Are your final tubes fine after C13 short?; that failure will turn
very positive final tube's grid bias, which causes an indeed high plate
current. Check them before you go to the shop. If I don't miss, C13 was
a 100 pF rectangular old style mica cap. You could replace them with two
47 pF, 500V NP0 disc ceramics in parallel as I did in several 101's with
good results.
Best regards
Guillermo - LU8EYW.
Jerry Pittman wrote:
Correction!!! Sorry Rick, I spoke to soon. I pulled the C13 cap from the
circuit and found that it had shorted. You were dead on for the diagnosis.
Now to go to the electronics shop tomorrow.
Thanks a Million!!
73 Jerry
WD4OIX
----- Original Message -----
From: "Jerry Pittman" <jerryp49@worldnet.att.net>
To: "R_Davis" <WD8JJA@arrl.net>; <yaesu@contesting.com>
Sent: Sunday, February 15, 2004 5:59 PM
Subject: Re: [Yaesu] Problem in FT-101E -100v Circuit (Jerry Pittman)
Thanks for the tip Rick. I checked that cap and it appears okay, so the
search goes on.
Jerry
----- Original Message -----
From: "R_Davis" <WD8JJA@arrl.net>
To: <yaesu@contesting.com>
Sent: Saturday, February 14, 2004 12:41 PM
Subject: [Yaesu] Problem in FT-101E -100v Circuit (Jerry Pittman)
Check the coupling capacitor, C13, between the 12BY7A and the finals.
Rick, WD8JJA.
----- Original Message -----
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To: <yaesu@contesting.com>
Sent: Saturday, February 14, 2004 12:00 PM
Subject: Yaesu Digest, Vol 14, Issue 9
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Today's Topics:
1. Problem in FT-101E -100v Circuit (Jerry Pittman)
----------------------------------------------------------------------
Date: Fri, 13 Feb 2004 12:41:26 -0500
From: "Jerry Pittman" <jerryp49@worldnet.att.net>
To: <yaesu@contesting.com>
Subject: [Yaesu] Problem in FT-101E -100v Circuit
Message-ID: <006e01c3f258$9b485ac0$6101a8c0@JerryPittman>
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Reply-To: Jerry Pittman <jerryp49@worldnet.att.net>
Message: 1
Hello to all,
HELP! I wonder if anyone has run into this problem:
My 101E was just idling along while I was working on the computer the
=
other evening, when I started smelling something hot. I shot the rig
=
off immediately and found that the bias control (VR1) on the voltage =
control board (PB1547B) had over heated, as well as the (2) 10K =
resistors on either side of the control.
When I check the voltage at pin 5 of the 1547 board, I found that it
was
=
getting -160v instead of -100v. I went to the Rectifier board
(PB1076B)
=
and made tests there. When I disconnected the lead from the -100v =
terminal, the voltage shows -60v but with it is connected it shows =
-160v. With the lead disconnected I also tested it for AC voltage and
=
it shows 125vac as well as -60vdc.
I checked all the components on the 1076B board and found all okay,
but
=
just to be sure I hadn't missed something, I put in a used PB1076B
board
=
and found all of the same readings. I had already checked all of the
=
other voltages coming and going from the 1076B and all are correct =
except the -100v. The voltages from all of the transformer taps
appear
=
to be within range as well.
Does anyone have an Idea or run into this before?
Thanks in advance for any responses.
Jerry
WD4OIX
jerryp49@att.net------------------------------
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