vh4: 6l6 red plate?

[opiateofthemasses]

So I just threw in a fresh set of Ruby 6l6's yesterday, as well as a whole new set of pre's. Got them from Valve queen. everything was fine and dandy, I biased to about 65-66ma on the brown wire pair, and the blue was about 61-62.

I was just plucking around at low volume earlier when I started hearing hum, and got a volume loss. I looked over and the right 2 6l6's (looking from the front of the amp) were red plating. Started getting the burning smell so I hit the standby switch and they cooled down to normal. I re-checked the bias and it was the same as it was yesterday give or take 1ma. When I was checking the bias (standby off) I didn't get any unusual activity or anything and the tubes started acting normal again.

Anyone have any idea about what might have caused this? Again it was only the blue wire pair that red plated. I also lowered the bias down to 60-57. I made a video of the inside of the amp while I was doing this as well, but didn't see anything crazy...no blown fuses or anything melted or whatever.

 

[jonl]

2 questions
Did you switch the toggle switch over from EL34 to 6L6?
Isn't the ohms read in pairs of 35 mA rather than 60 something?

 

[opiateofthemasses]

2 questions
Did you switch the toggle switch over from EL34 to 6L6?
Isn't the ohms read in pairs of 35 mA rather than 60 something?

Yea the switch is on 6l6....is it supposed to be 35ma for one pair?? For 6l6's?


Edit: Just found the bias runthrough again and here's what it says

Recommended current settings for pairs in a VH4:

5881: 50 mA
6L6: 60 to 70 mA
EL34 60 to 70 mA
6550, KT66, KT88: 80 mA


It's apparently only 35ma for a pair on the VH4s because of the output transformers. Makes sense

 

[opiateofthemasses]

this is what I got going on right now....nothing crazy, except that one tube is a lot more blue than the others.

 

[jonl]

Shit man, I don't know then...
I'd check to make sure the tube socket clips aren't open to wide.
I would swap the tubes around to see if the problem follows the tubes or stays with the sockets

 

[Peter Diezel]

As Jonl said, please check the clamps inside the power tube sockets.

FIRST UNPLUG THE AMP !!!

 

[opiateofthemasses]

As Jonl said, please check the clamps inside the power tube sockets.

FIRST UNPLUG THE AMP !!!

Ill have a go at that then, but those little peckers are tricky to get to.

 

[jonl]

As Jonl said, please check the clamps inside the power tube sockets.

FIRST UNPLUG THE AMP !!!

Ill have a go at that then, but those little peckers are tricky to get to.

Use a metal dental pick

 

[Peter Diezel]

Yes and spray a LITTLE BIT cleaner on the tube pins.

For the test move the power tubes slightly when the amp
is in running mode. There should be no noise.

 

[opiateofthemasses]

Yes and spray a LITTLE BIT cleaner on the tube pins.

For the test move the power tubes slightly when the amp
is in running mode. There should be no noise.

Well I don't have any cleaner on hand, but I did the test and got no noise a high volume. The tubes have been fine ever since that first issue....it's just really weird, 2 tubes red plate, then everything is back to normal with no issues.

 

[Peter Diezel]

Makes me sleep well

Good night,
Peter

 

[opiateofthemasses]

Maybe it could have been a connection issue? The middle solder look a bit cracked? Just don't want this to happen during a show.

 

[jonl]

Hit it with a little solder
We had to do that

 

[opiateofthemasses]

Hit it with a little solder
We had to do that

Had to do what? Wait, u and moose?

 

[MOOSEHEADS]

Hit it with a little solder
We had to do that

Had to do what? Wait, u and moose?

I havnt ever touched a solder joint in a Diezel.

 

[opiateofthemasses]

Well color me confused then.

 

[jonl]

Sorry,
I ment my local friend Bill and I had to solder down a joint on my amp.
So it's not a bad idea to secure the joint with a little solder like I did.

 

[opiateofthemasses]

Ok that makes sense lol. I'm taking it to my tech on Tuesday to get the socket connections checked out.

 

[jonl]

It's very easy to do...
It's free to do it yourself
http://billmaudio.com/wp/?page_id=171

 

[opiateofthemasses]

It's very easy to do...
It's free to do it yourself
http://billmaudio.com/wp/?page_id=171

Did that already, I was talking about the solder connections. I don't have an iron, or any soldering experience at the moment. I do plan on learning though, so I can do this crap myself. I just want to see if my "bad solder" theory is true.