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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
hifihvn
943 posts
 
Emission testers don't give the results as good as a good mutual conductance tester. Some miss some of sections of a tube. But a good mutual test can too at times. Test the other tubes first just in case one of them let go. It sure can save the trouble. One may have let go, do to the different voltages in the preamp, from the new tube drawing more current if it is, or is not shorted. Odd things happen.
detredwings
162 posts
 
Since you have no sound from both channels? I would think your problem is with the power supply. Same supply for both left and right channels. If you have a phono section it also has one for it. If your tubes all light-up, then I would bet your B+ went out. Probably one of the regulators. I think you will need to send it to a shop. They are not difficult to work on.
hifihvn
943 posts
 
Detredwings, the odds are probably something else probably did give out, but I'm thinking of anything to try (he has a tester that may show a dead tube), that may be a simple home fix. Some info on the net may be wrong (a PV10 showed a PV3? schematic), but it may share a 5751, used for both channels. What CJ is partially showing (tube sockets) , and a schematic on the net doesn't match. And CJ inverts polarity, usually meaning one less tube in the path a lot of the time. Just a last free shot, I'm thinking.
detredwings
162 posts
 
I thought power supply because it said he replaced the original tubes and still no sound. But hey I've been wrong more than once before. I had a PV12 before and it had a regulator go bad and it caused a problem much like he mentioned. Anyway let us know when you get it solved.
hifihvn
943 posts
 
I'm guessing there's a possibility that moving around in there and bumping another tube, and the tiny wire in the tube that feeds B+ inside one other tube that feeds both channels, half left, half right (5751?), could have let go. Not the filament, because he would see that. I've seen plenty of odd things happen. Just like the new tube that may be shorted, probably happened during shipping or handling. Just a long shot. It is a bummer.
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