ADS L780/2 Mid not working. Please help.

[Corbin Gross]

Hey, guys. I have a pair of ADS L780/2 speakers with a problem. The speakers are in great shape, but one of them has a mid not working.

I tested the mid, and it's still working. It sounds fine when I hook it up directly to a receiver. But when I connect it to the crossover it's not making any music.

So obviously, the problem is with the crossover somewhere, but I'm not sure how to test that. Do you guys have any suggestions about diagnosing a crossover? Is there a common problem to check for?

Thanks in advance for any help, guys.

 

[dogwan]

Does this model have fuses under a cover on the back?

If I'm not mistaken the L780 had a dedicated fuse for the mids, while the /2 version did away with the mid fuse. But, it may have happened somewhere during the production run. Regardless check the fuses 1st off.

The next step would be to swap crossover from the good speaker to the bad. If the mid comes on then you know it really is the crossover and not the wiring or the driver.

The crossovers are pretty bulletproof on ADS speakers. Look for corrosion on the traces or loose connections of the push-on connectors for the wiring. If nothing is obvious I would start tracing the crossover with a mutli-meter. The inductors will show continuity if good. IF a cap has gone bad it is most likely the electrolytic one, but the film (gray box) caps could conceivably go bad just not as likely. Finally check the resistors. It might help to have both crossovers out and compare measurements.

Hope that helps.

 

[Corbin Gross]

Thanks for the advice.

I tested the wiring from the crossover to the driver separately. It's still good.

I'll try testing the individual crossover components and see if I can figure it out that way.

Does anybody have a schematic for the crossover?

 

[Corbin Gross]

Oh, and I forgot to answer about the fuse. No fuse on this one. I wish...

 

[Corbin Gross]

Hey guys. Just wanted to see if anybody had suggestions on how to test the individual channels or whatchamacallit on a crossover?

I'd like to narrow down what part of the board is giving me trouble. I don't have access to the other crossover right now. It'd be great to be able to swap the components to see if that points to any problems. I'll try to get to the other speaker and give that a shot.

I think for now I'll just go through and resolder the joints and see if that'll help. My first guess would be a cold joint since the wires and connections seem to be fine.

I appreciate ay help, guys.

Thanks!

 

[Corbin Gross]

Hey, Guys.

So I'm working my way through this x-over, but I'm not sure if I'm figuring anything out.

There're two 11uf caps, two inductors and a resistor on the circuit for the mid. 1 cap and one inductor on the way to the mid and 1 cap, one inductor and 1 resistor on the short cut back to the ground.

I don't understand how x-overs work, but I think I figured out what's hooked to what at least.

I checked both caps and they're fine. I resoldered all the joints. I just can't figure this thing out. I'm sure it's just got to be a broken connection somewhere, but I'm just not sure how to check the points of the circuit through...