Jc 120 has issues

[Gundecker]

New to the site, I looked at Jc 120 threads but I did not see anything related to my problem. I love this amp but it is breaking my heart by having something different wrong with it every time I move it.
Sometimes it crackles with a loud low pitch static,very random and intermittent.I move it to another room or gig space and it works great for a bit then one speaker or side of the 2nd channel only has about half normal output. Move it again, buzzes when my guitar gets near it. Last move has channel 2 with only half the volume of ch.1 and left speaker weak. I swap speaker leads and right speaker is weak so I know it is half of ch.2. Ch.1 works fine. Ive had it apart and checked for obvious loose connections,etc.
Any ideas? Tech time?

[J M Fahey]

Well, nothing strange, your amp simply is OLD and obviously has travelled a lot.
Let´s go step by step, but tomorrow, because it´s 01:30 AM here and I´m too sleepy and tired.
Good luck.

[Gundecker]

Well my amp has an unknown history as I bought it at a Music -go-'Round years ago and it was cheap because it had problems but they didn't know the nature of them.The two high input jacks are broke and my main issue with it is the ch.2 left speaker(or right depending on the hook up) being weak. It takes away from the stereo chorus sound and overall performance. This would be my first fix.

[phatt]

Hi Gundecker,
At the Age you may have failing Capacitors and add some cracked solder joins,,
(both are often not easy to see for the untrained)

Wait till Mr Fahey wakes he might have some clues where to look first.
Even the best brains need sleep time :lmao:

Mean time get a magnifying glass and check for cracks in the solder joins.

Those big cylindrical Electrolytic capacitors often get mechanical movement and the solder joins develop hair line cracks which can only be seen with magnification and strong light.

Of course there maybe other deeper problems but check the obvious ones before looking for design flaws in the universe.  :duh

Someone once stated that 90% of electrical problems arise from from connections and I tend to agree.
The Devices themselves don't fail that often.

Any intermittent issues can usually be a sign of connections failing. 8|
Phil.