Destroyed front diaphragm on a brand new K67

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I was able to repair a friends U87 by flipping the capsule back to front , it had become contaminated and he'd tried to clean the front side . Worked just fine on cardioid after.
 
I tried grounding both the backplate and diaphragm to discharge any static. No change. I left it sitting open on my workbench, with the diaphragm facing down, to let the moisture (from blowing on it) dissipate. I went to put it away and a lot of the marks are gone! It still measure poor, but 160pF vs the 500pF that is had been.

I'm not expecting this thing to return to normal, but I'm gonna give it some more time and see what it does.

@k brown, you may be right about the mylar. Could it possibly be the gold that was holding shape? Maybe the Mylar is taking its shape back.
Is it k67 or k87? I hope you measured the capacitance between the two backplates before separating them. Presuming they are electrically insulated. Microns in diferences of the spacing can mess with the performance considerably. Yes there is a spacer there, but overtighting or undertighting will still affect the distance. Not to mention you have to take care nothing gets on the spacers, or backplates. Dust, hair, buggers, i've seen much crap getting stuck there.
 
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I think the high voltage short-circuits the diaphragm and the copper plate, causing electrostatic adsorption. Even if the physical appearance of the diaphragm is restored, it is difficult to restore the previous tension after the diaphragm is stretched, and the frequency response may change.


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Is it k67 or k87? I hope you measured the capacitance between the two backplates before separating them. Presuming they are electrically insulated. Microns in diferences of the spacing can mess with the performance considerably. Yes there is a spacer there, but overtighting or undertighting will still affect the distance. Not to mention you have to take care nothing gets on the spacers, or backplates. Dust, hair, buggers, i've seen much crap getting stuck there.
I think it's a K67. I believe the spacer between the backplates is conductive. Pretty sure the backplate terminal was terminated to one backplate with a single screw.

I did not measure between the backplates. I'm hooped there. Not that I'm okay with it, but I'm expecting a less than perfect performance in omni/fig8 since one side is damaged. I may need to reskin it anyway.
 
. . . forgot the bloody pop screen!
Something like that. I was using compressed air to get lint off the capsule, and in a moment of complete inattention, I swung the canister around behind the capsule, which positioned the jet at 90 degrees, rather than the usual approximately 170 degrees. It was all over in a millisecond... OK, lesson learned.
 
i use the type of brush they use to clean antique gold leaf for this. usually white goat hair. you can find them from museum equipment suppliers
How do you clean it? Alcohol? Water? Another goat?

I've used a fine makeup brush before but not enough that it's dirty yet. I'd invest in a better brush, but I'd want to be able to clean it safely.
 
I havent pulled a working LDC appart , but one thing struck me , it probably makes sense to mark the alignment of both the backplates and their respective membranes, spacers before you go at it . So everything goes back to exactly as is left the factory .
This capsule actually has two tiny plastic rods that sit in holes to line them up.
 
How do you clean it? Alcohol? Water? Another goat?
I don't, generally. If it needs cleaning that isn't just dusting, it's covered with salt or oil, and that's complicated. The capsule hopefully doesn't get to this state, but it depends on usage. Worst capsule I ever got on the bench came from some dude who smoked weed so often that it was caked in weed oil that had deposited as droplets from his mouth over the years. It was multiple times thicker than the membrane. Unbelievable.
 
I don't, generally. If it needs cleaning that isn't just dusting, it's covered with salt or oil, and that's complicated. The capsule hopefully doesn't get to this state, but it depends on usage. Worst capsule I ever got on the bench came from some dude who smoked weed so often that it was caked in weed oil that had deposited as droplets from his mouth over the years. It was multiple times thicker than the membrane. Unbelievable.
Ack! That's disgusting. Buy him a pop filter and a toothbrush.

My post wasn't clear, I meant cleaning the brush. I don't clean capsules with water, I just lightly brush off the dust if it's starting to accumulate. Figured buying a better brush would be smart, but I want to clean it after use.
 
Ack! That's disgusting. Buy him a pop filter and a toothbrush.

My post wasn't clear, I meant cleaning the brush. I don't clean capsules with water, I just lightly brush off the dust if it's starting to accumulate. Figured buying a better brush would be smart, but I want to clean it after use.
natural hairs are best cleaned with only water i think. you really don't want to strip them of their protective layers. if it's stubborn, try a baby shampoo
 
. Worst capsule I ever got ... from some dude who smoked weed so often that it was caked in weed oil

EEee-yuk.

Hmmm ... are you sure it was actually weed oil, and not polyunsaturated cooking oil from all the munchies he must have consumed after smoking . . . ? That might require a different "tack"? :) Anonymous
 
natural hairs are best cleaned with only water i think. you really don't want to strip them of their protective layers. i

I agree - and if it gets really nasty, I recommend getting another brush as they are low cost compared to the value of the item you are cleaning.

I understand some have tried specialized foam camera sensor cleaning brushes with a very light touch. Those are usually tossed after a single use. Not cheap at around $2-$5 each, yet low cost compared to the cost of a professional cleaning ($75) or full frame replacement sensor ($500) - just my take. James
 
EEee-yuk.

Hmmm ... are you sure it was actually weed oil, and not polyunsaturated cooking oil from all the munchies he must have consumed after smoking . . . ? That might require a different "tack"? :) Anonymous
the capsule itself smelled so strongly of weed that i had to keep the backplates in a plastic bag
 
Once upon a time, I was going to purchase a Studer mixer from a guy so I went to see it at his house. He had smoked so much weed that not only were the outer mixing surfaces coated in resin, but the inner circuit boards too. I didn't think I could ever clean it well enough, and so passed on it. His weed smoking was a terrible thing to do to such a fine piece of gear.
 
Once upon a time, I was going to purchase a Studer mixer from a guy so I went to see it at his house. He had smoked so much weed that not only were the outer mixing surfaces coated in resin, but the inner circuit boards too. I didn't think I could ever clean it well enough, and so passed on it. His weed smoking was a terrible thing to do to such a fine piece of gear.
so rude after he went through the effort of conformal coating it for you over all those years............. ;)
 

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