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Tube fuses on Jadis JA200 amps

Is there anyone that owns these amps that can tell me why the tube fuses blow. Does it mean the tube is bad? I retubed a little over a year ago and all of a sudden I've lost 3 fuses. I got 3 to 4 years out the last set(SED EL 34).I know the fuse filaments are microscopic. If I just replace the fuse it will hold for a while and then blow again. If I put a different tube in then the fuse holds. I know it sounds like I just answered my question but does someone have an explanation for me. Could it be power line surges?
128x128loki1957
rcprince
3,070 posts
 
It is the tube starting to go bad, though you should keep the tube in there to make sure it's not a one-time thing (unless the tube is glowing cherry red, then it's a goner). One year is about all I got out of any 6550s or EL34s in my JA80s before the fuses started to go, and that's what I'd expect out of the 200s as well; the only tubes that lasted longer (3 years and still going strong when I sold the amps) were the Gold Lion/GEC KT88s. Whatever you do, make sure you use fast-blow fuses; slo-blows will take out some resistors and give you that nice burning smell when they go.
ampnut
7 posts
 
Dont forget to change the tubes as a SET,

Changing only 1 tube, will mate yr new tube, with labouring old tubes... killing the new tube Fast :-(
eytan1111
1 posts
 
What does it mean to "change the tube as a single ended triode"? I have JA80s with the same one to two fuses blowing on single chasis with new el34 and 6550. Overall sound quality and volume is down even when placing new fast blow fuse...help! Many thanks,
42659
77 posts
 
Strange your fuses go out so quickly. I had a Jadis defy 7 amp for 3 years with no fuse problems using Sev 6550 tubes. My current Cat JL2 amp which I have owned for 5 years requires tube replacement about every 3 years using Sev 6550.

I would suspect a bad tube or two or perhaps a faulty resitor in your amp. Troubleshooting with so many tubes and resistors can take much effort to isolate.

Johnny
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