Tube blowing simual class mark IIc+

[cremona]

Hope its ok i moved my questiona to here again.

Amp played fine for around a week after i got it , then started a humming noise for 7 seconds then blew one of the el34`s (the one closest to the instrumet input)

Installed two new JJ el34 `s

As soon as I swiched on the standby the same tube blew in a blase of purple light.

What would you do ? :roll:

Amp is in simual class mode, and everything was turned to zero before flicking the standby on

 

[Boogiebabies]

Tension the tube sockets and connect pins 1 and 8 on the outer sockets before trying any other tubes.

 

[cremona]

Tension the tube sockets and connect pins 1 and 8 on the outer sockets before trying any other tubes.

Ok

I read the other post many many times now but i still can see what exactly it is im suppose to do.
And reading the post it seemed that connecting the pins diddent do the trick and therefor the amp was send to mesa or am i missing somthing ?

Tension the tube sockest , tension means streching acoring to my dictonary, but i dont see enyway i could do that to the tube sockest.


connect pins 1 and 8 on the outer sockets before trying any other tubes.[/quote]

The outer sockets , do you mean the ends of the sockets where the tube goes in under the board ?

There are no numbers so i have no clue where i shuld connect what with what.?

And when the have been connected what shuld i do next buy new tubes a try again i use the old or ?

And what completly escapes me is why im supposed to rewire the tube sockest when this amp have been working as it is for 25 year ?

Soory but i really wanna know exactly what im doing and before i do enything that could potentialy destroy my amp.


Your help is extremly valuble to me.

Thanks

 

[Boogiebabies]

Tensioning for tube sockets is to tighten the pins by moving them closer to each other so they grip the tube pin.

 

[cremona]

Thanks alot

Okay i see now, i have my solder iron and som tin, il give it a shot.

Shuld i then install the tubes again and fire it up ?

Again thanks for your time and teaching, right now i feel really alone on this and really is appricated alot.

Alll the best

 

[Boogiebabies]

You can try the JJ's again. If they go crazy or blow the fuse, they are done for.

 

[cremona]

Here is what the socket looks like (the one where the tube keeps lighting up

Its very hard to see what pins it is, if i try and compare the pics



The other el34 socket


And the whole board

 

[cremona]

I found out the pin thing, if i use the old mesa el34 tube i can see where the numbers are.

But ta da , the have allready been soldered together as it also shows in the pics.

 

[cremona]

tighten the pin hols with a push pin in all the possitions, and the tubes are tightly connect now.

Now the el34 dossnet turn bright purple, the two 6l6`s do. :roll: :roll: :roll:

 

[Boogiebabies]

Purple glow is fine as long as you don't get lightning in a bottle or blow fuses.

 

[JOEY B.]

Update:

http://forum.grailtone.com/viewtopic.php?f=3&t=15935&start=30

 

[cremona]

Ok

Fired it up this morning again, looks liked it was only one of th 6l6s that where more blue then the other tubes, (its the one closest to the el34 tha used to glow)

Amp had the same humming noise as before but not as loud, i then fliceked the standby button and nothing happens, so i plugged my guitar in and played alittel and it sounded great.

But the noise became louder over the next 30 secs and then pop , the the blue 6l6 diffently blew this time becasue i looked at will it happent and i could see the fire in the tube.

Im handeling it over to the repair shop, and tell them to call Mike before the do enything.

The shop carris both Mullard tubes and winged C´s

Is the mullard tubes not the org tybes for a c+ ?

thanks

 

[Boogiebabies]

If you got it too hot, you can check the screen grid resistors for 470 Ohms. They are the big ones on all four PT sockets.
While your their if you had a failure, or the amp has had a failure in the past the two 100 Ohm resistors below the speaker jacks
need to be check. You can only read them in parallel at 50 ohms. If they do not read 50, replace them. The hum may just be an imbalance
heater circuit.

 

[cremona]

If you got it too hot, you can check the screen grid resistors for 470 Ohms. They are the big ones on all four PT sockets.
While your their if you had a failure, or the amp has had a failure in the past the two 100 Ohm resistors below the speaker jacks
need to be check. You can only read them in parallel at 50 ohms. If they do not read 50, replace them. The hum may just be an imbalance
heater circuit.

Hi thanks alot

Il give this valuble info to the the repair shop

Luckely i think its in the right hands now (Mike B excluded) .

He had been repairng guitar tube amps for over 30 years and have had several makr 2`s and other simual class amps through there.


But never a C+ hope he dossent run away with it when its fixed and he hers it.

But what about tubes , he aksed if i wanted Winged C or Mullard tubes as power tubes , eny pointers ?

thanks

 

[cremona]

My amp is alive again, it was the tube sockets that where done for.


I got them all replaced and the shop found the perfect tube match fo my paticular amp ,el34 Mullards and 6l6 from tong-sol..

the fix plus new tubes was very fair priced.

Now i can rest