Noobie needs FET advice... I think

[CJoooooooo]

Hi guys! I'm looking for some advice on replacing what I believe to be an FET that was externally fitted to an old-ish USB mic.

Quick summary of it's life.
Purhased it for gaming a good while back, found it too quiet so I ripped the microphone out and directly wired it to a jack. Switched it out for a headset mic.
Fine for a couple of years but then I think i had some grounding issue.
Behind the mic was a small pcb about 1.5 by 1 cm with a small 3 pin component on it, which i believe was the FET.

While cleaning up the soldering the copper came away from the pcb and broke one of the legs to this component.

The mic itself is fine I just need to figure out what the replacement part is.

Unfortunately there's no readible numbers on the component.

I've included a picture of the mic, A drawing of the component and a link to the actual original microphone.

https://www.worthpoint.com/worthopedia/prosound-a99jb-usb-0-hq-podcast-vocal-523124932

Any help would be grately appreciated.

Chris

 

[Voyager10]

In that long-legged package the most likely-looking match I could find is a 2SK1109.

The FETs used in electret mics have a built-in resistor (or equivalent) to set the gate bias. Other FETs like this include 2SK596, 2SK660 and TF202.

You may have trouble finding any of these at a sensible price, and TBH you may be better off with a new capsule. In the UK, micbooster.com sell a good range of Primo capsules which should do the trick.

 

[CJoooooooo]

Are ebay listings of fets not to be trusted then?

 

[pucho812]

Are ebay listings of fets not to be trusted then?

It depends who is selling them. General rule is to go with known sources like mouser, digikey, etc.
If you can’t find a part try octopart search engine and go from there

 

[CJoooooooo]

In that long-legged package the most likely-looking match I could find is a 2SK1109.

The FETs used in electret mics have a built-in resistor (or equivalent) to set the gate bias. Other FETs like this include 2SK596, 2SK660 and TF202.

You may have trouble finding any of these at a sensible price, and TBH you may be better off with a new capsule. In the UK, micbooster.com sell a good range of Primo capsules which should do the trick.

I did as you suggested and it's not the same.
I purchased an identical mic capsule with a fet already installed. still incredibly quiet.

I now have no idea what this super fet was on the back of my old mic

 

[Voyager10]

So maybe the problem is not with the capsule at all?

What is the capsule actually wired to, when it's not working? Pictures might help.

The capsule will need to have a power supply in the 3-5V region connected via a load resistor in the region of 2K. PC 'mic' sockets normally do this, but maybe there's something odd with the connections.