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    Tube contact issues

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    Bob Latino
    Admin

    Posts : 2377
    Join date : 2008-11-26
    Location : Massachusetts

    Tube contact issues

    Post by Bob Latino on Mon Nov 25, 2013 9:32 am

    Twice in the past week I have had people Email me about tubes that work in one amp but maybe won't light up or bias correctly in another amp. In both cases these issues turned out to be caused by intermittent or non contact between the tube's pins and the socket's pins. Both were solved by cleaning and/or retensioning the socket pins. A few items that can cause this ...

    1. Older amps in which dust gets into the tube socket and prevents complete contact betwen the tube and the socket
    2. Using a certain brand of tubes which have very slightly larger pins, removing these tubes and replacing them with another brand of tube whose pins are VERY slightly smaller.
    3. If you are a "tube jockey" and have cycled in quite a few tubes in and out of a socket. Every in and out cycle stretches the pins out a little.

    What to do ?

    1. Clean the pins of both the tube and the socket. Sometimes it is only dust that worked its way between the tube pin and the socket pin.
    2. Retension the socket pin. What you do is get a small flat bladed jewelers screwdriver. On the VTA amp octal sockets which have a trangular shaped socket pin with one point on the triangle open > bend in slightly the two sides of the socket pin that touch the open end of the trangle to gain more tension on the socket pin. On the noval (9 pin) driver tube sockets on the VTA amps > These have TWO socket pins that oppose each other > bend the two pins towards each other.

    Bob

    sKiZo

    Posts : 1285
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Tube contact issues

    Post by sKiZo on Tue Nov 26, 2013 3:44 pm

    Thanx for the reminder ... I'm getting out of my "tube jockey" stage now and have settled down ... more or less ... for now anyway. Sort of ... I guess ... tongue 

    Couple other socket tips I've gleaned over time is that just the heat can cause the sockets to loosen up over time, so even if you don't roll, you're bound to need to retension every now and them. Also worth noting, even the best of solder jobs can eventually crack and cause intermittent issues. A good inspection with a magnifier is in order anytime you go inside ...


    peterh

    Posts : 642
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: Tube contact issues

    Post by peterh on Tue Nov 26, 2013 4:40 pm

    sKiZo wrote:Thanx for the reminder ... I'm getting out of my "tube jockey" stage now and have settled down ... more or less ... for now anyway. Sort of ... I guess ... tongue 

    Couple other socket tips I've gleaned over time is that just the heat can cause the sockets to loosen up over time, so even if you don't roll, you're bound to need to retension every now and them. Also worth noting, even the best of solder jobs can eventually crack and cause intermittent issues. A good inspection with a magnifier is in order anytime you go inside ...

    A correct done tin/lead solder will stay correct unless it's in a corrosive environment ( but then you will have other problems )

    sKiZo

    Posts : 1285
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Tube contact issues

    Post by sKiZo on Tue Nov 26, 2013 6:48 pm

    Theoretically, anyway ...

    I just dragged my Sansui receiver up from the bench after repointing all the connections for the fuse light holders on the dial lights ... something they all have in common is eventual failure and intermittent operation due to hot/cold cycles and cracks in the solder ... heat and reflow with just a touch of new solder to prime the iron, and they're good for another 30 years ...

    Not that it wasn't fun watching the lights flash and move about at random ... pirat

    With a socket, you can also factor in the movement as you swap tubes. The ones included with the kits have a LOT of wiggle in them - not necessarily a bad thing, but I expect that can stress the solder connections also.


    Last edited by sKiZo on Tue Nov 26, 2013 6:54 pm; edited 1 time in total

    Jim McShane

    Posts : 154
    Join date : 2011-10-19
    Location : South Suburban Chicago

    Re: Tube contact issues

    Post by Jim McShane on Tue Nov 26, 2013 6:54 pm

    Bob Latino wrote:Twice in the past week I have had people Email me about tubes that work in one amp but maybe won't light up or bias correctly in another amp. In both cases these issues turned out to be caused by intermittent or non contact between the tube's pins and the socket's pins. Both were solved by cleaning and/or retensioning the socket pins. A few items that can cause this ...

    1. Older amps in which dust gets into the tube socket and prevents complete contact betwen the tube and the socket
    2. Using a certain brand of tubes which have very slightly larger pins, removing these tubes and replacing them with another brand of tube whose pins are VERY slightly smaller.
    3. If you are a "tube jockey" and have cycled in quite a few tubes in and out of a socket. Every in and out cycle stretches the pins out a little.

    What to do ?

    1. Clean the pins of both the tube and the socket. Sometimes it is only dust that worked its way between the tube pin and the socket pin.
    2. Retension the socket pin. What you do is get a small flat bladed jewelers screwdriver. On the VTA amp octal sockets which have a trangular shaped socket pin with one point on the triangle open > bend in slightly the two sides of the socket pin that touch the open end of the trangle to gain more tension on the socket pin. On the noval (9 pin) driver tube sockets on the VTA amps > These have TWO socket pins that oppose each other > bend the two pins towards each other.

    Bob
    ABSOLUTELY SPOT-ON!! If you'd like to read a bit more about tube "problems" that AREN'T tube problems look here:

    http://www.audioasylum.com/audio/tubes/messages/25/253369.html

    sKiZo

    Posts : 1285
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Tube contact issues

    Post by sKiZo on Tue Nov 26, 2013 6:58 pm

    Good read! Thanx for the link ...

