RE-TUBING Problems!!!

[peedo_deedo]

hello everyone. i decided to replace the power tubes of my Mesa Mark IV. i noticed as i was taking the tubes out that 2 of them have a broken middle pin. its not the pins that goes around the tube but the one in the middle. (its the black part of the pic attached.) im not sure if they are still inside the socket or not as i can't see clear enough. im thinking that if i put the new tubes in, they will no go all the way in if the pin is still left inside the socket.

anyone here knows how to safely take them out, or better yet how to handle this situation? it's my first time dealing with tube amps and i dont wanna mess up my mark iv. all your help and suggestions will be greatly appreciated.

thanks a lot

 

[beej]

I'm no expert at this, but with the amp off (and a lamp or flashlight), see if you can find the center piece in the tube socket. You can safely pry it out if it's there and easy to get (pliers, etc.). It's not a pin, so shouldn't be too bad to get out.

If you haven't worked around amps, I'd strongly suggest not opening it up- the power capacitors can hold a lethal voltage, long after the amp is off, and you don't want to accidentally brush against them. But there won't be any power to the tube sockets so you're ok to try and get it out.

If it requires prying or it's stuck, I'd say take it to a tech. You don't want to crack the tube sockets or mess them up, then you'd be back at the techs place anyway.

 

[Mick]

Take it to a pro, like beej said. I know what I´m talking about.
I strongly recommend replacing it with Mesa Tubes because you can´t adjust the bias in the Mesa amps unless you mod the bias circuit a bit.
If you don´t understand a word of all of this. recommend even more to take it to a pro.

Mick

 

[MusicManJP6]

Sorry to hear about your amp problem! As long as the GT tubes have a distortion rating between 4 and 6 then the new tubes are OK to use with your Mesa.

As for the real problem - you MIGHT be able to pry the center piece out, but I would recommend using something sticky (double sided tape maybe?) to try to pull the piece straight out. Hopefully it's not stuck to where it won't come out easily. If you need to pull the chassis to take a better look just don't touch any of the capacitors and you should be fine. If you turn off your amp by hitting the power switch first (instead of hitting the standby then the power) then the capacitors should be drained and you don't have to worry about getting shocked. Good luck!

 

[INMT]

Actually on most tube sockets they ( the alignment pin) will push right through and end up on the inside of the amp. Since you don't want to leave those little pieces floating around in there you will obviously have to remove the amp chassis from it's case. With a Mesa that's a matter of 4 to 6 screws.
When you remove tubes remember slightly wiggle them in a slight circular or back and forth rocking motion till they become loose enough to pull straight out.
Also don't forget to use tubes rated for the fixed bias on Mesa's

 

[Spudmurphy]

I too also believe that the pin will come out the other side of the the valve base holder,

I'm not even sure if the bit that has snapped off is solid or just a sleeve?

If it is solid you could try drilling a small hole into it using a [ame="http://www.amazon.co.uk/Faithfull-Pin-Vice-Size-0-1mm/dp/B0001IWTVY"]pin vice[/ame]. These are small hand held drills that are used a lot in model making (I don't know if you have such a thing as Games Workshop Sc fi models but I know that they sell them).
All you would need to do is drill a very small pilot hole into it, screw in a self tapping screw and you could then yank it out with a pair of pliers.

If the "snapped bit" is hollow you could use one of [ame="http://www.amazon.co.uk/Rawlplug-240-Card-Rawlnuts-30mm/dp/B0001P0KAO"]these[/ame]
insert it into the sleeve, and when you tighten the screw it will swell up inside the rubber and grip on the sleeve - once again extract it with a pair of pliers.
Just keep away from the transformers and you will be ok.

But as has been said if your diy skills are not up to it - take it to a pro.

 

[meenahga]

To re-iterate some good advice, If you are not at all sure, do not poke around in your tube amp. The caps can hold very high voltages that can kill!

 

[peedo_deedo]

thanks a lot for the advices. i tried prying it out but it didnt work. i think that i actually pushed it even higher

i dont wanna play (or ruin!) with the amp so i will just take it to Mesa Boogie, since im only 30 miles away from them anyways. thanks a lot for your suggestions.