Hi all...
Turned on the 70 yesterday, and about 30-40
secs in, there was a blue flash and a pop thru
the spkrs.. well more like a "POfffT" than pop.
After that, it seemed fine, by the looks of it anyway.
I hesitated for a moment, wondering if it was a
passing phenomena and since nothing else bad
seemed to be happening, then thought the better
of it and switched off.
Didn't try listening, as I figured damage might be
caused and better to just switch off and figure out
what happened.
I WAS looking at it when it happened, and yet
couldn't tell exactly where it came from...
except that it *seemed* to be in the vicinity
of one EL34 pair.
Only other sign... and I'm not certain of it, is that
the 5AR4 seemed to maybe be a bit brighter
glowing than usual, but I could be wrong.
Some background info:
The amp is a total rebuild completed this past
May (thanks to help from the great folks at diytube!)
After putting around 300 hrs on it with heavy daily
use for "break-in", its been used almost exclusively
on sundays all day, since then.
Its been working great, making beautiful music
since then with no sign of trouble, including
the previous evening.
*I haven't adjusted bias since then*, after the
initial checks/adjustments in that initial period.
The amp consists of the following:
Tubes = JJ e34l and 5AR4, JAN-Phillips 7199s.
PC board is a modern replica PC3.
Can cap is the 40-> 80-> 30-> 20 from Dynakitparts.
CL-90 added.
Everything is new save for chassis and iron.
Plz let me know if other details would be helpful.
Any thoughts?
Thanks in advance.