joch230 Posted June 29, 2010 Share Posted June 29, 2010 I meant to replace the stock 12AX7 tube with a 12AY7 in a almost new Valve Jr amp. By mistake, I took out the EL84 tube and put it in the new 12AY7 slot. Of course, it didn't work. I then put the EL84 tube back where is was supposed to go. Everything is light up but I don't get any sound out. I obviously toasted something. Maybe I toasted the stock 12AX7 tube? A fuse? (the only fuse I see is one on a orange wire that is like shrink wrapped in a black plastic....goofy design). Any thoughts or ideas greatly appreciated. John Link to comment Share on other sites More sharing options...
Old_Ampeg_Guy Posted June 29, 2010 Share Posted June 29, 2010 John, take it to an amp repairman. If you haven't worked on tube amps before, you could get enough voltage from the caps (capacitors) to kill you, even after the amp has been unplugged and sitting that way for a while. It's not the answer you were looking for, probably, but it's worth noting. Welcome to the forum, by the way! OAG Link to comment Share on other sites More sharing options...
fuse Posted June 29, 2010 Share Posted June 29, 2010 Your message is confusing regarding what tube went where. If you were replacing the AXY, why would you remove the power tube. And, if you removed the power tube and out it in the preamp slot, that means you removed one of the pre tubes and the power tube. What did you put in the power tube slot? The bottom line is.... check the fuse with a meter or put in a new fuse, put everything back the way it should be and start replacing the original tubes with a new tube. It will not take long to find out if it is more than a tube you burned up. Link to comment Share on other sites More sharing options...
joch230 Posted June 29, 2010 Author Share Posted June 29, 2010 Bill....the amp only has two tubes. EL84 power output tube and the 12AX7 tube that I wanted to replace with a 12AY7. Well, the 12AX7 has a metal spring loaded cover...I know that now but didn't know that to start. Not seeing the covered tube, I replaced the only tube I did saw. Believe me, I will never do that again! The fuse doesn't have a standard tube holder....it's really tacky. It's like it's taped/plastic wrapped to the wire. Poor design. Most likely will have to bring it in to see if I blew a resistor or something. Link to comment Share on other sites More sharing options...
RSDx Posted June 29, 2010 Share Posted June 29, 2010 The fuse doesn't have a standard tube holder....it's really tacky. It's like it's taped/plastic wrapped to the wire. Poor design. [confused] Did you buy this amp used? I have 2 VJrs - an old version 1 combo, and a version 3 head'n'cab - both have regular in-line fuse holders.....sounds as though someone butchered yours previously, perhaps ??? Link to comment Share on other sites More sharing options...
fuse Posted June 29, 2010 Share Posted June 29, 2010 [confused] Did you buy this amp used? I have 2 VJrs - an old version 1 combo' date=' and a version 3 head'n'cab - both have regular in-line fuse holders.....sounds as though someone butchered yours previously, perhaps ???[/quote']RSD is right. This sounds funny......At any rate, did you change or check the fuse? Can you post some pics.....? I am not a tech, but I am thinking the most likely scenario at this point is a blown fuse and the pre tube you installed is toast. I am kind of thinking the amp is fine. Maybe a burned up cat resistor or cap, maybe the grid resistor got cooked.......you would need to open the amp. But replace that fuse first. Good Luck Link to comment Share on other sites More sharing options...
joch230 Posted June 30, 2010 Author Share Posted June 30, 2010 The fuse is actually soldered in. Stupid design. But the whole thing lights up, on switch and tubes so it wouldn't be the fuse. Going to take it to an amp tech. I bought this from Musicians friend....new around Christmas so it's not old at all. Thanks. I'll let you know more when I find out more. Link to comment Share on other sites More sharing options...
Dave Posted July 6, 2010 Share Posted July 6, 2010 I may be way off here, but doesn't the EL84 have a large socket like the 6L6? I know the 12ax7 is a small wire pin socket and the 12ax7 wouldn't even fit into the power tube socket, at least not correctly. Link to comment Share on other sites More sharing options...
fuse Posted July 6, 2010 Share Posted July 6, 2010 I may be way off here' date=' but doesn't the EL84 have a large socket like the 6L6? I know the 12ax7 is a small wire pin socket and the 12ax7 wouldn't even fit into the power tube socket, at least not correctly.[/quote'] The 84 is a Nine Pine socket, just like the AX7. If you are unfamiliar with amps, and the tube retainer is missing from the 84 socket; it would be easy to mistake the 84 socket for that of an AX7..... Link to comment Share on other sites More sharing options...
joch230 Posted July 6, 2010 Author Share Posted July 6, 2010 My Father-in-law is a semi-retired TV-Stereo repairman. He said just bring over the schematic and he would check it out. He has a home shop as well. Link to comment Share on other sites More sharing options...
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