I just bought a Line 6 212 combo amp with known problems.  Only paid $60 with the intent of using its case and Celestion speakers as a 2x12 cab for a small tube amp.  However, I want to be sure there's not an obvious, fixable issue with the amp before trashing it.  I now have the speakers plugged into a jack mounted on the inside of the cabinet....immediately reversible as needed.

The seller accurately described the problem and I verified yesterday.  When powered up, the amp goes through what appears to be its normal startup selftest. All the LEDs work when knobs are turned, and all appears to be normal.  From what I understand this is the most frequent issue with these amps.  However, when a plug is inserted into the guitar input the amp begins a loud buzz/hum that is not affected by volume controls.  Stops immediately when plug is pulled.  I have not removed the amp from the cabinet and will look for anything obvious when I do (like a shorted plug socket).  Is there any typical malady that causes this problem? 

From past posts on this amp, it appears that the computer side of the amp is what fails, so someone may want the amp section to do some parts swapping.

I'm not inclined to put more money in this since the cost of a session with a tech will put this amp at its market value pretty quickly, but I'd be foolish not to check it out.  In any case, getting a nice open back 2x12 cab with Celestions for sixty bucks is a very good deal.

Thanks for any comments.

Picked up the above amp at a yard sale this weekend ($30 which included a functioning Crate CR-19).  Both were filthy, but both marked "Made in USA"!  Couldn't resist. 

After cleaning the Peavy looks nice.  From what I can pick up from other searches, it's an older model with a 10 inch speaker.  When powered up the High Gain Input does not work, but the Low Gain does.  Volume and tone controls are scratchy, but that will clean up, I suspect.  Has very good volume and an impressive reverb.  I know I don't have a real treasure, but I would appreciate any insight as to how best to enjoy it.  I'm new to guitars (at age 63), but have become hooked on the technology.  This is my first over 15W amp so it's neat in that respect alone.

Thanks for any comments.