Kookie's Blue Kiwi repair thread

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SoundsOfJill

Member
Joined
Apr 20, 2023
Messages
19
Location
Bayonne, France
Hi there everyone!

I just got my hands on a Blue Kiwi, sold for parts, at a very very good price. I plan to repair it and or transform it into a usable studio mic again! And so, since it seems most people here share my enthusiasm for troubleshooting mics and saving studio gear from the landfill I figured I'd share my progress in a thread.

Part 1: Assessing the damage

My first order Lollipop.jpgof business was unboxing the mic, packaged in it's original cardboard box, 13 years after it rolled off the production line

Box.jpg
The mic itself was in great cosmetic condition, no big scratches on the body. I gently rotated the mic with my ear to the headbasket, to quickly check for a dislodged capsule: no sound. good.
I mounted it to its shockmount, then fastened it to an arm on my desk, plugged it in to my interface and turned on p48. The meter does a weird dance. I bring up a DAW to audition and record what it's picking up: "KSHHHRRRoneRRRRRRhello? POP check check POP POP hello ? One-Two. Hey it wo-SHHHHHRRRRRRKKK POP POP"

I rotate the the pattern selector, each click seems to trigger a bit of the noise, but it trails off eventually every time, leaving the mic nearly usable.

Now, I don't claim to be an expert. But it's not my first "it's broken" mic that I buy (broke girls make due). And it's not the first time I hear that sort of noisy behavior from a capsule. My current hypothesis: this mic has been sitting in very humid storage for a long while now and the mylar of the capsule is nice and hydrated by now.


"But Jill that's such a wild guess, it could be anything!"
Yup, it could. But the oxide on the hinges of the box is a bit of a tell that I should try to at least eliminate humidity. Also for now unmounting the capsule-basket assembly and placing it in can with silica Hinge.jpgon the bottom is free, and can be done overnight. I was also going to check the electronics for dead caps buuuuHot Glue.jpgt. Well let's just say Blue didn't intend for people to dissassemble the mic. Ever complained about the bad metal work in the frame of a mic on this forum? Then buy a bunch of Blue Kiwis! This is a mic without a frame! The PCB is literally held to the tube of the body by beads of hot glue. I wish I was joking. It's a beautifully machined 2000$ mic, but I guess they couldn't be bothered to make it pretty on the inside.

Anyway, I'll see if the drying has done anything and keep y'all updated.

If the capsule is a dud, what should I replace it with? I would love to hear your suggestions!
 
Part 2: Further Investigation and Cut Corners

Happy Thursday everyone!
After leaving my capsule assemble in silica and near heat overnight I put it back on the mic aaaaand:
"KSHHHHHHHHHHHHHHHHHHH"
yay.

Well repairs can't always be easy, right? I then got to work disassembling the mic. Remember the hot glue joints from yesterday? Welp they're no issue. They're loose! Who could have guessed hot glue wouldn't stick well to unfinished steel? The PCB is actually mounted to the bottom... coupling? Assembly? The end cap with the XLR. There's two screws going through it.

Ok good. Sooo I guess I just have to pull it out. Oh no of course the pattern switch is gonna prevent me from this. I just gotta take a guitar pick to lift it and.. no budge.

I inspect further down the dimly lit body tube and I spot a tiny hex screw keeping the thumbwheel on the pot. Great.Pot.jpg
So. Until I can find a long enough M0.5 ish hex wrench it's not coming off. I just give the PCB a visual inspection from the awkward angle and... it looks like the traces to the capsule connector have been scratched out then soldered over by hand???
Is that from the factory? Maybe after a certain amount of returns they decided it was best to do so for.. impedance reasons maybe?

The resistors are also weirdly soldered. It looks like they maybe ran out of axial resistors for these values and had to improvise with radial ones?
WTF2.jpgWtf1.jpg

Oh well, capsule time! It's everyone favorite part! *Velma Voice* Let's see what see what kind of capsule hides behind this grille! Front cap.jpgRear side.jpgRear.jpg

It looks okay at first glance, dirty I guess, but it's a mic from 2012 so it's bound to have gathered stuff. Interestingly it's set in a way where the capsule protrudes out towards the rear of the mic. It looks like it's a double backplate design, it reminds me of a k67 but that's my newbie eyes talking I guesDent 2.jpgs.

Oh? What's that on the front? It looks like there is a dent on the diaphragm maybe? I could be wrong, again I've only been tinkering with mics for about a year by now, so I've still got much to learn.
What do you think Scooby-Gang
, could this be the culprit?

Here's a recap of our case so far:
- The mic was manufactured in 2012
- The previous owner claims it stopped working from one day to the next
- When under p48 the mic outputs noise
- When the pattern select pot gets turned in rapid succession the noise can suddenly cut and signal can be heard (though weak), for a few seconds, before the noise comes back
- The mic was cleary never engineered with maintenance in mind

I'm off to get groceries and hopefully find a wrench that will work. In the meantime, Scooby Gang, will you help me solve this mystery?
 
Does the microphone behave the same in all polar patterns?
Is that dent on the front diaphragm? Have you tried reversing the front and rear diaphragm wires?
Could it be contact problems, oxidation, at the switches?
Someone intervened in the microphone and seems to have left a mess. The high impedance input area should be cleaned with isopropyl alcohol.
 
Does the microphone behave the same in all polar patterns?
Is that dent on the front diaphragm? Have you tried reversing the front and rear diaphragm wires?
Could it be contact problems, oxidation, at the switches?
Someone intervened in the microphone and seems to have left a mess. The high impedance input area should be cleaned with isopropyl alcohol.
Yeah I noticed the flux when I edited the photos earlier. That's getting cleaned as soon as I can get the PCB out.
The dent is on the front diapragm, the mic seems to behave similarly in all patterns.
Before I start de-soldering wires to swap them I wanna fully assess the PCB. I'll escalate the measures I take as I go. Though I'm gonna have to figure out how to dissasemble the capsule assembly fully and hope it's not glued
 
It's not a dent, it's a puncture. With the edges pushed inwards. So it looks on the photo. I guess they short out on the backplate.
Disconnect the central wire to the damaged membrane, when you gain access to the pcb, and see listen what happens.
 
It's not a dent, it's a puncture. With the edges pushed inwards. So it looks on the photo. I guess they short out on the backplate.
Disconnect the central wire to the damaged membrane, when you gain access to the pcb, and see listen what happens.
that's the fun bit. The capsule is connected to a tuchel-esque 4 pin female connector in the assemble of the headbasket, that connects to the male connector you see on the edge of the PCB photos. I think I'm gonna have to use alligator clip cables to try that while the mic is open. To connect the rear diaphragm to the front diaphragm's pin.
 
that's the fun bit. The capsule is connected to a tuchel-esque 4 pin female connector in the assemble of the headbasket, that connects to the male connector you see on the edge of the PCB photos. I think I'm gonna have to use alligator clip cables to try that while the mic is open. To connect the rear diaphragm to the front diaphragm's pin.
In this case you will probably have a rather loud hum. But it would be a confirmation that the electronic circuit is working.
 
Part 3: The plot thickens

Quick little update: I asked the previous owner if someone had touched the mic and learned that it was sent to a microphone repairperson, who sent it back saying they couldn't fix it.
I don't know when the capsule got punctured, but likely the weird mods and excess flux came from that.
 
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