[Kenwood] Kenwood TS-950SD Blowing 10 Amp Fuse on the Final Board

[Tom Prohigh]

I had a similar problem with my TS-950SD.  The pass transistor decided to
short and send unregulated voltage through the finals.  Needless to say, I
had to replace the pass transistor and the finals(ouch).  I think your pass
transistor is possibly shorted and finals may be OK.  Mine did not blow the
fuse.  You can get the parts from RF parts.  The pass transistor is
manufactured by Sanken : 2SC2922.  It is about 1.5" by 3/4" and on the final
board.  At full output it is dissipating about 250W.  It drops the
unregulated from about 80V to 50V with a current of 8A.  Buy a few extra so
you have a spare.

Tom - AB3FL


Message: 2
Date: Sun, 27 Feb 2011 19:50:47 -0500
From: Durl Grant <zf1dg at candw.ky>
Subject: [Kenwood] Kenwood TS-950SD Blowing 10 Amp Fuse on the Final
	Board
To: kenwood at mailman.qth.net
Cc: Wenty Bethune <wbethune at gmail.com>
Message-ID:
	<AANLkTik32DB+fRJpvdpqUqnJGNB-GtkK-jgWkcRZDXg6 at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Hi Group,

I am posting this on behalf of my friend Wenty 6Y5IC (his computer is
currently down). He has 2 - TS-950SD's and they are both blowing the 10 Amp
Fuse on the Finals Board.  The radios will power on and stay on but will not
transmit. He has replaced the fuse on several occasions , but when he try to
TX there is no output, so the fuse is either blowing when he
powers up or the second he goes into transmit.  When he checks the fuse is
always blown.  The other 950SD does the identical thing.  It's ironic that
he has 2 - 950SD's with the same identical problem.

Could it be that the Output Transistors (Finals), are shorted, or is
something else on the Finals Board is shorted that's causing the fuse to
blow?

If anyone has experienced this problem I would appreciate hearing how you
resolved it.  l looked at quite a lot of the Threads in the Archives but I
didn't find anything that relates to this problem.  Of course I didn't
read all the archives, and there's always the chance that I missed it on
those that I did read, which was quite a lot.

Your assistance with this issue would be very much appreciated.  Thank you.

73,

Durl, ZF1DG