2. amps-preamps
  3. 1232055231

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
footsurg
25 posts
 
More than likey a low value shorted cap or resistor in the power supply that is causing a slight overcurrent situation on the left channel causing the fuse to blow but not immediately. Sounds like your unit is going to need a lookover by the Jadis people. Find the nearest service center and send her in.
polk432
1,142 posts
 
I had the same problem with a Cary V12R amp. One tube did have a short and 2 more read replace on a tube tester. I now have a new set and no problems. One thing I used to do was to take out the fuse that was blowing before turning on the amp and put it back in, then turn the amp on, and the fuse worked fine. Hope it works for you, but I'd have those tubes tested on a tester. Also check the bias on your amp if it is not automatically adjusted. Good luck.
loki1957's avatar
loki1957
122 posts
 
Check the tubes first. If the tube is bad it will blow the fuse to protect the speakers.If that doesn't help call Pierre Gabriel. He doesn't return calls or emails easily but stay on him.
mcfarland
356 posts
 
I am not sure that you can just "swap tubes around", and, now knowing that you've done just that, have you checked the bias voltages recently?
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!
More to discover