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Difficulty inserting tube into socket

brk303

Member
Messages
492
Now this is a bit embarrassing, but I wanted to replace EL34's with KT66's and the tube socket is so stiff I just can't manage to fully insert the tube.

I changed the preamp tubes easily and it's the first time I'm changing the power tubes in this amp, so I doubt there is any debris in the socket.

I don't have a pin straightener, but the pins seem spaced properly, so I just don't know, any ideas ?

Edit: Ok, here's bit more info:
The sockets are Belton like the pic bellow, and the retainers are pretty stiff and somewhat sharp. Tubes in were Winged C EL34 and new tubes are TAD KT66.

 
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dmagalhaes

Silver Supporting Member
Messages
1,918
Sometimes manufacturers dip the pins in solder so that they fit tight. I've dealt with tight sockets before but have never not been able to get them in. How far are they sticking out? Some tubes will not sit flush no matter what you do but we are talking only a mm or so.
 

brk303

Member
Messages
492
Socket:


How tubes were initially:


How far I can get them in now:


The left one doesn't go all the way, but the right one is even worse. I tried to turn on the amp and the left tube did light up, but the right one didn't, so it doesn't have contact.
Oh, and the same thing happens with old tubes that I took out, can't put them back in either.

Tubes:
 

brk303

Member
Messages
492
I do spread them, but the KT66 has a bigger base, so the retainers are kind of pushing the tube out rather than keeping it in place.
And I use as much force as I think is safe before risking breaking the glass.
 

wyatt

Member
Messages
4,169
Well, first things first, those tube retainers aren't designed to fit the large base of the KT66. They should have been removed (though that requires going into the chassis, which contains dangerous voltages). If retainers are necessary, you can get string retainers (even the vintage mesh kind) for KT66's, I think retaners are generally superfluous in cases where the tubes aren't suspended.

The Belton's are very popular sockets, I haven't heard much about them not fitting a tube.
 

kurtsstuff

Member
Messages
2,352
I do spread them, but the KT66 has a bigger base, so the retainers are kind of pushing the tube out rather than keeping it in place.
And I use as much force as I think is safe before risking breaking the glass.
You may have to remove them if thats the case?
 

wyatt

Member
Messages
4,169
Yes, that wouldn't hurt, but that's not the main problem. The resistance is not from the retainers it's the socket itself that is too tight.
You are rocking the tube a little back and forth, aren't you?
 

brk303

Member
Messages
492
You are rocking the tube a little back and forth, aren't you?
Yes, I watched few videos online to see how others do it and it obviously goes in easier than mine.

Ok, I managed to insert it enough to get contact, but it's still not full in.
Oh well, hopefully it will get loser with time and DeOxIt.
 
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Trout

Member
Messages
7,549
Hey,

The socket in the photo is damaged, Notice the contacts inside hole #4, #5, #6 & #7 and are both bent to one side?

I have seen this before, it often comes from not aligning the tube perfectly during insertion.

The little solder tit on the end of some tube pins acts like a pin/pick, as you rotate to get the tube aligned it pulls the contact out of position.

Then it requires extra force to install as it bends the contacts to 1 side hence difficulty inserting tube fully.

You "Might" be able to bend it back but in this case, since its multiple pins it should be replaced.
Might= follow tube retention instructions.



 
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Baxtercat

Silver Supporting Member
Messages
12,700
Yeah, broken...unfortunate turn of events.
BTW, retension, not retention [means another thing, which c/b confusing in this case].
 

brk303

Member
Messages
492
Broken ? I didn't really notice, they all look same to me, but then I'm no expert, here's another angle:

 

Koop

Member
Messages
380
Comparing the pin 6 receptacle in both photos, I think it's an optical illusion due to camera angle. I'm not convinced anything is bent or broken.

Spread the clam shell with one hand and grip the tube near the base with the other hand. Sometimes sockets will require a bit of force.
 

cap47

Member
Messages
2,276
Remove the retainers! I would bet those pins would seat in better. You are fighting with the radius on the KT66 tube base.
 






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