Members nuke_diver Posted October 28, 2008 Members Share Posted October 28, 2008 I got some 12AU7s for my Crate V18. Simple matter to swap out the AX7 for the AU7 in V3 right. I've already done a complete tube change without incident. I swap out the one tube...nothing..no sound . I check the contact seems good still nothing. I think maybe a bad tube I put the old one back in...Still Nothing Any ideas I think my 45 day return period just end, if I broke it I own it Link to comment Share on other sites More sharing options...
Members NOS68 Posted October 28, 2008 Members Share Posted October 28, 2008 Did you check the fuse? Link to comment Share on other sites More sharing options...
Members nuke_diver Posted October 28, 2008 Author Members Share Posted October 28, 2008 There is some sound...just very low and scratch with the volume and gain dimed...should have mentioned that. I think if a fuse is gone there would be none? Checked the fuses they are fine Link to comment Share on other sites More sharing options...
Members richey888 Posted October 28, 2008 Members Share Posted October 28, 2008 Try putting the old tubes back in......I'm sure you know this, but check the speaker connect, it can come loose when you flip the control panel back. Good Luck and let us know how it comes out.....mojo to ya bro! Link to comment Share on other sites More sharing options...
Members pekelnik Posted October 28, 2008 Members Share Posted October 28, 2008 Try putting the old tubes back in......I'm sure you know this, but check the speaker connect, it can come loose when you flip the control panel back. Good Luck and let us know how it comes out.....mojo to ya bro! He put the tube back in and it's not going to be the speaker contact if he has some sound.. Try pushing the socket that you took the tube out of around? There could be a bad solder somewhere around there. Link to comment Share on other sites More sharing options...
Members Ryan Trevisol Posted October 28, 2008 Members Share Posted October 28, 2008 12AU7 and 12AX7 are two varieties of the same tube design. Swapping them should be just as simple as that. As long as you put the tube in correctly, didn't force it, and didn't line up the pins wrong, you should have been fine. I'm inclined to agree with pekelnik, sounds like something might've gone wrong with the socket, especially if it's PCB mounted. Link to comment Share on other sites More sharing options...
Members nuke_diver Posted October 28, 2008 Author Members Share Posted October 28, 2008 Yeah Richey I tried the old tube thinking the AU7 was bad but same problem. Previously when it worked ok I always noticed a slight pop sound when switch from standby to on. Now I don't hear that. I looked at the based of the PCB where the socket is mounted but I don't see anything obvious. I could try resoldering it (had to do that with my wife's car to fix a cold solder issue with the dashboard) but it doesn't look bad. I have tried to work the tubes in and out a few times but again no luck. I might give Crate a call again today, they were pretty helpful before but sounds like my problem is pretty ambiguous to diagnosis over the phone Link to comment Share on other sites More sharing options...
Members nuke_diver Posted October 28, 2008 Author Members Share Posted October 28, 2008 no other ideas? Link to comment Share on other sites More sharing options...
Members mrbrown49 Posted October 28, 2008 Members Share Posted October 28, 2008 no other ideas? you were doing all this work with the amp off, right? Sounds like something blew. For future reference, it's a bad idea to dime an amp that is having issues. Link to comment Share on other sites More sharing options...
Members Burningleaves Posted October 28, 2008 Members Share Posted October 28, 2008 Yeah Richey I tried the old tube thinking the AU7 was bad but same problem. Previously when it worked ok I always noticed a slight pop sound when switch from standby to on. Now I don't hear that. I looked at the based of the PCB where the socket is mounted but I don't see anything obvious. I could try resoldering it (had to do that with my wife's car to fix a cold solder issue with the dashboard) but it doesn't look bad. I have tried to work the tubes in and out a few times but again no luck. I might give Crate a call again today, they were pretty helpful before but sounds like my problem is pretty ambiguous to diagnosis over the phone Discharging the caps would be a safe bet if your going to be fiddling around inside the amp........ Did you put the tubes in correctly? You might have stuck them in such a way that they fit but are not key'd into the correct pins. Link to comment Share on other sites More sharing options...
