[TenTec] 9420 PS Problem

[Rick W]

Well this must be my month for power supplies.  I just finished fixing my 32 amp Alinco switching supply and today another PS problem.  

This morning I turned on the rig to work a new one and hit the switch on the Hercules II.  Nothing happened!  No lights -- nothing.  I checked the line fuses to the 9420 and they were fine.  I checked the internal fuse on the Herc and it too was fine.  

I decided it must be the 9420 so I dug into it (damn this thing is heavy).  Well would you believe there is a fuse on the power supply controller board.  I thought that MUST be the problem.  Unfortunately it too was good.

After some more digging I found that T5 on the controller board (Figure 4-5 of the manual) was dead.  Both 110 VAC primaries were open.  (I run 220 VAC and these windings are in series). This transformer feeds a  couple of diodes, a filter and a 7815 regulator.  It provides the +REG voltage and turn on voltage for the controller relays. I am still a little concerned that BOTH primaries failed.  

I removed the transformer and applied 18 VDC to the 7815.  When I turned on the Herc it came to life.  

Unfortunately there are no specs on the transformer in the manual and no markings on the item itself.  Would anyone on the reflector have any ideas of what might make a decent replacement.  (I will give TEN-TEC  a call on Monday.)

My plan is to use my variable power supply to apply a voltage to the regulator until a replacement transformer can be found. 

Thoughts or comments welcome.
 
73,
Rick
VE7TK

Website: http://www.ve7tk.com