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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
 
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.
countryjazz2 OP
17 posts
 
I tried switching out the tubes. I'm getting a pop when the preamp would usually kick in (similar to the one you get if you shut the preamp off while the amp is still on? All the tubes test OK, including the ones that I put in that appeared to blow it out.
mofimadness's avatar
mofimadness
4,982 posts
 
If you are getting a "pop" instead of a "click", that might be the mute relay. When you turn the preamp on, the mute relay stays on for the first 30 seconds or so to stabilize the electronics and tubes. Then it clicks off to allow the signal to flow through.

I was a cj dealer back in day and we had alot of problems with faulty mute relays. I'm not sure how old your preamp is, but I'd give a call the cj tech support and see what they have to say.
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