Marshall cabinet dead? Advice requested

[rashayritto]

Hey guys I've been scratching my head and checking around the interwebs for some adequate documentation on cabinets going dead. I have a Marshall MC412A 4x12 cabinet that has ceased to provide any output. Measuring the resistance from either jack yields no reading (multimeter remains at 1). I removed the back and and found that a couple of the slide on contacts seemed a bit loose so I pressed those onto their tabs until they were properly in place. Still no change. I can only conclude that the stereo/mono switching circuit is at fault so I'm planning to hardwire the whole cabinet with 12 gauge and use a single jack. Is there anything else I should try trouble shooting before going forward with this? Any insight is much appreciated.

The cabinet has seen extremely light use (maybe a few hours at most) for as long as I've owned it and has only been moved around very little. I find this situation pretty disappointing and hope I just overlooked something stupid

 

[MetalManiac]

Re: Marshall cabinet dead? Advice requested

Yes, take an impedance reading off each speaker first alone by itself. If one of them blew , it'll prevent the cabinet from making any sound. Thats my guess, is that a speaker is blown, and it'll still be dead if you wire it to a mono jack. Check the terminals on the old jacks first.

 

[rashayritto]

Re: Marshall cabinet dead? Advice requested

just checked each speaker individually and unless both my meters are broken, EVERY speaker is dead?

 

[MetalManiac]

Re: Marshall cabinet dead? Advice requested

You have to disconnect them and then test each of them seperately. One is dead, thats for sure. I'm not an expert, I could be wrong, but I have , like 8 Marshall cabinets. ( Plus I want a set of Zephyrs, lol)

 

[rashayritto]

Re: Marshall cabinet dead? Advice requested

I removed all the connecting wires so that every speaker was isolated if thats what you mean. I did have a Laney AOR die on me (still havent determined if a screen resistor or tranny problem) while connected to this cab, so I wonder if it took the speakers out with it. Time to order some eminence speakers I guess

 

[MetalManiac]

Re: Marshall cabinet dead? Advice requested

I dunno man. Check your meter on a known good speaker I guess.

 

[Little Pigbacon]

Re: Marshall cabinet dead? Advice requested

You can also check to see if the voicecoils are welded in place; that often yields a coil that looks a lot like a short to a DC ohm-meter. You push in very gently on the cone to see if it moves. If the motor doesn't move, the driver is dead.

 

[MrTondo]

Re: Marshall cabinet dead? Advice requested

Go with the advice of litte pigbacon here.

Yet it is very concievable that you blew the speakers if something in the tranny blew. Did you hear anything at that time? Any particular noise when it died?

 

[Funkfingers]

Re: Marshall cabinet dead? Advice requested

There is always the battery 'n' two probes test. If this produces an audible blip and physical movement of the cone, the 'speaker lives.

 

[rashayritto]

Re: Marshall cabinet dead? Advice requested

Go with the advice of litte pigbacon here.

Yet it is very concievable that you blew the speakers if something in the tranny blew. Did you hear anything at that time? Any particular noise when it died?

I don't remember hearing any pops or hiss. Just the amp slowly fading out. I can't recall if I ran any other heads through it since then. On the bright side of all of this I have an excuse to change out these cheap Celestion's with some Swamp Thangs. I'll just have to wait til I start my big boy job next month and have that sort of disposable cash.

As for the battery test, I'll grab a 9 volt today and see if any of the speakers have some juice left