DLite blown fuse Question

[lite1]

Just hoping for some input from any knowledgeable sources out there. I just finished up my Dlite build with 6L6's. I had an initial problem when I first powered up which turned out to be a heater jumper bad connection but power remained on-no blown fuse. I then installed all tubes, hit main -ok, then standby-boom fuse was baked. I then checked all voltages without tubes-everything good. Next, installed 12AX7's, all voltages good -no blown fuse. With the 12AX7's in place I installed 6L6's-blown fuse again. Now I'm using fast acting fuses, could it be that simple? I even had the 6L6's tube tested although I believe the testing voltage is around 100v, could a bad 6L6 possibly be the culprit?
thanks for any suggestions

[Structo]

Did you do your first power up with a light bulb limiter?
Without tubes first then with tubes?
Check your wiring to the power tubes and your power transformer wiring.

[lite1]

all done, and was able to determine the heater jumper issue. Can you tell me what type of fuse you're using-slow blo or fast acting? and does it make a difference?

[heisthl]

SLO-BLO is best - but it still shouldn't blow fuses unless your running the power switch on and off like a strobe light. Assuming you've checked that your bias supply doesn't have tha cap reversed (+ terminal should go to ground), Remove the output tubes and if the "bulb" is still bright (meaning you still have a problem) remove the other tubes and see if it makes any difference, if no, while still on the bulb and with standby in operate is there porportionally correct voltages down the dropping string? If no - disconnect from power and use the OHM function on your meter at the filter caps - if any of the + cap terminal measures 0 ohms to ground (short) you have a bad filter cap. If that's all good disconnect the resistor between B+2 and B+3 to make sure it's not something down the line drawing too much current, and narrowing your problem to just the main output stage. The fact that it works in standby mode means your problem is not heaters or relay supply and most likely not the bias supply.