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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
12 responses Add your response
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!
mattzack2's avatar
mattzack2
175 posts
 
I have the exact same problem on an Jadis Orchestra Reference. I also replaced the left channel internal fuse, which again blew in just a couple of minutes. I rearranged KT88 tubes from ABCD to CDAB. Fuse did not blow, but bias was way off and sound was horrible. I tried to rebias the tubes but the 120 mV DC was floating up over 200 mV as it warmed up. I have several calls into Pierre Gabriel with no response, and also tried Jadis France. They told me that Pierre was moving locations but would be in touch soon. Right now system is completely down. Please contact me or make your solution public in the Audiogon discussions. Thanks - Matt
missioncoonery
1,223 posts
 
If your within sticking distance contact Brooks Berdan in Monrovia CA and dont mess around with distributors..Brooks is authorized Jadis since day one it seems and his bench tech is spot on with Jadis gear(they have all Jadis parts as well, which really makes a difference)..good luck
mattzack2's avatar
mattzack2
175 posts
 
Dudok -

Did you resolve your fuse problem? My Orchestra is still in the shop. Tech found one of the Jadis KT88's shorted. I bought a matched quad of Gold Lions and had them installed and biased. Got it home and the KT88's started glowing red when I cranked it up, the sound quality was terrible, and finally blew the external fuse. I brought it back to tech, swapped tubes, and as of today, they are feeding a square wave into it and seeing a lot of distortion. Did Jadis offer you any suggestions?
Matt
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!
mattzack2's avatar
mattzack2
175 posts
 
I still have not heard from Pierre Gabriel after about a dozen phone calls and emails. I am very surprised and very disillusioned about Jadis support.
I am trying to get a recommendation for a Jadis service tech in the Chicago area. I did get a fine recommendation for a Jadis service tech in California, but I am hoping to find someone local.
trelja
3,223 posts
 
I could fix your DA30, and can do it at low cost.

However, if it needs a new output transformer, I'm not sure how we would go about sourcing one, as Pierre Gabriel may need to be involved due to it needing to come directly from Jadis.
missioncoonery
1,223 posts
 
Pierre Gabriel wont respond to your service request..I tried for over 2 years and never got anywhere...Jadis has a very poor customer service..
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