[TenTec] Centurion Amp. Problem

[Donald, K6RV]

I have been following this thread with interest because I too have a 
Centurion 422.  Mine is Serial # 03A10058.  Using Ten-Tec's code for 
Serial numbers:  Mine was built in March, Production Run 1, Unit 005, in 
1998.

One of the interesting things about this thread to me is that I had a 
problem a year or so ago with my Centurion with the same symptoms. Turns 
out the problem was NOT the transformer, but was a bad QSK Board 
(81542).  When the problem first occurred, I called Ten-Tec's Service Dept.,
(865) 453-7172, and talked to Gary Green, W4CJX, who is the Guru of all 
old things Ten-Tec.  He said immediately the problem was the QSK board 
which apparently is a common problem - they even have a "kit" of parts 
to send out to repair it.  I replaced the parts and problem solved.  You 
may find Bry, that when your new transformer comes back, you still have 
a problem, and if so, check the QSK Board.  If you read what the QSK 
board does, it provides voltage and switching for the control circuits.  
Not saying you did not diagnose correctly, but you may find an 
additional problem with that board.

My high voltage comes on instantly, by the way, as Bob said, with the 
Main on switch and not with the Standby/Operate switch

I cannot say enough for the guys at Ten-Tec Service - especially Gary, 
and the Manager, Paul Clinton - and how helpful they are on the phone.  
When ever I have had a problem with any of my Ten-Tec equipment, I have 
called them first, and 9 out of 10 times, they diagnose, and tell me 
what to fix or look for.  Example:  My OMNI V lost the display - it went 
dark.  I was in a sweat because the fluorescent display is not available 
anymore.  Called and talked to Gary, and he immediately said go over to 
the radio and pull out the display driver board plug slightly (it sits 
behind the display board and plugs into it).  I did, and, voila', the 
display worked perfectly.  Turns out the pins were made too long on the 
plug and when plugged in all the way, short out some of the tube display 
circuitry.  Unbelievable !  Without that phone call I would have chased 
my tail forever trying to find the problem.  My point is, whenever you 
have any problem with a Ten-Tec radio - call Service and ask for their help.

Good luck, Bry, with your Centurion.

73, Donald K6RV

> Message: 13 Date: Sun, 02 Feb 2014 22:31:58 -0500 From: "Bry Carling" 
> <bcarling at cfl.rr.com>
Thanks guys, It does appear that I was partly mistaken about how the 
soft start circuit works with the three relays. Power is indeed applied 
to the transformer whenever AC Power switch is turned on and the 
interlock is closed and the 12V is applied. I think this amp has some 
quite a complex circuits. it is a device that I had not studied at all 
before. Having so many interacting PC boards, I may have misunderstood 
the sequence at turn on for the two main switches. I hope that I have 
enough smarts left in me to figure this out carefully, and understand 
what is going on when the HV transformer gets back to me in a few weeks 
from Gary Brown. I will leave no stone unturned in checking all of the 
diodes, caps, transistors etc. before I start getting ready to apply any 
power. What I do know is that the 12V supply works, the filaments and 
pilot lamps light up when they should. HV Transformer had an intact 
secondary. One primary shorted. When the transformer gets back to me 
rewound, I plan to start it up on 120V at first, as one peson suggested 
and make sure I can get at least 800V or so of HT before proceeding 
further. Again huge thanks to everyone (including Robb) who has made 
efforts to guide me in this troubleshooting and repair. You guys' 
knowledge and experience are a huge help for somoene looking at this for 
the first time and pondering what the heck goes on in this wonderful box 
of tricks!

73 from AF4K Bry