[TenTec] Centurion Amp. Problem

Bry Carling bcarling at cfl.rr.com
Tue Feb 4 09:20:42 EST 2014

Did you ever figure out what it is on the QSK board that was blowing the 20 A fuses?

Best regards - Bry Carling

> On Feb 3, 2014, at 9:18 PM, "Donald, K6RV" <K6RV at earthlink.net> wrote:
> 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
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