2204 high input not working... weird

[Julesman64]

So I just got my hands on an '83 2204 (by just i mean like yesterday), saw it up at a mom and pop music store and had to have it. Checked it out at the store and all seemed good (never got to crank it up to see what it could really do) just some scratchy pots that I was able to work clean again. :dance

So this morning I woke up and started giving it a little cleaning, it was quite dusty. Thats when I noticed it was loaded up with ECC81's and not ECC83's. No biggee, I got lots kicking around. So I popped 3 old 12AX7's from my VM in there. But now the high sensitivity input does not work. As soon as I plug into it (even while on standby...) all I get is a loud buzz, so I'm wondering if perhaps one of those ECC83's aren't working, or if something has decided to give out on me. Both inputs were working at the store yesterday. I'm going to fiddle with some other tubes right now, but if anyone has any input that would be appreciated!

[surfnorthwest]

It could be many things, doesn't sound like a major issue though. With any older used amp it is always a good idea to let a tech go through it to correct any issue and give it a good bias. The 2204 is a keeper and if you plan to keep it long term just go have it serviced.

[Julesman64]

Its all good, I just swapped out the preamp tubes and now all is well. I did some more cleaning with some compressed air and Deoxit. She's all roses now :party

[ironlung40]

Its all good, I just swapped out the preamp tubes and now all is well. I did some more cleaning with some compressed air and Deoxit. She's all roses now :party

contact cleaner with lubricate is your friend, friend. You can spray some on the bottom of the preamp or output tubes, or even a little into the sockets, then work the tubes in and out a couple of times. This will clean the sockets. Sometimes, this helps a dusty amp that seems to have a bad tube, when in fact, it is just not getting a good connection.