MK-319 distortion when phantom power is engaged

[sneakyybstrd@Aol.com]

I have an MK 319 that when phantom power is engaged, i get my voice pretty clear for a few seconds, then i hear a noise floor get boosted, and my voice gets more quieter distorted,fuzzy until i cant make it out, its just quiet fuzzy muffled voice very faint. Then when i turn off the phantom, I can actually hear my voice clear again for like 1-2 mins, like its a dyanmic mic or something lol. And it works until I boost the gain higher and higher and then my voice goes away and there is no sound. Any ideas lol. The capsule is very dirty Im sure that it is causing some problems, its got dust particles, saliva splats. I cleaned the board was pretty dirty but created no improvments. Im waiting for dionized water and some kolinksy brushes. the center termanal on the mic capsule i noticed is loose a bit but scared to tighten it.

Any ideas? Ty

[Jimmy B]

Since no-one else has picked this up...
I don't have one of these, but it looks like quite a simple circuit.
I would investigate the following things, in ascending order of difficulty:
1. A faulty cable- swap it for another. Not very likely but easy to do.
2. Corroded contacts - scrub them all with switch cleaning fluid (methylated spirit is better than nothing at a pinch) and a cloth or artist's brush . Then make and break them repeatedly to clean them. All of them.
3. The loose contact- investigate and tighten it if necessary
4. A dry joint on the circuit board. Locate and resolder.
5. A component that it breaking down at high voltage- most likely a capacitor. Replace it.

If you don't feel comfortable with 3, 4 and 5, you may need to find an electronics technician who is.

[SimonZ]

The capsule is very dirty Im sure that it is causing some problems, its got dust particles, saliva splats.
Any ideas? Ty

That is the problem.

When combined with moisture from your breath (or the room if humid) the dirt on the capsule creates a conducting path to the grounded edge of the capsule.
The charge on the capsule drains away.
Creating lots of noise and loss of signal as it happens.

Then after some time to dry out the signal will come back.
Then when you breathe on it again the cycle repeats.

Capsule cleaning is not an easy task.

[Jimmy B]

The capsule is very dirty Im sure that it is causing some problems, its got dust particles, saliva splats.
Any ideas? Ty

That is the problem.

When combined with moisture from your breath (or the room if humid) the dirt on the capsule creates a conducting path to the grounded edge of the capsule.
The charge on the capsule drains away.
Creating lots of noise and loss of signal as it happens.

Then after some time to dry out the signal will come back.
Then when you breathe on it again the cycle repeats.

Capsule cleaning is not an easy task.

Yes, that looks more likely to be the source of the problem than the things that I listed.
For the benefit of the OP, does anyone know how you would go about getting a capsule cleaned?

[Drew Stephenson]

I think I'd start by going back to the Oktava distributor in your country. Unless you know of a local mic mechanic with a good rep.

[Philbo King]

You might try putting s few packets of silica gel in the case with it for a couple weeks.

[Wonks]

You might try putting s few packets of silica gel in the case with it for a couple weeks.

Unfortunately that won't remove the contamination on the capsule/electronics board. The moment humid air hits it again, more moisture will be absorbed within a few minutes and provide a leakage path from the high impedance circuitry to ground.

I know that SimonZ is amongst other things, a professional mic technician, and will have worked on many similar mics. If there was a simple fix, he'd know.

[Mike Stranks]

I know that SimonZ is amongst other things, a professional mic technician, and will have worked on many similar mics. If there was a simple fix, he'd know.

Yup! Simon really knows his stuff - and is not given to overstatement. If he says it's complicated... it is!

[SimonZ]

Blushing now
I did say 'not easy', but it's not complicated so much as just slow and careful work.
The kind of slow and careful that can eat up a good proportion of a budget mic's value.

So for anyone who wants to DIY (at your own risk, but hey, the capsule is bad at this point)

You need a very good quality fine tip sable hair artists brush, the kind that has just a couple of hairs at the tip.
Strong magnifying glass or watchmakers loupe.
Distilled water & some strips of very fine tissue paper.

Mask and gloves recommended and some way to hold the mic very still.

The most problem causing bits of dirt are in that small ring with no gold at the edge. The bits there create the bridge to ground for the moisture.

Choose your speck of dust.
Dip the tip of the brush in the water and put a tiny droplet of water on that place. The water droplet will sit up on the surface like a small glass bead.
If you are lucky the offending dirt particle will float off the surface and into the water drop.
Then touch the corner of the tissue to the water.
It will soak up the water drop and usually take the dirt away with it.
Start breathing again !

Then repeat until you are done, may take hours.

(if you get any water under the clamping ring at the edge, you are in trouble)

Dry the mic for a day and then give it a test.

As you can imagine, for most cheaper mics it is way more economical to swap in a new Chinese made capsule.

Somewhere on the net there is a much better description by David Royer or Josephson, I'll try to find it.