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blowin' fuses (Gibson GA-8T cont.)

7/2/2000 8:02 PM
Sean Kilback
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blowin' fuses (Gibson GA-8T cont.)
Still working on my '64 Gibson GA-8T...  
 
It blows fuses when turned on if all tubes are in the amp. When ALL tubes are removed (including rectifier) the the fuse is fine, and the voltages look ok, even on the heater winding. Of course, with the rectifier removed the rest of the circuit is not seeing any voltage...  
 
Using RG Keen's tube amp debugging page (big thanks RG!), the PT looks ok. Next, I checked the OT and the secondary windings are shorted to the chassis. The primary windings look ok (162R and 141R which is within the 1K tolerance RG suggests).  
 
My question is this: will shorted OT secondary windings cause the fuse to blow? Since the tranny is supposed to block DC I can't see why this would happen. Perhaps I have to look elsewhere (as well as replace the OT).  
 
Again, thanks for any help you can think ok!  
Sean

 
Replies:
Sean Kilback Of course, that should have have re... -- 7/2/2000 8:03 PM