Have you tried putting the old tubes back in to see if it works? Assuming they were still working in the first place.
If that allows it to work the problem was a tube only, then it is a matter of finding out which one, which is basically a process of elimination.
Try that first. |
Yes, I put the old tubes back in. I also replaced the fuse. No sound. A bit of a pop and hum after about 20 seconds (when it would normally come on, then total silence). |
Sounds like you had a faulty tube that took out a resistor or diode. Probably need to send it back to cj for service. Bummer...sorry. |
What's really frustrating is that I recently bought an emissions tube tester, and it showed the tube to be good (with no shorts). So much for that... |
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. |
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. |
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. |
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. |
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. |
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. |
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. |
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. |
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. |
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. |
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. |
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... |
