldered in a new piece from the round thru hole.It take a few tries to get it reliable.I have one in 1 of my Q3s that has been working for at least 7 or 8 months.Its tedious and patience is required.But it can be done.

 

[Charivari]

Well, that makes sense now. A lot more personal than a random word out of the dictionary like mine. Now, I wasn't asking about how to do it (I've already done it), I was more curious about a time frame as I did mine the better part of a year ago. Ah well, it is of no matter and inconsequential in the long run.

- JP

 

[rstsgsas]

About a year and a half ago.

That was when I got my first set of Quantums together.But took me several months to make it work reliably.First few tries it would come loose after playing music pretty loud.I have 1 in my quantum jrs I fixed,grill got hung on it.1 in one set of quantums and 2 spares that I have done and seem to be reliable now.1 of them I actually repaired on the inside if the voice coil about a 1/4 in from where the windings start.It is a spare although I have measured the resistance and played some music thru it,it hasn't been thru its paces yet.I have 2 more I have not done anything with yet.

 

[Kencat]

Need info on DCR of the mids

Hey there, Quantum fans,

I am just reading the last posts about the QLS destruction and gas's monster power. Boo to the former, and Yeehah to the latter. There's actually some Emits still for sale by the boob.

I'm in the middle of trying to get the two mids working in one of my Q2's. I have measured the DCR at the junction points in the crossover where the 2 sets of the white and white/black wires go to the mids. The Mids are in parallel if I understand the wiring correctly. Anyway, the DCR was 3.8 Ohms. If each mid is 8 Ohms, this then would be a close proper measurment indicating that both mids are healthy.

Can anyone confirm what the DCR is for one of these mids from an actual measure of one ???

I did manage to get the attenuating pot out for the mid, and although the steel cup is badly rusted aand looks like hell, the element looks very clean from the side holes. Also the resistance between the center lead to lead 1 and lead 2, varies from 0 to 5 Ohms as the shaft is turned, (each one in inverse to the the other). This would indicate that the pot is OK (??).

So why was there no sound from both mids :scratch2: Will accept any and all theories

Well, I'll take the pot apart and clean up what is there and will post some pics for others to see what's in there.

 

[Charivari]

I did manage to get the attenuating pot out for the mid, and although the steel cup is badly rusted aand looks like hell, the element looks very clean from the side holes. Also the resistance between the center lead to lead 1 and lead 2, varies from 0 to 5 Ohms as the shaft is turned, (each one in inverse to the the other). This would indicate that the pot is OK (??).

As I recommended before, Corrosion Block will prevent the steel housing from rusting more and will actually reduce some of it. Don't worry about it causing issues as it's electrically non-conductive -- common way to advertise the product at marine product shows is to have a TV running in a tank of it.

Your measurements are correct, just as it should be. I'd still clean it as a precautionary measure, but this does mean something else is up. I'd go through, using the crossover schematics you downloaded a little while back, and test the various components to see what's bad. It could very well be that the crossover cap has gone bad. Um, just to be sure, you did check the fuse, right? It protects both the tweeters and the midrange -- I used mine as stereo subs for a while by pulling the fuse and running just the Watkins.

- JP

 

[Kencat]

Hey JP,

I can always count on some feedback from you, appreciate it.

About the fuse - looks like it is protecting the Emits, the mids, and the mid bass, if I'm reading the schematic right. Problem is, the mid bass and Emits work ok, while the two mids don't. Can't be the fuse.

I'll check across the two big honkin resistors for proper Ohms. Without looking up how, how do you check a cap and an inductor ?

I'll get the pot back in and try it out again. Maybe the pot cleanup will have done something.

Any feeling for the mid combined DCR of 3.8 ?

 

[Charivari]

Hey JP,

I can always count on some feedback from you, appreciate it.

Well, I did say I'd help you get those Quantums going.

About the fuse - looks like it is protecting the Emits, the mids, and the mid bass, if I'm reading the schematic right. Problem is, the mid bass and Emits work ok, while the two mids don't. Can't be the fuse.

Eh, it was a long shot. Still, sometimes the obvious can be overlooked and cause those infamous "doh" moments. So, I had to ask.

I'll check across the two big honkin resistors for proper Ohms. Without looking up how, how do you check a cap and an inductor ?

