I need help figuring out what is up with my bass cab

[JimChjones]

The SWR 'crossover' circuits I've found on line are pretty trivial.It should be reasonably straightforward to follow the wires and confirm the circuit diagram, then use an ohm meter to work out where the break in the circuit is. The circuits I found aren't even true crossovers, simply an in line capacitor to protect the tweeter and an Lpad.

 

[Matthijs]

The fuse only protects the horn, and the horn works.

It probably is, but I follow this rule when trouble shooting: always check a fuse when you find one. It saved me a lot of work over time. You never know, and it's a lot easier than resoldering the board.

 

[GreyBeard]

Try run the amp directly to the speakers bypassing the jack and internal wiring.

This is the best way to check it out. Take an old speaker cable that works and cut off one end and strip the wires so you have about an inch of bare wire hot and cold. Twist the bare ends onto the terminals of the speakers one at a time and plug the other end into your amp with the volume down and play around with it. This will let you know if the speakers are fried or it is just the xover network.

 

[Rabidhamster]

So I recently bought a used SWR Big Bertha 2x15. Long story short I plugged in a 300 watt 4ohm head to test it, and only got noise from the horn.

Opened it up, 9 volt tested both 15" speakers, both are functioning.

The wiring all seems intact and tight, what else can go wrong?

It's between the amp and the tweeter. You know the amp works and the drivers all work. So that means cross over or wiring. Could be any number of things, if it isn't the driver, and if it can't be the fuse, that leaves the cross over capacitors or the wiring from the cross over to the woofers.

You can test the crossover with alligator clip leads to jumper around it to bypass straight to the woofers - if that works it's something in the crossover, probably a bad cap or a corroded switch/knob if applicable

 

[bumperbass]

The SWR 'crossover' circuits I've found on line are pretty trivial.It should be reasonably straightforward to follow the wires and confirm the circuit diagram, then use an ohm meter to work out where the break in the circuit is. The circuits I found aren't even true crossovers, simply an in line capacitor to protect the tweeter and an Lpad.

This cab has a 2-way xover @ 5kHz.

 

[bumperbass]

It's between the amp and the tweeter. So that means cross over or wiring. Could be any number of things, if it isn't the driver, and if it can't be the fuse, that leaves the cross over capacitors or the wiring from the cross over to the woofers.

You can test the crossover with alligator clip leads to jumper around it to bypass straight to the woofers - if that works it's something in the crossover, probably a bad cap or a corroded switch/knob if applicable

Probably not a cap, unless it's shorted. More likely a coil connection in the xover.
Even if it was a shorted cap, the OP wouldn't get anything out of the horn.

 

[Rabidhamster]

Probably not a cap, unless it's shorted. More likely a coil connection in the xover.

Nah caps fail this way all the time, but I do agree with SWR it's always more likely a loose or corroded spade connector.

 

[BassmanPaul]

The 'fuse' is actually a ballast lamp that protects the diaphragm of the tweeter. It has nothing, or should have nothing to do with the woofers. With a used cab anything could have been done to it so you will have to trace out the wiring.

 

[agedhorse]

Nah caps fail this way all the time, but I do agree with SWR it's always more likely a loose or corroded spade connector.

Cap failures aren't very common, and shorted caps are even more uncommon. If it was failing short circuit, almost certainly there will be evidence of heat, and it would likely either put the amp into protect of damage the amp.

The fault is most likely an open connection somewhere on the crossover board in series with the woofer signal path.

By any chance does this crossover version have biamp capabilities?

 

[LowActionHero]

That looks worthy of a resolder

 

[Slevage]

Nah caps fail this way all the time, but I do agree with SWR it's always more likely a loose or corroded spade connector.

Modern capacitor failure is rare except when they are used in an AC motor starting device.
People often replace capacitors that are in perfect working condition.

 

[agedhorse]

Modern capacitor failure is rare except when they are used in an AC motor starting device.
People often replace capacitors that are in perfect working condition.

People also ruin a lot of gear replacing perfectly good caps.

 

[Pulverizor]

Any luck @Chris Toy?

 

[JRA]

I'd bypass the crossover first and connect the amp directly to the speakers. That way you'd be sure the problem is in the xover.

Easy fix is remove dam thing wire jack directly to the speakers.

 

[Clark Dark]

OP ,
did you figure out that seemingly burned spot under the nut and bolt? That could mean burned trace on the circuit board. Take another pic with the board turned over.