JVC A-10X stereo amp - crackle and noise in left channel

Bram9206

New Member
Hi,
I have here a 1980 JVC A-10X integrated stereo amplifier. Not the best, I know... but still I would like to fix it. Here is the problem:
there is a lot of loud noise and crackle in the left channel with speakers hooked up. Even when there is no source selected and the volume knob is at 0. The noise occures in the left channel with "speakers 1" as well as with "speakers 2".

I already checked all pots and knobs, as well as the speaker terminals, but no problem there. I also did the chopstick test on most components in the left channel, but it's hard to make something out of that since the crackle/noise is too irregular, too uneven...

And then there is this problem that I don't have the service manual...
Is there anyone who has the service manual of that JVC A-10X?
And is anyone familiar with this rather general problem?

Thanks a lot guys!
 
Service manual

There's one listed on the auction site now.

Sorry I can't help regarding the noise issue.
JVC makes very good components and it's definitely worth fixing.

Glenn
 
Anyone any idea? This is a rather general problem, so I was hoping someone had the same problem with this or another stereo amp who could help me out?

Maybe Mark The Fixer has any thoughts on this?

Thanks a lot.
 
Does the bottom of the case come off? If so, remove it and inspect the solder joints, particularly on the larger components.
 
That is a bit the problem with this JVC gear... It doesn't have a bottom panel that comes off easily... I already examined the thing and it would take me some time to get to the other side of the PCB... But I will eventually.

Someone told me it could be a faulty driver or pre driver transistor. Anyone knows how to recognise them? The main problem is that I don't have the service manual... that would make things a lot easier... Anyone has a pdf?
 
This is what I have now: I re-soldered all transistors in the left channel and the crackling got much more silent, if not away. Still there was some noise... I found out the PCB is attached to the chassis with two screws in a way that these screws also function as a ground. One of the two screws was kind of rusty and when I tapped it I could clearly hear this was causing the remaining noise! So I cleaned the whole thing with a fine file and used a new screw so it would ground again and guess what: the amp is super silent now!

So, by re-soldering all transistors I probably fixed a dry solder joint (I was not aware of) and I cleaned a ground issue and all the crackling and noise is now gone. The amp is really dead silent now and music is playing perfectly.
 
Congratulations! This is a very common problem. Manufacturers use the screws to complete the ground path through a receiver or amp. Sometimes it is the screws that hold the PCB down, but sometimes it is one of the screws on the input jacks on the back panel. You learned something new today!:banana:
 
Good news!
Also as I said earlier, you can download the service manuals from several sites.
Just Google it. Sometimes you'll find a free download.

JVC Super A amps are very good sounding amps.

Glenn
 
Thanks for the support guys.

I googled several times to find a free download of the service manual, but haven't found one... I find a lot of pdf's that cost like $18 or so... Let me know if there is anyone out there with free pdf of the service manual. Could be useful for the future!

My very best,
Bram
 
I had the same problem with AX1100, and of course it was a bad solder joint,
search around the volume pot, mine has a Gm circuit attached to volume pot, with a lot of components, and the bad joint was there..
 
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