PA Speaker power cutting out - help

dilithium85

Gigged the other night and just before we started one speak was cutting out and back on with a loud pop even when no sound was going through it.
Tried different plugs, kettle leads, mics but problems persisted. The other speaker was fine
I'm guess is the connection inside the speaker that is loose? 
It's an ld systems ldpn152a2 active speaker
(luckily we had a back up speaker) 

Danny1969

Probably not a loose wire as solid state amps (AB or class D) generally wouldn't power off with no load ... possible short circuit as in wire has chaffed against chassis possibly but unfortunately probably more likely an abnormal load fault such as bad cap. 
Take it apart and have a good look at all connections ... especially wires that pass through holes in a grounded chassis. 
Then look for bad joints  .... normally the joints of things that get hot like large resistors. Bad caps will often have a bulging top rather than a flat top ... not always but it can be a very obvious sign. 

dilithium85

I'll post pictures later hopefully will someone can see a fault. I'm alright with guitar wiring but not pa

dilithium85

Opened up. Works fine when lying down as soon as I put it up right it pops loudly and power cuts out intermittently.
Only happens when a signal is put through it. The circuit and solder looks fine all inputs work but do the same pop when upright. 
Tried different cables. Line out works when going to another speaker and I disconnect the problem speaker. Help

dilithium85

Module is fine when taken out of the case if its lying down, when wiggling cables it's fine as well

dilithium85

UPDATE: a friend and I tried everything and couldn't find a reason. But we turned the module upside down and stood it up and it works. I'm going to try it at practice to make sure but it hasn't cut out yet. I don't know why
 

dilithium85

    best pics I could get

Danny1969

See those large white rectangle things on legs  ... those are ceramic resistors. Check the solder joints on the bottom. You can get a situation where the weight of the resistor will cause the joint to work in one position but not in the other orientation.

It's good news though, almost certainly a bad joint

dilithium85

Thanks I'll get someone better at soldering than me to give it a go

jpfamps

Looks like a job for that most useful of dianostic tools: the chopstick.

dilithium85

jpfamps said:

Looks like a job for that most useful of dianostic tools: the chopstick.

I do have a range of pokey things but I'm always careful where I put them