Members nuke_diver Posted October 28, 2008 Author Members Share Posted October 28, 2008 Amp was off Diming it was to see if there was any signal at all, I didn't leave it there for more than about a second The tubes can only go in one way as far as I can see. Any attempt to do something else would cause a bent pin. I'm not keen on the idea of trying to resolder the mount since I really don't know or think that is the problem. I have changed all the tubes already without any problems. If the mount was having an issue would the result be that there was very low (but not no) signal? This was V3 (phase inverter I think) tube. No other tubes were touched Link to comment Share on other sites More sharing options...
Members Burningleaves Posted October 28, 2008 Members Share Posted October 28, 2008 Amp was off Diming it was to see if there was any signal at all, I didn't leave it there for more than about a secondThe tubes can only go in one way as far as I can see. Any attempt to do something else would cause a bent pin. I'm not keen on the idea of trying to resolder the mount since I really don't know or think that is the problem. I have changed all the tubes already without any problems. If the mount was having an issue would the result be that there was very low (but not no) signal? This was V3 (phase inverter I think) tube. No other tubes were touched Ok....Well one direction might be to put the old tubes back into the amp and start the de-bugging process a bit more in depth. I can't get the link to work for some reason but if you google ...amp debugging .... you should be able to navigate to the Tube Amplifier Debugging Page It's a pretty good resource and worth a look (imo). Link to comment Share on other sites More sharing options...
Members nuke_diver Posted October 28, 2008 Author Members Share Posted October 28, 2008 Well the first time I talked to crate when I had an initial issue with this amp the technical support was great. This time, not so much. The guy seemed fixed on the fact that the tube had been replaced even though I mentioned that I put the original tube back in. He thought that the amp probably needed to be rebiased (though I was under the impression that these were cathode biased and therefore did not need to be rebiased after a tube change). Looking to wagdog and Verne to chime in since I know they've done major refits to their V series amps Link to comment Share on other sites More sharing options...
Members nuke_diver Posted October 28, 2008 Author Members Share Posted October 28, 2008 Thanks Burning Leaves I'll try and check that out BTW I did put the original working tube back in but it does work either Link to comment Share on other sites More sharing options...
Members Burningleaves Posted October 28, 2008 Members Share Posted October 28, 2008 Thanks Burning Leaves I'll try and check that outBTW I did put the original working tube back in but it does work either Yup. I figure you might as well have them in there though because you knew they had been working at the time of removal. As others mentioned already it seems it could be a socket issue. Might be that you will only notice a crack or something loose when the socket is moved. Link to comment Share on other sites More sharing options...
Members Burningleaves Posted October 28, 2008 Members Share Posted October 28, 2008 When you took the amp out of teh cab to check the socket did you smell anything funny? Like a burned smell? Link to comment Share on other sites More sharing options...
Members wagdog Posted October 28, 2008 Members Share Posted October 28, 2008 Looking to wagdog and Verne to chime in since I know they've done major refits to their V series amps I'm certainly no technician... You need to discharge the caps... Then I would visually check if one of the contacts in the tube socket got messed up and try to fix it if it did. Failing that... does the v18 have an effects loop? If you plug into the effects loop with your guitar, do you get output? Link to comment Share on other sites More sharing options...
Members nuke_diver Posted October 28, 2008 Author Members Share Posted October 28, 2008 No smells everything seemed normal until I turned it on and did not hear the "pop" that I usually hear when I first turn it on. Initially I thought it was the AU7 but it was infact an indication of the problem Based on Tube Amplifier Debugging Page they seem to suggest that the problem I have (low volume) is mostly a preamp tube issue. Maybe just bad luck that the swapping of 1 tube (moving the amp stage to change out V3 caused V1 or V2 to fail). If I get it working I will test the amp with no tube in V1, V2 and V3 to see what the effect is...assuming that doesn't smoke the amp Wagdog, no effects loop, I take a look at the contacts when I get home, if I have time tonight...its a late night at work I'm afraid Link to comment Share on other sites More sharing options...
Members nuke_diver Posted October 28, 2008 Author Members Share Posted October 28, 2008 oh just to clarify that it is not the cable from the guitar or the guitar, plugged into the AD30 and it is fine Link to comment Share on other sites More sharing options...
