A couple of questions to ask you:
1) Are you in a high-humidity environment?
2) What kind of preamp are you using that is supplying phantom power to this mic (the Tascam?)? Does the problem still exist if you only have that 1 mic connected to the mixer?
3) Have you tried swapping out cables?
4) Any possibility of a strong RFI or EMI source being in close proximity to that mic (video/PC monitors, flourescent lights, cell phones,etc)?
A bad cable can cause a phantom-powered mic to pop and crackle as the intermittent connections make/break. I have had condensers do that number when the relative humidity is way up, and have read that it involved the nature of the permanently-charged element some of these mics (including the Shure KSMs) use.
You should also check with the manufacturer. Shure has a very good website and they offer great tech support.

Yes its high humidity, Puerto Rico.... i've manage to seal up the room very efficently and i have air conditioning , but i suppose i've considerable humidity. Second, yes I use Tascam's phantom power, and no additional mic preamp... Its thank a considerable fact? using tascam phantom power?, I haven't tried only connecting that one mic, but I'll get to it certainly. One thing I do have that maybe a problem its that I have exposed electrical circuits, on the outside of the wall, on metal tubes of course, but expose, and there are three double sockets , each one with double circuits, so theres heavy electricity traffic, but when recording none of these where active(nothing pluged), and even with the lights out, i ve got heavy buzz sound and pops. I didin't thought that was going to a problem. I've have some hallogen track lights, but as I said before, even with the lights down I have buzz and pops. What do you mean by swapping out cables?, all my xlr are new as the mic and the mixer...

Thanks for the advise moonbaby, I will get to these facts and also get back to you if I found some problem solving....
THANKS A LOT.....
BBTODRUM

Youmentioned that you have "halogen lighting"...this is a "low-voltage"type system and the dimmers CAN certainly be a source of buzzing interference. In fact, the more the lights are dimmed, the worse the interference can be. If you can kill the lights at the circuit breaker, that might help isolate the problem. My suggestion to swap mic cables was to see if it made a difference. But if your problem is more of a "buzzing noise" I think that you have a source of interference (RFI or EMI), maybe a grounding issue to be addressed. You might take the mic, the Tascam, cables, and headphones out to another site and see if the problem persists. I also am concerned about your description of the electrical wiring, with the conduits and outlet boxes exposed. Wierd question: does the buzzing change if the mic or the cable positioning is changed in relationship to the outlets? Is your audio gear near the light dimmers? Are both the audio and the dimmers on the same electrical circuit? I am suspect of that portion of the studio....lighting diimer circuits can wreak havoc on a studio...

thanks moonbaby for your thoughts and replys. I tried moving and changing sites, but its deffinetly the Sure thats giving a weird sound, like some wind going through it.( I had air conditioning turned off) I tried only having one mic a a time with out the snake(I use a snake, six channels, two sends), and It solve the buzzing with the sampson mics and a SM58, no buzzing at all with those. I also move them through out the studio and through the hallogen lights, even the electrical boxes, and had no effect at all. So I guess the KSM 27 is giving me some weird trouble. I still want to try it all before I make any moves towards sending it back , any suggestions.....

this mic had a loose wire that connects to the cardiod plate. Sweetwater tried to repair it first, so they sended it to Shure, but came back and in two seconds after recording began,, it started behaving with the same simptoms. So I sended back again to Sweetwater and they did what had to be done, REPLACEMENT, they were very kind and shipped back a completly new KSM 27. This guys are great, best service ever.....

this mic had a loose wire that connects to the cardiod plate. Sweetwater tried to repair it first, so they sended it to Shure, but came back and in two seconds after recording began,, it started behaving with the same simptoms. So I sended back again to Sweetwater and they did what had to be done, REPLACEMENT, they were very kind and shipped back a completly new KSM 27. This guys are great, best service ever.....