2. amps-preamps
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Parasound JC-1s Not Working

I just bought a pair of used JC-1s on Audiogon. The amps sounded fine until I was shuting down my preamp. My preamp is a tube linestage. While I was turning off the linestage, I heard some funny noise from both amps. Feeling uncomfortable about the noise, I turned the linestage back on. Surprisingly, the left channel amp did not work. The power was on but no signal.

I don't think it was the fuse. I swapped the external fuses between the two monoblocks. But it still did not work.

I wonder if this ever happens to you, JC-1s owners. Is there a switch or something inside the amp to reset? I flipped all the swithces on the back panel hoping that I could get the signal back. Still no use.

I am going to call Parasound on Monday. I know I won't have warranty since this is used. But before I call, do you folks have any suggestions? Thanks.
audiolui
audiolui OP
294 posts
 
Thank you all for your quick responses. I am going to open the amp and check out the internal fuses. External fuse is okay as I swapped them already. Will let everyone knows.
perfectionist
197 posts
 
Did you swap ic's to see if it is indeed an amp issue or preamp issue?
If not, you need to do this first.

There are two 12amp fuses on the mother board, you may have blown one or both. After you remove the top, you need to pull the fuse's and check them with a meter as they are ceramic and you can't tell if they're blown by looking at them.

And as stated, amps should be turned off first with pre's volume at zero and mute on.
jbm
58 posts
 
Turn the JC-l off, unplug the unit, remove the top. When you look down into the unit you will see some rail fuses. Replace the fuses with the same value. The unit should work fine. To repeat:: When using a Tube Preamp the turn on sequence is first turn on the Preamp and then the Amps. The turn off sequence is first turn off the Amps and then the Preamp.

One of my JC-1's died. When I replaced the rail fuses it worked fine. That was over two years ago and they continue to work just fine. I keep a supply of replacement fuses on hand just in case.

Good luck and good listening.
audiolui OP
294 posts
 
I visually check all the glass fuses (three on the rail and two on the motherboard right behind the back panel). They seem okay.

I removed the two glass fuses behind the back panel and also two ceramic ones right behind the transformer. I took these four fuses to Radio Shack and they tested with a meter so something. They told me all fuses were fine. Now I am really concerned. I will have to call Parasound Monday. Shoot. I am in a panic mode.

Now I understand the turn on and off sequence. Thanks for the tips.
johnjbarlow's avatar
johnjbarlow
175 posts
 
Don't freakout too much. We all have made a mistake or two in this hifi life of ours. I have been lucky because I have hifi friends nearby that can loan me gear if necessary.
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