On my VTA ST-70, recently noticed upon start up a bright white arc, which happens twice on the base of the rectifier tube, then does not reappear. They last for a millisecond roughly 30 seconds apart. Run the amp for several hours and does not reappear at all. Have installed the yellow sheet mod a few years ago. Do use a variac set at 118VAC. Anyone else have this happen? Thoughts?
2 posters
Bright white Arc
Brap- Posts : 231
Join date : 2013-11-28
Age : 68
Location : Plainfield, illinois
peterh- Posts : 1833
Join date : 2012-12-25
Location : gothenburg, sweden
Seen that, time to get a new GZ34 . And do check bias at the same time.Brap wrote:On my VTA ST-70, recently noticed upon start up a bright white arc, which happens twice on the base of the rectifier tube, then does not reappear. They last for a millisecond roughly 30 seconds apart. Run the amp for several hours and does not reappear at all. Have installed the yellow sheet mod a few years ago. Do use a variac set at 118VAC. Anyone else have this happen? Thoughts?
Brap- Posts : 231
Join date : 2013-11-28
Age : 68
Location : Plainfield, illinois
Thanks. found in my "stash" a NIB Sovtek 5AR4. Minor tweak to bias and reset to .450 - .455. All good, no arc.
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