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Jadis DA30: fuse keeps blowing

Since 8 months I own a 2nd hand Jadis integrated class A tube amplifier. It has worked fine until recently, when the left channel stopped playing, some 60 seconds after power-up. I opened the case, checked for any blown/ destroyed/ burned component, but the only thing blown was the left channel fuse. This I replaced and all was well again. Unfortunately, a few days later the left channel fuse blew again, within 60 seconds after power-up...

I have switched all the tube pairs (left pair to right and vice versa), but the left channel fuse keeps blowing, ruling out a faulty tube. Please note that after replacing the fuse, the amp is playing fine, but after some on/off cycles the fuse pops within a minute after power-up.

Has anyone experienced a similarly vague problem with a (Jadis) tube amp? What could be causing this?

Thanks for your assistance! Bernhard
dudok12

Showing 2 responses by dudok12

dudok12 OP
2 posts
 
The DA30 has been repaired by the Jadis importer in the Netherlands and now is well again. It turned out that the left output transformer was malfunctioning: when is was heating up, for some reason it started to pull more current than it should, causing the fuse (160mA fast) to blow after some 15 minutes...

I now have a new one and all is well again. Hope this helps, and good luck to Mattzack2!
dudok12 OP
2 posts
 
Thanks for your helpful comments! The DA30 is currently being serviced by the Jadis importer in the Netherlands...

@Polk431: The tubes were tested and were found to be OK: no shorts.

@Mcfarland: the DA30 is an autobias push-pull design. I swapped the left tubes (A+B) with the right tubes (C+D), but again the left channel fuse blew, ruling out that the left tubes were defective...

Will report back once the amp is working fine again!
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