Dead Amp returns to life

Nagrom · #1 06-05-2011, 12:42 PM

At the gig last night my amp pooched during the second set. I finished the night through the PA. At the end of the night i checked it again and it was still dead. This morning it works, seemingly fine.

4 ohm EA Whizzy 12m cab driven through a speakon cable by a Thunderfunk TFB420.

Is there a protection circuit in the speaker?(bi-metal strip)

I was running everything half open, with 40hz and below rolled off on the parametric.

Anybody know what's going on?

D.A.R.K. · #2 06-05-2011, 12:44 PM

Maybe an intermittent short in the speaker cable?

dmrogers · #3 06-05-2011, 12:52 PM

Did your head still have power?

Troubleshooting requires a process of elimination.

You have the head, the cab, the speaker cable. We can omit the guitar and instrument considering you used the same to connect to the PA.

Ideally, with a situation like this, it is best to troubleshoot right after it happens, or as soon as possible.

If everything is working properly now, I would acquire a new or known good speaker cable and wait. If it happens again AND you still have power to the head, I would try the other speaker cable. If it still doesn't work, try plugging your head into another cab. Even if you have to use a PA cab or guitar cab. You don't have to give it much power to see if it will work.

Hope this helps. Good luck!

Nagrom · #4 06-05-2011, 01:05 PM

Head is fine. No loss of AC. Had the cab die once before (last summer). Got it fixed under warrantee. Same speakon cable then, before, and now (EA factory cable)
No bad smells.

An intermittent short would than taken out an output fuse or component under load, I think.

Nagrom · #5 06-05-2011, 01:17 PM

Just fiddled with the cable, unscrewed the ends, jiggled them a bit, put it back together. Amp is now a bit hummy, used to be dead quiet. Maybe the cable has gone south?

RickenBoogie · #6 06-05-2011, 02:26 PM

Use a new cable, and you'll have the answer.

Nagrom · #7 06-05-2011, 02:28 PM

Got a new cable. No change.

southpawpa · #8 06-05-2011, 04:19 PM

Speaker jack then perhaps?

T-Bird · #9 06-05-2011, 10:40 PM

Hi.

Quote:

Originally Posted by southpawpa

Speaker jack then perhaps?

^This. Or the solder joints most likely.

For numerous reasons, soldering a relatively thick leg of the jack is nearly impossible it seems. After a faulty cable, the jack solder joints is the most likely culprit.

The non PCB types are marginally better, some of the PCB ones, horrible. Especially if the PCB has the cross-over inductors on it as well.

Regards
Sam

Munjibunga · #10 06-05-2011, 10:47 PM

That happened to me at my first gig with my Heart-Rock. Turns out, I pushed both the mute button and the A/B button when we went on break. When we came back, I pushed the mute button to unmute it but, since I was plugged into A and had B selected, no sound. I whipped out my Walter Woods spare, played the gig, and realized what had happened as we were tearing down.

Nagrom · #11 06-05-2011, 10:53 PM

I played the gig this afternoon with the new cable and all seems fine. Go figure.

T-Bird · #12 06-06-2011, 12:10 AM

Hi.

Quote:

Originally Posted by Nagrom

I played the gig this afternoon with the new cable and all seems fine. Go figure.

Cold/cracked solder joints do behave just like that.

In order to avoid nasty surprises in the future, I'd check the soldered connections in any case.

I've never seen or heard a Speakon jack going bad all by itself, but that doesn't mean it's not possible. Especially with the numerous imitations to the Neutrik ones there is on the market.

Regards
Sam