2. analog
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CJ PV-10 no sound

I installed a couple of GE 12AT7WA's (bp triple mica, aquired on E-Bay)into my CJ PV-10 today, and as soon as it came on, snapping sound and a hum. Now, no sound coming from pre-amp. It appeard as if one of the tubes shined brighter than it ought to prior to this happening. I'm going to go and get a new fuse to rule that out, but it looks OK. (BTW, so much for a the tube tester. Tested very good, no shorts!). On a seperate note, if I'm not able to get it fixed right away, I've tried running my NAK 670zx directly to my Classe 15 amp, and running my X-Ray CD player through the cassette deck. Sounds great (although I ALWAYS miss my tube sound). Any problem with this? Thanks
countryjazz2
orpheus10
8,668 posts
 
If you have a shorted capacitor some where, it will blow the tube each time it's replaced. That can get expensive. I think you should send it back to CJ.
countryjazz2 OP
17 posts
 
It sounds a little like when you accidentally shut the pre-amp off when the amp is still on, but not as bad. No sound in the speakers whatsoever after that.
microstrip
180 posts
 
I would also suggest a power supply fault - the PV10 has a series pass HV regulator using an MJ340 , a MPSU10 and a MPSU60 transistors. Most probably the fault will be in first two transistors - the third one is just a current source to bias the zener diodes used as regulators.

As they are inexpensive I would risk replacing them if there is no HV at all at some parts of the tube sockets.

I have owned several cj preamplfiers and amplifiers for a long time and the few problems caused by defective tube problems were always solved replacing just these three transistors.
countryjazz2 OP
17 posts
 
I don't know how to do any of that, and there is no hi-fi shop in my area. Hopefully I can find someone to go over it for a reasonable price. Thanks.
countryjazz2 OP
17 posts
 
Thanks to Gary G., I'm sending it up to Tom in North Florida. He seems like a great guy, and really knows his stuff. Maybe I'll get a few good mods done to boot. Thanks for the all the feedback...
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