Unless there's very obvious physical damage (ie evidence of hammer blows or it looks like it went through a crematorium), the inductor is most likely fine. There is equipment to measure the inductance to verify if it's still good, but a quick check with an ohm meter to verify it isn't open (no continuity) will be a good enough test for your purposes. As to the caps, there isn't a reliable means to check to see if it's good with the test gear you have on hand. So, you can either borrow the caps from the other speaker for a quick check or just straight up replace 'em. A decent 20µf Solens or Dayton and a higher quality 0.4µF bypass cap should put you back into business (if the caps were bad before) or at least serve as a good upgrade for the existing tired caps.

I'll get the pot back in and try it out again. Maybe the pot cleanup will have done something.

Any feeling for the mid combined DCR of 3.8 ?

Never did measure mine together, but that sounds about right.

- JP

 

[OMI]

FYI reference the diaphragm kits ...

RE: Infinity Quantum As tweeter diaphragms

Hello Omi, Thank you for contacting Infinity.
We do have some diaphragm kits available, however they are only supplied
to our licensed service centers.
You can find a service center in your area by visiting
www.infinitysystems.com.
Thank you and please advise if you have any further questions.

Sincerely,

Kelly

Parts Department

 

[Kencat]

FYI reference the diaphragm kits ...

RE: Infinity Quantum As tweeter diaphragms

Hello Omi, Thank you for contacting Infinity.
We do have some diaphragm kits available, however they are only supplied
to our licensed service centers.
You can find a service center in your area by visiting
www.infinitysystems.com.
Thank you and please advise if you have any further questions.

Sincerely,

Kelly

Parts Department

Thanks OMI,

Infinity was kind enough to forward my request to a distributor here in Canada who had a few diaphragms for the QLS series Emits. I picked up some and repaired the bad tweeter. Works A-ok now.

The current battle is to get the two mids singing in the one speaker. Looks like a strange issue at this point.

 

[Nat]

I had two Emit tweeters that didn't work and the problem was not the diaphragm, it was the connection to the diaphragm -- it was corroded, and so even if the two leads were together tight, no current flowed. I cleaned the connection (which requires taking the speaker apart, and there is a real possibility of pinching fingers or tearing diaphrams) and it worked fine. Its possible that when diaphragms are replaced, its simply that the new one has no corrosion that makes it work.

 

[Kencat]

I had two Emit tweeters that didn't work and the problem was not the diaphragm, it was the connection to the diaphragm -- it was corroded, and so even if the two leads were together tight, no current flowed. I cleaned the connection (which requires taking the speaker apart, and there is a real possibility of pinching fingers or tearing diaphrams) and it worked fine. Its possible that when diaphragms are replaced, its simply that the new one has no corrosion that makes it work.

Nat, I agree with what you say. The old emit that didn't produce sound, actually measured a high resistance...it was not "open" I kept the diaphragm figuring it is probably repairable working on the connections as you say.

How were the wires attached to your Emits?? Mine were soldered. The crimped on leads were soldered (with a major amount of it as well) to the diaphragm. This area on the diaphram is a large flat conductive surface.

I had a near impossible time to get the solder to take to the diaphram. I don't think the connection is good even now. It was like the surface would not heat up (too much of a heat sink?) enough.

Which Connection to the diaphram are you referring to? The soldered leads or the "buttons" at the foil ribbon? See the pics.

 

[Nat]

Its been close to twenty years since I did the repair, so my memory is hazy. But it seemed to me that the wires made a compression contact, rather than being soldered. With yours I'd resolder all the solder joints to see if that solves the problem.

 

[Kencat]

Well, I got some time to dig into the "lack of sound in the midrange drivers" problem. I was actually going to put the cleaned up pot back in, but before doing so I thought I'ld check the two resistors in the mid circuit while they were disconnected.

The 8.1 Ohm 25W er measured good. Quess what ?

The 2.7 Ohm 25W er does not measure - yup- she appears to be open. :sigh:

Good and bad news I suppose, would explain the problem, but now I have to fix it. I reconfirmed the drivers themselves and got about 4 Ohms across each set of leads at the junction where they come off of each resistor. So the drivers are still good.

I know everthing can fail, but is it likely for one of these ceramic-looking type resistors to go open???? Is it possible the multimeter leads aren't getting contact? It worked on the other one though, so I'm probably grasping at straws.

Anyone know of a good source for these resistors in the south-eastern Ontario area? Well, better crank up Google.

 

[KraftwrkTrbo]

Someone here know how the 3 EMIT tweeters are wired? 2 parellel, 1 in series? IIRC, around 3.6 ohm resistance, would lead to 5.4 ohm (to make sense).
And the 2 dome mids? Parellel?