Conrad Johnson Premier 140 fuse is blown


Hi Audiogoner.
I need your advise on what I should do now.
This morning, my amplifier’s fuse has blown on the left side while listening to music. 
Should I change the fuse and power it back on or should the amp be checked up by a technician?
 Thanks for the advise if any. I have no knowledge on electronics.
Calvin
dangcaonguyen
Put a cheap fuse in and retry, worst to happen is it will blow it again, then call the tech.
Change the fuse and see what happens. The fuse is there to protect the unit. If it blows again, the amp won't be damaged but you should then get it checked out.
Straight from the CJ Premier 140 manual:

What happens when the fuse blows? If one of these fuses should blow, it usually indicates a marginal output tube (one of four for each channel odd numbered tubes for the right channel, even numbered tubes for the left channel) and an attempt should be made to identify and replace it, by either (a) replacing the fuse and turning on the amp while watching the output tubes carefully; look for a bright white or blue flash inside the tube. If nothing happens, then (b) lightly tap the output tubes one by one with the plastic handle of a screwdriver while watching for flashes inside the tube. If efforts to identify the bad tube fail, the best course of action is to replace both tubes in the channel that blew the fuse. If the tubes are over two years old, or have more than 1,500 hours on them, a complete replacement tube set is probably in order.

Thank you all.
I will order a set of tubes and the fuse. Hopefully everything will be fine after those replacements.
Calvin
If it was a fault in the fuse.

You must check at least with a meter or any signs of damaged components, likely resistors or whether any tube is bad.

Likely, a tube or more has shorted. This takes out some other components around the faulty tube and this short will take out the fuse.

There is only a very small chance it will work by just replacement, lest the time the new fuse blown again,  can take out more components.
Make sure that the speaker connection did not come loose. That will also blow a fuse!
What kind of fuse ? Please remember a stock steel bus fuse can vary up to 
15% in value , precision fuses like Hifi tuning Supreme  Synergistic are within 
1%  and can blow quicker, it happened to me several  times ,I go one small step up in size with a premium fuse still plenty of protection 
like from a 3 amp fast  to a 3,125  fast blow.
Follow the advice in the manual, provided by the equipment manufacturer(as mentioned above).      
Hello all,
After the replacement of 8 KT-88 Reissued Gold Lions which I purchased from Upscale Audio and the KTK-1 fuse, my Conrad Johnson Premier 140 is working as normal. 
Thank you all who have sent suggestions to help me. 
Calvin
Hello again.
my amp is working as normal. The sound come out beautifully with no distortion in both channels. 
BUT,
when I look at the amp from the front, there is one tube out of eight total glow brighter than others. I checked the old tube in that position, and figured out that old tube was bad, I can see the smokes deposited on the glass. 
Is it just a coincidence or do I need to bring the amp to see the tech?
Thanks
Calvin
Never mind.
I switched tubes and the bright glow tube followed to the new position. 
Should I contact Upscale Audio to exchange the tube?
 Thanks 
From indications; that would be a good/safe idea. Did you carefully follow the manual’s re-biasing procedure, for each tube, repeating it after 30 minutes? That should have also been performed, after the glowing tube was moved.
Upscale should agree, you’ve done your due diligence.  Kevin does(typically) take very good care of his customers.
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