Fender Rumble 115 cabinet not working all the sudden

[dano2]

hi all, per the title, my Rumble 115 stopped working. Fear that the input on the back burned out or something. I took a look
but saw nothing, everything is all connected, no loose wires. I noticed that there is a small circuit board. I called fender but
because its not on warranty any longer they cant really help. But said there should be a part number if you pull out the circuit
board, no screws unable to pull out circuit board. Got a couple number off of it but nothing showing up in google. Running
out of ideas unless i want to take it to an electronics place, ugh... im a pretty good DIY person so if I could find the thing
I could just splice on a whole new input on the back... any thoughts or ideas" greattly appreciated.

 

[JimChjones]

You need to start with diagnosing the problem. Too many people order parts they don't need because they don't actually know what the problem is. If you've got a mate who's got some familiarity with basic electronics and loudspeakers then it would be well worth seeking their assistance.

The first question is whether its completely stopped working or whether you are getting any sound out of the horn. The next question is whether you have tried it with another amplifier, and have you tried both speaker connections. Surprisingly even plugging it in to a headphone socket on something convenient, even a mobile phone, is enough for that test.
If you've got sound with another device then clearly its not the cab at all. If you've got sound from the horn but not the main speaker it could be crossover or a bad connection somewhere, which could be a faulty socket, espeiclly if one works but not the other.
Probably best to go this far then report back.

Assuming its a 115 cabinet, not a combo, the small circuit board is going to be a crossover. The next step would be to take the panel out of the back and connnect an amp up to just the 15in speaker. Don't try connecting anything up to the horn: its easily damaged. If you don't get sound direct to the speaker, eliminating crossover and sockets, then you have a very sick bunny. Others can tell you whether the crossover/plugs assembly is available as a spare.

 

[kevrex]

the last two "my pickup is dead" problems i fixed were simply dirty connections. maybe clean the input jack and see if that helps.

 

[agedhorse]

Why would you think it's the circuit board? That's just a wild guess, and the PCB assembly isn't available as a repair part anyway.

If you can't do proper troubleshooting, take it to somebody who can. It will be cheaper than replacing the wrong part anyway.

 

[agedhorse]

the last two "my pickup is dead" problems i fixed were simply dirty connections. maybe clean the input jack and see if that helps.

Not going to be a dirty speaker jack, the signal is too big and the impedance too low for that to be an issue.

 

[Wasnex]

Could be the speaker cable. Try a different speaker cable.
Could be the amp. Try a different amp.

...or try another speaker with the existing amp and speaker cable.

 

[Nebadon2000]

What Wasnex said

Are you using Speakon: if so is it genuine Neutrik

 

[toughluck]

Whip out a multimeter and check if you have the expected resistance across the woofer (disconnected from the crossover and connected to it).
If it's normal, then don't touch the electronics.
Check your amp-speaker cable with the multimeter if resistance tip to tip and sleeve to sleeve is minimal. Then check if tip to sleeve is isolated.
If you verified all that, check if you have continuity from tip and sleeve to crossover output hot and cold.

 

[toughluck]

Not going to be a dirty speaker jack, the signal is too big and the impedance too low for that to be an issue.

Unless there's tons of dirt in it and the jack is not pushed fully inside.

 

[agedhorse]

Red

Unless there's tons of dirt in it and the jack is not pushed fully inside.

Ridiculously unlikely.

 

[KevInDaBassment]

Whip out a multimeter and check if you have the expected resistance across the woofer (disconnected from the crossover and connected to it).
If it's normal, then don't touch the electronics.
Check your amp-speaker cable with the multimeter if resistance tip to tip and sleeve to sleeve is minimal. Then check if tip to sleeve is isolated.
If you verified all that, check if you have continuity from tip and sleeve to crossover output hot and cold.

This ^

A decent multimeter isn't too expensive and can be useful for many different things around the house. Read the manual on what to set it to, then check for proper impedance (should be 8 ohms). I'd grab a fresh speaker cable and use that to touch with the multimeter probes.

