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    Installing VTA Board - Strange Pin Connections to Sockets on Existing setup

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    aguaazul

    Posts : 45
    Join date : 2012-07-08
    Location : Livermore, CA

    Installing VTA Board - Strange Pin Connections to Sockets on Existing setup

    Post by aguaazul on Mon Jun 09, 2014 7:51 pm

    My ST-70 was brought up to spec a few years ago. The tech installed new milSpec sockets.
    The connections to Pin(s) 1 & 2 - 22 & 23 are just a simple 1k resistor to pin #5 on the sockets. Pin 6 has nothing connected to it.
    Should I put the resistor back @ 5 - 6 and connect 6 to the new Driver Board? Did he use a socket that needs this configuration?
    Thanks,
    Blue

    aguaazul

    Posts : 45
    Join date : 2012-07-08
    Location : Livermore, CA

    Re: Installing VTA Board - Strange Pin Connections to Sockets on Existing setup

    Post by aguaazul on Mon Jun 09, 2014 7:58 pm

    Here is a picture:

    Resistor Connection

    Bob Latino
    Admin

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    Join date : 2008-11-26
    Location : Massachusetts

    Re: Installing VTA Board - Strange Pin Connections to Sockets on Existing setup

    Post by Bob Latino on Mon Jun 09, 2014 9:16 pm

    aguaazul wrote:My ST-70 was brought up to spec a few years ago. The tech installed new milSpec sockets.
    The connections to Pin(s) 1 & 2 - 22 & 23 are just a simple 1k resistor to pin #5 on the sockets. Pin 6 has nothing connected to it.
    Should I put the resistor back @ 5 - 6 and connect 6 to the new Driver Board? Did he use a socket that needs this configuration?
    Thanks,
    Blue

    You can do either ..(1) Run the 1K resistor directly to pin #5 or (2) run a wire to pin #6 and run the 1K resistor across pins 5 and 6. Pin#6 is NOT USED in octal output tubes so pin 6 is just a tie off point for the 1K resistor. It is interesting to note that all the FACTORY WIRED Dynaco ST-70's ran the resistor directly from the driver board to pin 5 - BUT - If you wired up the ST-70 from a KIT, the kit assembly manual told you to run the wire from the driver board to pin 6 and then the 1K resistor across pins 5 and 6. See photo below .. Note that on the factory wired amp there is no connection on pin #6 - it is empty on all four output tube sockets.

    Bob



    aguaazul

    Posts : 45
    Join date : 2012-07-08
    Location : Livermore, CA

    Re: Installing VTA Board - Strange Pin Connections to Sockets on Existing setup

    Post by aguaazul on Tue Jun 10, 2014 12:45 am

    Great News!

    Montana Way, yep, I've got a prewired VTA driver Board that I'm installing. (nice fish)

    Bob, Thank you for explaining it to me. I'll run the 1k resistor across 5-6. It will give me easier wiring in the long and short of it all. I saw in the schematics that 6 had no connections. Now I'm sure.

    I'm looking forward to hearing this new VTA driver board!

    Blue

    tubes4hifi
    Admin

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    Join date : 2008-11-30

    Re: Installing VTA Board - Strange Pin Connections to Sockets on Existing setup

    Post by tubes4hifi on Tue Jun 10, 2014 11:41 am

    nice photo comparison Bob, I think we get this question at least once a month

    aguaazul

    Posts : 45
    Join date : 2012-07-08
    Location : Livermore, CA

    Re: Installing VTA Board - Strange Pin Connections to Sockets on Existing setup

    Post by aguaazul on Tue Jun 10, 2014 12:24 pm

    I searched the forum with at least 3 different queries before I posted. What could I have searched to find this answer?

    stewdan

    Posts : 161
    Join date : 2010-03-07
    Age : 78
    Location : Houston Texas

    Re: Installing VTA Board - Strange Pin Connections to Sockets on Existing setup

    Post by stewdan on Tue Jun 10, 2014 12:35 pm

    Hi aquaazul -- actually, I think you would have had to know exactly what to look for ... sometimes I can find things via queries and sometimes it just a question of knowing what to look for, since I saw it once or twice before.

    The info that you needed is in a STICKEY with the title: " Differences between factory wired and kit built ST-70 - photos .. "

    Stew

    aguaazul

    Posts : 45
    Join date : 2012-07-08
    Location : Livermore, CA

    Re: Installing VTA Board - Strange Pin Connections to Sockets on Existing setup

    Post by aguaazul on Tue Jun 10, 2014 12:46 pm

    That makes sense Stew. I try hard to find the answers myself without bothering others, so I’m grateful that I was able to get the help I needed so quickly. I’ll take your advice, read through the STICKY posts.

    I read the post on Safety, very valuable info for sure.

    I got the old driver board out, found the brown goo issue on the choke, ordered the Triode model (found that one in a search). Will take the time now to do a little polishing while I’m waiting for shipping ;-)


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