K30a pinout

[petemoore]

  I found it's probably a Jfet, NTE458 replacement, but I couldn't find a data sheet or pinout info.

[Gilles C]

http://www.datasheetarchive.com/pdf/2sk30a-datasheet/2sk30a-datasheet.html

[petemoore]

  Thanks Gilles C !
  Looks like SGD, transistor facing me pins down.
  I didn't see much, must be a general purpose Fet...that's cool!

[MartyMart]

My Toshiba 2SK30ATM data sheet says D-G-S flat side to me and pins down.
Only ever seen them as switching fets in Ibanez/Boss pedals, there are
quieter and better things to use, though I've never had a "noisey" or even an
obvious tone sucking pedal from those two companies !!     go figure

MM.

[lowstar]

they can be in the signal path too, like in the oc-2 for instance.
and there, they do make a difference IME. my oc-2 clone did not sound quite right with 2n5457 or j201, but opened up once i got the 2sk30a. if you look at the datasheet, you see that the other "replacement" fets are not a perfect match.

cheers,
lowstar

[petemoore]

  These came out of some Multi effect units I've been repairing, cheep switches are cool !!! 3 switches in each, wah chorus dist, when one goes bad I get two good switches a rocker with a 100k pot, 5 x 100ka, 1 x 500ka [nice chrome knobs]...the k30a's, some BCxxx, other Si npn's..
  Looked like a well designed multi circuit box, except the 'fall apart' switches...I think 3 of 5 of these multi effect units [a friend of mine got in on a bulk order] had a failed switch within the first 6 mo., unfortunate.
   I don't know why I want to mess with the k30a's other than they're there, different pinout than J201/2n5457/MPF102...looks like the gate is in the middle, I can probably get EZ Bias on it just assigning the Q's middle socket pin to gate...that should do it !!! Thanks for the help guys !

[TheBigMan]

You'll find those in the buffer sections of a lot of older Boss pedals as well as in the switching circuitry.  Decent enough FET, I only keep a stock for repairing Boss and Ibanez pedals cos it's easier with a straight swap on the pinout.

[Gilles C]

I bought some many years ago to built and experiment with Boss type switching instead of true bypass.

When I noticed they were also used as buffers, I began to use them in preamp circuits and found they had good specs.

Having some FETs with different pinouts is what started me on using a 4 pins socket in my circuits to be able to use any pinout.

Gilles

[petemoore]

  Having some FETs with different pinouts is what started me on using a 4 pins socket in my circuits to be able to use any pinout.

  Easier than twisting the s/g legs eh? Fewer broken transistor legs ?...cool idea!
  I got lucky with the second Sparkleboost in a week [2 sound great, one 'before / one 'after], I run low on resistors so put a 10k on drain + 100k trimpot [smallest I had above 5k], and it turns out the J201 biased very closely to 1/2v with the 10k !!...there it stayed, socket or not. Sounds great too, harder/higher gain than the 2n5457'd SB.
  I thought I might want to try some of the found k30a's...not too worried about that now.