    Pictures!

    http://billmaudio.com/wp/?page_id=171


    Last edited by sKiZo on Tue Nov 26, 2013 7:21 pm; edited 1 time in total

    Jim McShane

    Posts : 154
    Join date : 2011-10-19
    Location : South Suburban Chicago

    Re: Tube contact issues

    Post by Jim McShane on Tue Nov 26, 2013 7:12 pm

    sKiZo wrote:Theoretically, anyway ...

    I just dragged my Sansui receiver up from the bench after repointing all the connections for the fuse light holders on the dial lights ... something they all have in common is eventual failure and intermittent operation due to hot/cold cycles and cracks in the solder ... heat and reflow with just a touch of new solder to prime the iron, and they're good for another 30 years ...

    Not that it wasn't fun watching the lights flash and move about at random ... pirat

    With a socket, you can also factor in the movement as you swap tubes. The ones included with the kits have a LOT of wiggle in them - not necessarily a bad thing, but I expect that can stress the solder connections also.
    Another spot-on post!

    Analog Man

    Posts : 56
    Join date : 2013-09-01
    Age : 54
    Location : St. Louis, MO - On The Hill

    Re: Tube contact issues

    Post by Analog Man on Wed Nov 27, 2013 8:34 am

    Jim McShane wrote:
    Bob Latino wrote:Twice in the past week I have had people Email me about tubes that work in one amp but maybe won't light up or bias correctly in another amp. In both cases these issues turned out to be caused by intermittent or non contact between the tube's pins and the socket's pins. Both were solved by cleaning and/or retensioning the socket pins. A few items that can cause this ...

    1. Older amps in which dust gets into the tube socket and prevents complete contact betwen the tube and the socket
    2. Using a certain brand of tubes which have very slightly larger pins, removing these tubes and replacing them with another brand of tube whose pins are VERY slightly smaller.
    3. If you are a "tube jockey" and have cycled in quite a few tubes in and out of a socket. Every in and out cycle stretches the pins out a little.

    What to do ?

    1. Clean the pins of both the tube and the socket. Sometimes it is only dust that worked its way between the tube pin and the socket pin.
    2. Retension the socket pin. What you do is get a small flat bladed jewelers screwdriver. On the VTA amp octal sockets which have a trangular shaped socket pin with one point on the triangle open > bend in slightly the two sides of the socket pin that touch the open end of the trangle to gain more tension on the socket pin. On the noval (9 pin) driver tube sockets on the VTA amps > These have TWO socket pins that oppose each other > bend the two pins towards each other.

    Bob
    ABSOLUTELY SPOT-ON!! If you'd like to read a bit more about tube "problems" that AREN'T tube problems look here:

    http://www.audioasylum.com/audio/tubes/messages/25/253369.html
    These would solve the pin tension problem as well, especially if you tube roll.
    http://www.thetubestore.com/Parts-Accessories/Gold-Tube-Sockets/8-Pin-Porcelain-Ceramic-Gold-Tube-Socket

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Tube contact issues

    Post by deepee99 on Sat Nov 30, 2013 10:47 am

    I'm probably one of the buffoons Bob mentions that emailed him with what turned out to be socket issues. Pulled out my trusty KT-88s and installed some NOS U.S.-made TungSol 6550s. Was digging the sound when all of a sudden a lightning show erupted in V-1 (way better than skIZo's fantasy about rectifiers). Wrongly figured it was a lame tube, tried another, listened for a day, this time a bright red glow, like a flame in a vacuum, suddenly rolled up the plate. Pop went the Mullard rectifier, too.
    Bob rightly diagnosed poor contact on Pin 5, which is the grid No. 1 connection.  FWIW, my trusty micrometer does register a blond frog-hair's difference in diameter between the U.S. and Russian tubes, the Russians being a bit fatter.
    Two questions: there isn't a tube-tester within 200 miles of here. The multi-meter is all I have; the only short it registers on either of the two errant 6550s is between pins 2 and 7, which is the filament. Absent a full-tilt test, are they safe to plug back in, or would I risk another rectifier (or perhaps some other expensive part)?
    Second, for Analog Man: ten of those nice porcelain sockets from Tube Despot would run a guy $129.50. Other than the obvious advantage of gold contacts, do they stay better tensioned as well?

    Many thanks
    d

    sKiZo

    Posts : 1285
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Tube contact issues

    Post by sKiZo on Sat Nov 30, 2013 1:16 pm

    Welcome to the League of Extraordinary Buffoonery! I'm a charter member ... tongue 

    If it's the red plate you're worried about, I wouldn't ... one of my KT88's was cherry red, and I managed to repeat that several times during the course of my investigations, albeit for shorter periods. No apparent issues with the tube after the fix. Chances are good I shortened the effective life of the tube, but no telling how much ...

    To add insult to injury, I did it to another tube as well, just to make sure it was NOT a tube issue.

    Not a bad idea to have a couple sacrificial rectifiers handy though. I've got a couple of the Chinese tubes here that I plug in when there's any doubt. Also got a copper cap.

    PS ... you wanna see some serious tube glow, try a GOOD Chinese 5AR4 ... that's almost scary watching one of those light the room.

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