No sound but hum in my mark IV help a tube newb

[metalmike23]

in your original post you said there was a cracked tube and a replacement. What kind of tube was it and was it in the socket and cracked?

It was a 6L6 powertube and I didn't have another so I replaced both power tubes with EL34s

 

[Russ]

Did you happen to look at the tube sockets?

 

[metalmike23]

Did you happen to look at the tube sockets?

yes I believe so what should have I been looking for?

 

[Russ]

I am racking my brain here. Without more preamp tubes on hand to try you can't search for a bad preamp tube. Try swapping the odd 6L6 with the other two still in the amp. Really you should be able to do class A and tweed in triode and use minimal power in the el34's. Being that there is nothing coming out at but hum and effects loop is dead too I would guess preamp tubes if not a fuse. Have you checked your fuses?

 

[Russ]

discoloration or disfigurement

 

[Russ]

Sometimes tube amps can be a little odd. Some people swear against them for uncanny inconsistency and frequent failure. With proper maintenance they last forever. Did you have the amp checked when you got it? Always have an unknown amp looked over by a tech before playing it just in case something isn't right. This might be one of those cases where something isn't right. Like I said getting jarred in shipping may have knocked something loose. It might be easier to just drop it off with your tech and have him check it out. Diagnosis like this is difficult sometimes because without proper tools on hand, and a supply of replacement tubes and fuses, it might be overlooked because of something already overlooked or assumed.

 

[Russ]

you said this is your first tube amp. don't judge them all by this little mishap. take it in stride, just be glad you are not missing some really important gig.

 

[Russ]

Do you have a guitar shop nearby with relatively knowledgeable people? I could probably find your problem or be close if I could touchy feely your amp with the amount of stuff I have. How old is this amp?

 

[metalmike23]

you said this is your first tube amp. don't judge them all by this little mishap. take it in stride, just be glad you are not missing some really important gig.

Thanks alot for all your help Russ.. I'll take it into the tech and see what he has to say. I'll let you know what the problem was.
-Mike

 

[Russ]

Have you tried every channel?

Try taking out a preamp tube and see if there is any difference in the nothing but hum.

 

[Russ]

Please let me know what it is so I can have more bullets in troubleshooting. I still think it is either a short caused by shipping or a bad tube/fuse. Without checking the jacks themselves for contact with the chassis removed I can't rule out a bad input jack also. Something is just not right.

 

[metalmike23]

Have you tried every channel?

Try taking out a preamp tube and see if there is any difference in the nothing but hum.

I'll try that now

 

[Russ]

The reason that I suggested that is that if there is then you might be able to strike out the preamp side provided none of them cause a change. It would be more efficient if you had at least one known good spare 12ax7 to play with swapping them out. Something is definitely stopping the signal. Sometimes tubes go bad and you wouldn't be able to tell if it didn't fail hard enough. I still would say just take it to a tech. It can be fixed without worry within a couple of days. If you are lucky while your wait. The best thing is you won't risk breaking anything else in the process.

Was the amp insured in the shipping? If so, you may be able to recoup the cost of the repairs through the shipper. Keep that in mind.

Also how much did you pay for this head? From where (how did you buy it)?

 

[Russ]

The reason that I suggested that is that if there is then you might be able to strike out the preamp side provided none of them cause a change. It would be more efficient if you had at least one known good spare 12ax7 to play with swapping them out. Something is definitely stopping the signal. Sometimes tubes go bad and you wouldn't be able to tell if it didn't fail hard enough. I still would say just take it to a tech. It can be fixed without worry within a couple of days. If you are lucky while your wait. The best thing is you won't risk breaking anything else in the process.

Was the amp insured in the shipping? If so, you may be able to recoup the cost of the repairs through the shipper. Keep that in mind.

Also how much did you pay for this head? From where (how did you buy it)?

 

[metalmike23]

I paid 950 (it's the combo) I believe it was insured. It was won off a stores ebay auction. I keep calling the salesman and he insisted its a simple problem that mesa will work me through and says we'll do a three way call with mesa and it will be in playing condition afterwards. I don't believe him for a second. It was stupid of me to ahve it shipped out I should have just picked it up. Anyway I don't think it will be fixed by simple means. and may just go to a tech and send his store the bill. He claims it sounded great before it left the store and that the chances of any problems are minimal.

 

[Russ]

That was a reasonable price for the combo. Mesa techs are pretty good but if something worked its way free during shipping then I am pretty sure it will have to be put on a bench and gone through by a tech. If it was insured you can at least get the $ reimbursed by the store that you got it from because he will have to make the claim. I am thinking that if they had played it there and it was in working condition then it should have been ready for you to just plug your guitar into and play when it arrived so chances are you will need to take it in for repairs.

Ebay is a crapshoot nowadays. Sometimes it goes good other times it goes bad. I ordered a video from someone recently and they shipped the wrong video. I returned the video and now haven't heard from them. This video was originally purchased in the beginning of April. I think I just got burnt. Luckily it wasn't for very much if I never receive the video. There are some real sheisters on Ebay though that are out there to purposely take your money. Beware of the second chance offers and never send money. Always use Paypal.

I have gotten some good deals though where everything goes smooth. I have received 3 heads and they all worked perfectly. One had a broken tube from shipping but that was very minor and I just replaced it because I didn't like the brand and type that was in there anyway. There are some good deals to be had. Personally, I like to play anything before I get it. I figure amps can be worked on so I don't mind buying those online. Guitars are something I try not to buy on ebay though because you can't fix a bad neck or a soulless piece of wood.

Always pickup your item in person if you can that way you can make sure it gets home safely. I got two of my amps that way and everything worked out fine. I would rather pay the salestax and pickup fees if any to guarantee safe arrival. It might be difficult to get the threeway call going because sometimes the Mesa reps are busy. In addition to that you won't be sure that it is in fact a Mesa rep becasue he will have to initiate the call. If your amp wakes up then you can't complain too much other than it didn't work when it arrived. If it won't then coordinate someone with the guy you bought it from so that way at least he can't say that you were overcharged and refuse to pay the bill.

Good luck with the Mesa call and let us know what the result ends up being.

 

[metalmike23]

well luckily today after switching the preamp tubes the amp miraculously sparked to life. I was under the impression that the tubes were fine and working perfect when they left the store but I guess they were wrong or there was some problem during shipping. Now onto getting some good heavy sounds out of this thing. Thanks again Russ
-Mike

 

[Russ]

Go get yourself a full set of preamp tubes. My preamp tubes were killed on one side of two of the tubes when I got it. I think that the design may cause premature failure to the one side of two of the tubes. If placed in the amp incorrectly it would cause the amp to seem dead like you experienced. I don't know why I didn't think of that. Geez! I made a big stink of that too with some people. I have a full set of fresh tubes in there now and there are absolutely no problems. You can keep your old tubes around as spares but definitely get a new full set. I would even say get a full set of power tubes too. Just keep to the same Mesa color code and you will still be able to use them as spares there as well provided they were Mesa tubes. I am glad to hear that you got your amp working though. I was beginning to feel bad for you.