John Bowers Active 1

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Don’t know where to post this; it is both solid state and speakers.
Anyway the problem is about transistors so here I go:

Got a pair of these speakers from a customer, brought in for repair years ago.
After telling him the price for repair, I never saw him again.
Years have past now and I just decided to try to fix those speakers for myself.
The name says Active, which means they are powered speakers.
Picture 21-23 at
http://home.pi.be/~nzc641/inhoudmenu/setlijst/jacques thys/jacques3.htm
are about the only pics I could find on the net.
The mosfet amplifier has 2sj99 and 2sk343 devices in it.
Possible replacements could be 2SJ82/83, 2SK226/227 but they are also not easily available and their pin out is different.
So, the question is obvious:
Would anyone here on the forum be able to point me in the right direction (replacements) or maybe someone has those fets lying around and is willing to sell them.
I need two of each.

Many thanks

/Hugo
 

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john bowers active 1

From my pair of speakers a few tips.
One of them became unstable, and switched itself on and off intermittently.
Problem was in the regulator on the filter board - both capacitors had dried out, and read zero mfd - they are very close to both high power resistors and hot running transistors.
Try changing them to high temp working ones.

The other thing I noted is that the HF mosfet amp does produce a small dc voltage across its output - not a good idea for feeding a tweeter, and a fault condition could write it off.
I have located some 2sk343 transistors, and if anyone would like to share a part order ( 10 is the minimum I can order) please shout !
I also think that I have found modern day more robust mosfets to change the 2sk343 and 2sj99's.
 
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