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It Just Stopped



Original poster: Mddeming-at-aol-dot-com 

Hi All,
     Something happened last night that has me puzzled. I was testing 4.25" 
coil. It had been run intermittently for about 1/2 hour. I fastened a 
pointed rod to the center bolt of the topload (dual toroids) pointing 
upward, preparatory to making a "pinwheel". I was getting nice 3ft+ arcs to 
the ceiling of the lab, (coil is caged 10' x 9' x 8'.) After about a 
minute, it suddenly went dead. No arcs, no gap spark, no sound except the 
vacuum on the sucker gap. It had been drawing ~18 Amps on 30 Amp circuit 
prior to problem. Indicator lights showed power reaching primaries of NSTs. 
Variac output showed 120V. No racing sparks noted, no arcing to primary. I 
shut system down, waited ten minutes, tried to restart... Nada!
     I disassembled everything and checked each component:

Xfmr 1 Allanson 15/60:  6000v left and 5990v right to ground terminal with 
102V input. (My HV meter limit is 6 kV)
Xfmr 2 Transco 15/60: 5995v left and 5980v right to ground terminal with 
101.8v input.
Tank cap: Maxwell 37xxx series, 30 nF nominal,. measured 29.95nF with RdShk 
DMM and 30.91 on AADE L/C II-B. On the 14th of July, it measured 31.07nF on 
the L/C II-B when air Temp was 11F warmer and Humidity was 30% higher.
Sucker Gap 1 HP vacuum spaced 7.5 mm.
Safety Gap spaced 5 mm Left and 4 mm Right.

     Reassembled everything and... Nada!!

Any Guesses??

Matt D.