[sdiy] strange analog problem (mixer console)

[ChristianH]

Hi Nils,

could it be some fishy coupling electrolytic, that needs its ears to be
blown free from time to time? They tend to do funny things when they get
old (Ok, we all do...).

cu (at least I hope so, Bad Berka II is waiting ;-)
Christian




On Tue, 15 Apr 2003 12:25:16 +0200 Nils Pipenbrinck wrote:

> My Behringer mixer - after several years of duty - has some strange problems
> lately.
> 
> I just wonder if anyone of you have experienced a similar effect or knows
> what's wrong.
> 
> 
> When I turn it on the right channel is dead, regardless which input I use. I
> can measure the signal, but it's only a tad higher than the usual noise
> floor and distorted. The pots, faders and switches are fine.
> 
> However, I can "activate" the right channel again by running a hot signal
> into it (9V battery does this job). It makes "plopp" and then the right
> channel comes to life again. It'll also stay alive as long as some signal is
> present (usual audio, not the 9V). I'm still happy with the mixer. After
> resurection it sounds as it always did. Just the "kick in the butt"
> procedure is anoying.
> 
> Btw, if I stop using it for a while (no signal at the inputs, but chords
> connected) the right channel will go dead again.
> 
> Does anyone know what could be the cause of this? My only guess is a heavy
> dc offset between the devices which cause the opamps to latchup, but that
> would not explain why only he right channel is dead, and why the resurection
> works.
> 
>   Thanks,
> 		Nils
>