It's also a good idea to try and reduce variables...
- Tried it with a different speaker cable?
- Used the other cab input (SpeakOn or 1/4" jack)?
- Swapped in a known-working amp besides your own?
- Connected your amp to a different known-working cab?
- Tried a different bass and instrument cable (going straight into the amp)?

Those are all things you can do/test with minimal/no electronics experience. Within reason, those tests shouldn't damage the cabinet much further than it already is. At least then you can narrow it down for a buddy or repair shop. If it does turn out to be the cabinet, depending on the severity of the damage, it may be better to start looking for a replacement cabinet

 

[agedhorse]

This ^

A decent multimeter isn't too expensive and can be useful for many different things around the house. Read the manual on what to set it to, then check for proper impedance (should be 8 ohms). I'd grab a fresh speaker cable and use that to touch with the multimeter probes.

It's also a good idea to try and reduce variables...
- Tried it with a different speaker cable?
- Used the other cab input (SpeakOn or 1/4" jack)?
- Swapped in a known-working amp besides your own?
- Connected your amp to a different known-working cab?
- Tried a different bass and instrument cable (going straight into the amp)?

Those are all things you can do/test with minimal/no electronics experience. Within reason, those tests shouldn't damage the cabinet much further than it already is. At least then you can narrow it down for a buddy or repair shop. If it does turn out to be the cabinet, depending on the severity of the damage, it may be better to start looking for a replacement cabinet

Except that you shouldn't measure 8 ohms with a multimeter, that's the nominal impedance. The measurement will be DC resistance and will be roughly 60-80% of the nominal impedance.

 

[KevInDaBassment]

Except that you shouldn't measure 8 ohms with a multimeter, that's the nominal impedance. The measurement will be DC resistance and will be roughly 60-80% of the nominal impedance.

@OP, I'll happily take correction from this gent, take what he says to heart ^

 

[toughluck]

Ridiculously unlikely.

I know. But one of those days we're going to hear hoofbeats and the one who yells "zebras!" will be right!

 

[Bent77]

Is that like a prophecy? The chosen one is named agedzebra?

 

[staccatogrowl]

No, that would be fountain-of-youth unicorn

 

[agedhorse]

No, that would be fountain-of-youth unicorn

I wish!

 

[Tim Skaggs]

my Rumble 115 stopped working.

Was it working the last time you used it and not working the next set, day or week, or did it stop working in the middle of a song / bass solo?

The point here is where to begin trouble shooting. If the cabinet worked one day at a location and didn’t work the following day somewhere else, you need to duplicate the working config, same bass, amp, speaker cable, etc.

If it quit working mid-song, or mid-note, something failed, but it could still be bass, cable to amp, amp, cable from amp to speaker cab, and speaker cab.

Since you started with this hypothesis;

Fear that the input on the back burned out or something.

My guess is you were playing very loud & then everything went silent?
Best I can tell from reading and looking at schematics, the 15” speaker is not connected to the low side of a crossover, only the tweeter is protected from low frequencies. The 15” is getting full range signal. In other words, it appears there is no crossover network to “burn out” for the 15” speaker.
Was there any indication to make you suspect something burned? (Like an odor?). There doesn’t have to be a crossover present for something to burn. Other things can burn…

 

[dano2]

Hi. No, I was playing it inside the house, low volume, no indications of anything, no smell of a burnout. Just stopped. The head is fine, tried it on another cabinet.
I read not to use an instrument cable, only speaker cable or you could blow something. Well I used by accident an instrument cable and didn't realize, so i switched back quickly to the speaker cable. ...

 

[Wasnex]

Hi. No, I was playing it inside the house, low volume, no indications of anything, no smell of a burnout. Just stopped. The head is fine, tried it on another cabinet.
I read not to use an instrument cable, only speaker cable or you could blow something. Well I used by accident an instrument cable and didn't realize, so i switched back quickly to the speaker cable. ...

An instrument cable is not able to handle the current that occurs pushing a speaker. The risk is the instrument cable will break down or possibly short. This could cause damage to the amp, but I can't think of any way it would damage the speaker.