[Johnson] Invader 2000 fuse blows

[George]

Hi all,

Before I end up with no hair left (from pulling it out one at a time) I
could use some help.

I have an Invader 2000 that blows the low voltage fuse.  With the high
voltage supply disconnected and the transmitter in standby, the fuse will
blow after about 10 minutes of warmup.  I had a standard 5R4 in the power
supply and it would arc over just before the fuse blew.  I changed the 5R4
to a military grade and it no longer arcs but the fuse still blows.

If I remove the 5R4 the fuse doesn't blow.  If I remove the 5U4 and leave
the 5R4 in, the fuse doesn't blow.  With both tubes in, it blows.

Any suggestions?

Thanks

George, NY2O