Senn 421 Cutting Out

[stetto]

I'm just a mess, ain't I?

I picked up a used 421 II a couple weeks ago and have been lovin' ev'ry minit of it, right up til this morning...It started to "cut out" when the signal is low or nil, but comes to life instantly when I shout or play a hard chord on the acoustic...This occurs at all positions of the roll-off switch. When it cuts out, it does a rapid fade, almost like a limiter would, but cuts back in instantaneously. There is still a very muted signal getting through when it's "out".

To make sure that it wasn't a problem with something else in the signal path I ran several mics and instruments through the same channel with the same settings, via the same mic cable--Only the 421 is doing this, but only intermittantly--It will go for 20 minutes without a problem, then just--cut out...There is no compressor or limiter in the signal path.

I'm thinking bad capacitor in the mic, but I'm less than a novice at things electronical, and have no clue as to the circuitry of a 421...

Any help out there?

Eric

 

[northsiderap]

Novice Repairs

Novice level repairs usually include:

Taking it apart looking for obvious loose connections, bad solder joints, or burned spots. Make sure you can get it back together EXACTLY as it was before.

Try that first...

 

[stetto]

northsiderap;

Once you get get to know me, should the necessity arise, you will find that I do possess the idiot savaunt aptitude for putting things together exactly as they're taken apart...

I have some background in Stone Knives and Bearskins electronics, am nominal in my soldering skills, and even used to be able to read the little color-coded bands on resistors and such...But I haven't dealt with a circuitboard in some years and had some little hope that one of the brain surgeons here might be familiar with the symptoms described. Bar that, I am prepared to do just exactly what you prescribe...Thanks for your input.

Eric

 

[stetto]

So then, for future reference for anyone else experiencing the problem I did;

One of the diaphragm lead solder joints was cracked but not broken. How it got cracked is a mystery to me, as there is plenty of slack in the wire and the crack doesn't seem to be caused by stress to the joint. Once resoldered the mic appears to be functioning normally...One for your side, northsiderap...

I had a wonderful adventure disassembling this mic. I don't recommend it to anyone unless absolutely neccessary...

Eric

 

[northsiderap]

Good!

I'm glad you got it working - - - They are fun mics.