Blues Deville 4x10 one tube hot the other cold.

[caesparza]

Hi,

I'm making maintenance for a Blues Deville 4x10. Voltages seems to be good all over the place but I'm having an strange behavior from the amp, a couple of times I have inserted the power tubes and one of them get hot and the other is absolutely cold and doesn't get any value for voltage drop between the center tap and the plate.

What would be the first thing to check in this case?

I inserted the tube back and then it started to work. Configured the thing to dissipate around 57% (which is cold). Then decided to check a couple of NOS power tubes because there are some noises present and then got the same problem.

Thanks.
CE

[glebert]

Solder joints on tube sockets?

[alexradium]

clean the sockets from oxidation,pin sockets tend to get loose inside,try retensioning or even better replace with good items,those are the cheapest on earth.

[nevetslab]

Solder joints on tube sockets?

^^^^^^^^^ what glebert said. I see that all too often. I take it the 'cold' tube is always in the same position. De-solder and then re-solder the tube socket pins.

[mozz]

Question, since some or most of you fix these things (guitar amps in general) for a living, do you use regular solder or the lead free stuff? I have yet to buy lead free and probably never will due to have a decent lifetime supply of .010 up to .062 60/40/63/37.

[caesparza]

Did all the suggested things and tube is back to normal operartion. The amp need a couple of 12AX7 to be replaced.

Thanks again.

[Enzo]

Lead free solder sucks.

[The Dude]

Agreed! I won't buy it until they make me!

[g1]

I'll use lead-free for plumbing but that's it.

[blindboybenton]

i got about 4 rolls of the stuff when i bought up stuff from an old firm closed down. Only use it if i ever run out of leaded solder
so far only for one day in 6 yrs

[nevetslab]

I did buy a roll of the 0.031" dia stuff, but only will use it when nothing else seems to work (so far, haven't used it beyond trial and error). If I do NOT remove the lead free solder from a solder joint, applying the 60/40 leaded tin solder, the joint turns an awful off-white color, which I'll promptly redo, after sucking up the solder, and applying fresh 60/40 solder. Only then does it look good. Like the rest of ya, I hate that stuff!

[SoulFetish]

I did buy a roll of the 0.031" dia stuff, but only will use it when nothing else seems to work (so far, haven't used it beyond trial and error). If I do NOT remove the lead free solder from a solder joint, applying the 60/40 leaded tin solder, the joint turns an awful off-white color, which I'll promptly redo, after sucking up the solder, and applying fresh 60/40 solder. Only then does it look good. Like the rest of ya, I hate that stuff!

^^^^Right! They do not like each other, and I was going to make this point as well.
To follow up with a little more info: At work I use SnPb 60/40 because that's what they buy and have in stock. It's fine and we've all used it forever. But, I personally buy SnPb 63/37 eutectic solder for a couple of reasons which I think make it a better option. For instance:
"Sn 60% / Pb 40% melts in the range of 183 to 191 °C. As this alloy is heated it starts to melt at 183 °C, is slushy between 183 °C and 191 °C, and becomes fully liquid at 191 °C"
- https://fctsolder.com/eutectic-solder/
Because of this range in temperature for melting and freezing of the alloy, there is a time component may come into play. For instance, if the component being soldered moves while in this semi-solid state, it could compromise the joint (ie. if you're holding a lead while soldering).
Sn 63% / Pb 37% melts at 183˚C and ideally doesn't exhibit this semi solid state, so it is more ideal for the kind of soldering that we do.

In regards to lead free soldering, I'm wondering if some of the more modern soldering stations(Pace, JBC, and up) with much more efficient thermocouple would make lead free hand soldering an easier experience. Even using my soldering station, keeping separate tips for leaded and lead-free soldering help a lot.
I found this pdf by kester which may add some helpful info as well:
Lead-free Hand-soldering – Ending the Nightmares - Kester

I know, I know, nothing wrong with 60/40 solder.
... just sayin'

[g1]

Not sure if you guys are saying if you need/want to resolder a whole board, you remove all the lead-free first, or you just don't re-do whole boards?

[SoulFetish]

Um.... both of those