Members mike42 Posted October 29, 2008 Members Share Posted October 29, 2008 Since none of the tech gurus have responded to this I'll make a suggestion.My chart shows the 12AU7 is much lower gain than the AX7. If you subbed all of these, you probably lowered the total gain in the preamp by a bunch. If you only subbed one tube that's probably not the cause of output loss. However- the fact that you've got some output suggests that the basic circuit is mostly OK, and you may be getting that small output "bleeding" through a bad tube in another preamp stage. Sounds like a strange coincidence for one tube to fail just a you swapped another, but it happens. I would try swapping the other preamp tubes - but not with all AU7s. Link to comment Share on other sites More sharing options...
Members Mr Songwriter Posted October 29, 2008 Members Share Posted October 29, 2008 The tubes can only go in one way as far as I can see. Any attempt to do something else would cause a bent pin. I'm not keen on the idea of trying to resolder the mount since I really don't know or think that is the problem. I have changed all the tubes already without any problems. If the mount was having an issue would the result be that there was very low (but not no) signal? This was V3 (phase inverter I think) tube. No other tubes were touched I think you've damaged a pin or two in the tube mount, if you've made the amp safe, you could try testing for continiuty with a DMM probe in each of the sockets holes and the other probe testing the point where it's connecting to the board. Link to comment Share on other sites More sharing options...
Members nuke_diver Posted October 29, 2008 Author Members Share Posted October 29, 2008 Well I came home and checked again. First I checked to see if all the tubes were working. Turned it on, turned off the lights all 5 tubes glowing nicely. Flipped on the switch and a nice light blue glow coming from the EL84's but still no sound. I looked all over unplugged replugged the speaker checked the connections to the speaker from the plug, checked the pins in the tube mounts, everything seemed fine. I tried to test out the connections from the sockets to the board but I didn't have enough hands so I quit. Put it back together and tried just one more time thinking another call to make a warrenty claim was on the way.... AND IT WORKED!!!!!!!!!!!!!!!!!!!!!!! :love::poke: I can only guess right now but maybe the speaker plug or something else wasn't quite right even though I thought it was and redoing everything even if they seemed ok fixed the error. I don't really care I got my amp back after a {censored}ty couple of days at work and at home and I couldn't be happier. Just played for 2 1/2 hrs. I'm pretty happy with the 12AU7 too, much more responsive than before, it doesnt have the hair trigger going from too soft to too loud now, much more controllable. Thanks everyone for the help, you guys rock! :rawk: Link to comment Share on other sites More sharing options...
Members Ryan Trevisol Posted October 29, 2008 Members Share Posted October 29, 2008 *whew* disaster averted! Link to comment Share on other sites More sharing options...
Members wagdog Posted October 29, 2008 Members Share Posted October 29, 2008 Glad to hear. Link to comment Share on other sites More sharing options...
Members Gilgators Posted October 29, 2008 Members Share Posted October 29, 2008 Sorry I'm chiming in late, but this is a related story. I have a V16 (Palomino) I used at a gig this past weekend. During set-up, the amp is plugged in to an outlet -- but no guitar is plugged into the amp. Well, I hear this brief but loud electrical crackling. I think it's coming from the PA. Can't be from my amp, because no guitar is plugged in yet. We start playing the first song of the first set. The electrical crackling comes back, and this time I'm SURE it's from my amp. While the rest of the band keeps the song going (we have two guitar players), I quickly change the guitar cable. Not the problem. I change guitars. Not the problem. So I bypass the amp and go direct into the board. Finish the first set that way, and it goes without a hitch. Couldn't hear myself well in the monitors, but otherwise okay. During the first break, I open up my amp. I'd swapped out preamp tubes the night before (12AT7 for lower gain). I'd also TESTED it the night before, and it played fine. But at this point, I was willing to try anything. Nope, not the tube. Finally, at my wits' end, I plug my amp into a different outlet. * BINGOOOOOOOOO! * Moral of the story: check the simplest things first. Link to comment Share on other sites More sharing options...
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