Quad ii tube sockets

[_webwasher]

The tube sockets for ef86 tubes in my quads are faulty. Often one or the other channel is not playing because the contact is bad. Wiggling the four tube helps but ist no solution. Cleaning the contacts was not very successful so my plan is to change the four vintage 9 pin sockets.

Any recommendations for the parts? They should fit the overall construction and optics, nos would be perfect because I really love that amp as is.

Thanks for reading and sharing your experience.

 

[snowman_al]

They are most likely made by Mc Murdo.
Have you looked very carefully down the sockets with a good light? You should see 2 silver 'arms' in each hole.
Quite often they have spread open a little with heat, age and valve swapping...
If they are all there you can 'adjust' the tension using a knob head pin or strong needle. Switch off and disconnect from the mains. Leave 12 hours or so before touching any thing.

Sometimes there will be only one arm as one has fallen off... Not all is lost as there is a 'spare' fork on pin 7. You can pop it out if you straighten the solder tag, so it is vertical to the chassis, then push it out bottom to top. Then transplant it to the failed position. (I have a few spare forks if you need a couple more.)

Another thing to mention is that when the Quad was designed valve pins had rounded ends. Now lots Eastern Block valves have a pointed ends. Unless you are careful, the points can go down the side of the holder forks, rather than into the proper gap, and damage the forks...

If you want to change them out search for Mc Murdo B9A valve or tube socket / holder. NOS are still out there. Make sure you get top fitting ones with the central ferrule. I would not use 2nd hand.
Personally I would use a modern holder as they have an improved circular grip on the valve pin, and do not have the pointy pin problem.

Alan

 

[_webwasher]

Very helpful, thank you very much. I’ll check the sockets as described. Would be great to fix them without changing parts

 

[Pete MB&D]

We used to stick a stout needle down the sides/edges of the sockets and force the contacts closer together, to sort loose sockets, it worked a treat back in my TV days.

Pete

 

[Tony L]

Also a large-size interdental brush, e.g. this with a good spray of Deoxit D5 (really expensive, but really good and that can will last for ages) stands a very good chance of fixing it. I’ve found it very useful with vintage valve stuff and haven’t yet had to replace a valve-base. As often as not the sockets are just full of years of crud and this gets it out and gives them a polish.

 

[_webwasher]

Thank you all for sharing. In fact the sockets are by McMurdo and some pins are out of shape. So as soon I’m motivated everything back into parts and clean with deoxid and reshape the pins. Great help from all supporter, better than changing the original sockets. Thanks!!

 

[toprepairman]

Very often I have seen the valve pins bent or even put in a wiggle to try and improve the contact. This is always a mistake and should never do done. Frequently straightening the pins can effect a cure.

 

[Barrymagrec]

Bending valve pins also often has the side effect of making the top of the valve go white....

 

[Pete MB&D]

I once cracked a crt by straightening a pin.

Pete