Go back into the archives to Feb 21, 2016 for Centurion 422b troubleshooting
help needed". My Centurion showed 140ma plate current when unkeyed in standby
mode. Found the bias xistor Q1 on the FILAMENT-AC BOARD to have failed. Q1 in
my amp was a MJ15001 from "ON" (mfr) date coded 0318. Failuer analysis on the
failed Q1 revealed serious, gross conditions on the die that should have been
revealed during pre-close inspection of the xistor. Die was damaged
extensively, but it took many ours of operation before the die failed
catasprophically.
If the failure symptoms I described in my 2/21 post mirror those that you've
encountered, I'd look closely at Q1. Is it a MJ15001? If so, mho mfg it, and
what's the date code?
I replaced Q1 in my Centurion with a JANTX 2N3055. It's been performing
beautifully since late Feb, and runs very cool...and NO plate or grid current
when in STANDBY mode. Replacing Q1 is a real PITA. Don't lose the tiny nylon
shouldered washers for the Q1 mounting screws, or the (hidden) steel washer
that's located in the center of the board between the two assemblies that have
to be separated to access/replace Q1.
Good luck, and best 73...
Allen--W7GIF
----- Original Message -----
From: kr2q@optimum.net<mailto:kr2q@optimum.net>
To: tentec@contesting.com<mailto:tentec@contesting.com>
Sent: Thursday, May 26, 2016 4:16 PM
Subject: [TenTec] Centurian amp...more info..and more questions
Hi again
I just reread the QST review article. I now note that they cited plate idle
current when the
amp was in OPERATE but not keyed.
My amp shows idle current while in STANDBY.
Does that lead to any clues as to what might be "wrong?"
Also, SN is 09A 10027. What year is that from?
Thanks again,
de Doug KR2Q
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|