[TenTec] Centurion Problem

[Michael Marx]

Hi Guys,

I have a Centurion that experienced some kind of arcing event which resulted in one of the traces on the Filter/Rectifier board that connects to the secondary of the transformer to actually vaporize.   I bridged the trace, replaced the capacitors and checked the diodes.  After repairing / rebuilding the board, I reinstalled it and now have normal B plus.  HOWEVER, I have 200 mA of standby plate current.  This suggests the bias transistor is blown and I have had this problem in the past.  Unfortunately, I replaced the bias transistor and still have 200 mA of standby plate current.  My question is:  Do any of you have an any idea of what to check besides the bias transistor.  Or, is there some common cause for the transistor to fail?  I bought 5 of them from Mouser and hesitate to keep replacing them until I know what is causing the failure.  The transistors I bought are IDENTICAL to the transistor I bought from Ten Tec the last time it failed.  

thanks
73
Mike WB0SND

Michael Marx
sndtubes at vacuumtubes.com
636-939-9190

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105 N. Division St.
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