ADS 1290 No Midrange Output

[ClearChannel]

I recently obtained a pair of used ADS L1290.

I am not getting any output in one of the midrange units. I pulled midrange unit out and tested with low level speaker output & it does produce sound. Any idea what to trouble =shoot? How do you remove crossover, mine appears to be impossible to remove from cabinet?

The speakers are scuffed up, so I would like to refinish them. All other drivers in work fine.

 

[Porkloin]

Are there fuses on the back? Does it put out anything if you hook the tweeter wires up to it? Photos?

 

[ClearChannel]

Are there fuses on the back? Does it put out anything if you hook the tweeter wires up to it? Photos?

Yes, I pulled out both fuses &they check ok. The tweeter works. The midrange does not work. But when I disconnected the midrange it did work. So not getting any signal to the midrange leads. All other speaker components work.

 

[GD70]

Yes, I pulled out both fuses &they check ok. The tweeter works. The midrange does not work. But when I disconnected the midrange it did work. So not getting any signal to the midrange leads. All other speaker components work.

Sounds like something is up with the crossovers, but did you swap the drivers and see if the issue follows the tweeter in question? That will tell you, driver, or crossover.

 

[ClearChannel]

Sounds like something is up with the crossovers, but did you swap the drivers and see if the issue follows the tweeter in question? That will tell you, driver, or crossover.

The tweeter is fine. It is the midrange that I do not get any audio from. I think it is the crossover. No audio to the midrange leads. The back panel where the crossover is mounted to is impossible to get loose, even after removing the allen screws.

 

[GD70]

The tweeter is fine. It is the midrange that I do not get any audio from. I think it is the crossover. No audio to the midrange leads. The back panel where the crossover is mounted to is impossible to get loose, even after removing the allen screws.

Ah, I meant the mid. Was sick all week, still a bit foggy!

 

[mike0565]

Try a putty knife and gently tap with a hammer.

 

[slimecity]

So just to confirm - you also tried connecting a random speaker to the midrange wires to confirm there is no audio signal there at all?

 

[Porkloin]

I had to put an "L" hook in mine and do a "tapping fulcrum" thing with a wrecking bar (bad choice of words) on a rubber screw driver handle. The drivers were even worse. If you get them out, you may want to resist the temptation of using some sticky liquid to put them back in.

 

[embrown057]

The safest way to remove the crossover is to remove the lower woofer then push it out. The plastic can become very brittle from age, you'll be hard pressed to find another crossover. If your confidant your drivers are working correctly you'll find the stock crossover is very simple to work on. They used very cheap lytics'. not surprising to find one open after all the years of use. I would suggest you consider sending the drivers to Richard for restoration, well worth the investment. The inductors are low quality but adequate, if you have a bad inductor you'll know just by visual inspection. If coil is not burnt there fine, measure them for conformation. Also carefully clean and test the bi-amp switch, that can cause a dropped midrange signal to the drivers. Being you have booth mid drivers out I'm still inclined to strongly consider they are defective. The fluid is more than likely dried and has caused the failure. They still can measure fairly close and produce some sound and still not perform correctly having no or low fluid. This also damages the voice coils integrity, fraying off the bobbin and chaffing.

 

[Porkloin]

The safest way to remove the crossover is to remove the lower woofer then push it out. The plastic can become very brittle from age, you'll be hard pressed to find another crossover. If your confidant your drivers are working correctly you'll find the stock crossover is very simple to work on. They used very cheap lytics'. not surprising to find one open after all the years of use. I would suggest you consider sending the drivers to Richard for restoration, well worth the investment. The inductors are low quality but adequate, if you have a bad inductor you'll know just by visual inspection. If coil is not burnt there fine, measure them for conformation. Also carefully clean and test the bi-amp switch, that can cause a dropped midrange signal to the drivers. Being you have booth mid drivers out I'm still inclined to strongly consider they are defective. The fluid is more than likely dried and has caused the failure. They still can measure fairly close and produce some sound and still not perform correctly having no or low fluid. This also damages the voice coils integrity, fraying off the bobbin and chaffing.

I had electrolytics in the band-pass leg of my 780 /2's, but did they use those in the 1290's as well? Except for the high uF woofer caps, I thought ADS used film caps for the most part. I've never seen photos to the contrary, except for my own.

 

[ClearChannel]

So just to confirm - you also tried connecting a random speaker to the midrange wires to confirm there is no audio signal there at all?

So just to confirm - you also tried connecting a random speaker to the midrange wires to confirm there is no audio signal there at all?

Yes, I tried substituting another unrelated driver (Advent Tweeter) that was working. When I connected it to the midrange leads, I did not get any audio out of it.

