The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all products

    5963 an option for 12AU7 in ST120?

    Bob Latino
    Bob Latino

    Posts : 2843
    Join date : 2008-11-26
    Location : Massachusetts

    5963 an option for 12AU7 in ST120? - Page 2 Empty Re: 5963 an option for 12AU7 in ST120?

    Post by Bob Latino on Tue Apr 22, 2014 8:55 am

    VTHokie83 wrote:To the collected brain trust here, I have a question. My rectifier tube on my VTA ST-120 "wiggles" around quite a lot, to the point it will even touch against the transformer. The receptacle itself is mounted tight, but the pins that hold the tube are loose enough to give the tube that amount of play. Is that normal? If not should I replace the receptacle? Any opinions?

    Every now and then you can get a combination of loose pins on the tube socket and a rectifier tube with pins a little smaller than normal.

    Sometimes you have a rectifier tube in there with pins larger than normal and after a period of time the tube dies - SO - You put in a replacement rectifier which happens to have pins maybe just .001 to .002 inches smaller. The socket will grip the pins but not as tightly and your new rectifier is a little loose in the socket. As an aside > A few years ago JJ used some undersized material to make the pins on their octal tubes. I had an ST-70 in which a JJ KT77 tube fell out of a socket when I turned the amp upside down to measure some voltages because the pins were so thin. The vendor replaced that tube.

    If the pins get loose on a VTA amp's octal sockets you can RETENSION them by using a small flat bladed jeweler's screwdriver. Slide the screwdriver down the two sides of the triangular shaped pin on the socket that have an open end and press in. This will make the opeing slightly smaller and give a little more tension on the tube pins.


      Current date/time is Fri Dec 06, 2019 7:54 am