 

[ClearChannel]

The safest way to remove the crossover is to remove the lower woofer then push it out. The plastic can become very brittle from age, you'll be hard pressed to find another crossover. If your confidant your drivers are working correctly you'll find the stock crossover is very simple to work on. They used very cheap lytics'. not surprising to find one open after all the years of use. I would suggest you consider sending the drivers to Richard for restoration, well worth the investment. The inductors are low quality but adequate, if you have a bad inductor you'll know just by visual inspection. If coil is not burnt there fine, measure them for conformation. Also carefully clean and test the bi-amp switch, that can cause a dropped midrange signal to the drivers. Being you have booth mid drivers out I'm still inclined to strongly consider they are defective. The fluid is more than likely dried and has caused the failure. They still can measure fairly close and produce some sound and still not perform correctly having no or low fluid. This also damages the voice coils integrity, fraying off the bobbin and chaffing.

Thanks for the advice! I will attempt to remove the lower woofer to get at the crossover. Again, I suspect it may be in the crossover or the leads that go to the midrange, as all other drivers work. The other speaker works fine
. Cabinets are rough, so they probably had a hard life.

 

[ClearChannel]

The safest way to remove the crossover is to remove the lower woofer then push it out. The plastic can become very brittle from age, you'll be hard pressed to find another crossover. If your confidant your drivers are working correctly you'll find the stock crossover is very simple to work on. They used very cheap lytics'. not surprising to find one open after all the years of use. I would suggest you consider sending the drivers to Richard for restoration, well worth the investment. The inductors are low quality but adequate, if you have a bad inductor you'll know just by visual inspection. If coil is not burnt there fine, measure them for conformation. Also carefully clean and test the bi-amp switch, that can cause a dropped midrange signal to the drivers. Being you have booth mid drivers out I'm still inclined to strongly consider they are defective. The fluid is more than likely dried and has caused the failure. They still can measure fairly close and produce some sound and still not perform correctly having no or low fluid. This also damages the voice coils integrity, fraying off the bobbin and chaffing.

Only One midrange not working. The other speaker is fine....all drivers on it work. I have not cleaned the bi-amp switch, as both woofers & tweeter work.

 

[Drugolf]

My guess is that it is a lead/wire issue. Remove the woofer and move the wires around with signal and see if it comes to life? A broken/disconnected wire somewhere.

 

[toxcrusadr]

Or a bad trace or solder joint on the board itself. If you have a meter, trace for continuity backwards from the ends of the midrange leads. Of course when you get to the cap it will not pass DC so you'll have to skip that. But the cap itself should show a low DC resistance initially and climb up to near infinity in a few seconds. If it starts at infinity (open) it's probably the cap.

 

[ClearChannel]

I was able to remove the crossover. It appears has never been removed. I suspect the problem is in the crossover, but I am stumped right now. Again the midrange driver does work, BUT will pass audio if connected directly to speaker leads (the midrange leads are red & white), the leads from the midrange going to the crossover also work.

Upon removing the crossover, the wires are as follows from top to bottom:

Yellow > T1 Labeled on Circuit Board
Brown > M+
Red > T+
White > M-
Black > W-
Black > W-
Blue > W+
Blue > W+

I later realized that if the red & white leads correspond to the midrange, why was red lead on the T+ terminal & white lead on the M- terminal?
So I tried wiring the midrange as follows ( red lead to M+ & white lead to M-) and did not get any audio from midrange unit. I tried wiring the midrange to the tweeter terminals (red lead to T+ & white lead to T-), again no audio.

See attached photos of crossover. WHEN I REMOVED THE TWEETER IT SAID IT HAD BEEN REMANUFACTURED. Could a midrange driver pass audio from raw speaker leads but not from crossover output?

As I indicated earlier, when there was no output in the midrange, I removed it and substituted a working Advent tweeter....no audio came out of it either. So it appears there is no audio coming out of the T+ & M- terminals, this is where the midrange is connected. The tweeter is connected to Brown M+ & Yellow T- terminals.

Any advise on where to go next?

 

[slick.one]

I had the same kind of problem with a pair of Vandersteen 2Cis and the resistors in the midrange section of the circuit board were fried. Replaced them and the midrange works fine now.

 

[sax6]

Did you cleaned or gently ( gently ) with a steel wool '' sanded '' the fuse holder ?
Happened to me once on a pair of Polk.

 

[GlennW]

Problem seems to be crossover. My recommendations for troubleshooting:
Disassemble the crossover circuit board from its plastic case. To do this, you have to remove the 4 screws holding the board to the case, the single nut holding the large inductor, and the terminals; the nuts for the terminals are visible from the side of the case. They are a tough reach.
After separating the board from the holder, start testing parts. I have attached a schematic. The likely suspects are fuse F1, resistor R2 and capacitor C2.
Good luck.

Glenn