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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 Dynakitparts.com products


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    WHERE TO FIND CHASSIS BIAS PINS? HELP

    CarlB
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    CarlB
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    • Post n°1

    WHERE TO FIND CHASSIS BIAS PINS? HELP Empty WHERE TO FIND CHASSIS BIAS PINS? HELP

    Post by CarlB Mon Aug 10, 2009 6:51 pm

    I wish to purchase small bias pins or chassis pins to attach to my st70 chassis in the front. I installed the vta board and used pio caps and there is no place to fit the original bias socket. What I have to do in order to bias my tubes now is take off the bottom cover and adjust the bias while the amp is on its side(a real pain taking the amp off my bottom shelf). What I want to do is to drill 4 small holes in the front of the chassis and attach these small hollow nail like pins to the chassis from my driver tube socket pin before the resistor where I get my bias reading. They must be isolated from the chassis but screwed onto it. I tried installing a rubber gromet around the hole I made and then slide through the pin I had, but it did not look like a nice job. It worked, but maybe someone out there knows where I can purchase these pins. I think they are hollow at one end so that you can fit your voltmeter end in the hole. Also I think on the other end they can be screwed onto the chassis without making a metal to metal contact or grounding the pin to the chassis. Any feedback or help.
    thanks
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    Bob Latino
    Bob Latino
    Bob Latino
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    • Post n°2

    WHERE TO FIND CHASSIS BIAS PINS? HELP Empty Re: WHERE TO FIND CHASSIS BIAS PINS? HELP

    Post by Bob Latino Mon Aug 10, 2009 9:17 pm

    CarlB wrote:I wish to purchase small bias pins or chassis pins to attach to my st70 chassis in the front. I installed the vta board and used pio caps and there is no place to fit the original bias socket. What I have to do in order to bias my tubes now is take off the bottom cover and adjust the bias while the amp is on its side(a real pain taking the amp off my bottom shelf). What I want to do is to drill 4 small holes in the front of the chassis and attach these small hollow nail like pins to the chassis from my driver tube socket pin before the resistor where I get my bias reading. They must be isolated from the chassis but screwed onto it. I tried installing a rubber gromet around the hole I made and then slide through the pin I had, but it did not look like a nice job. It worked, but maybe someone out there knows where I can purchase these pins. I think they are hollow at one end so that you can fit your voltmeter end in the hole. Also I think on the other end they can be screwed onto the chassis without making a metal to metal contact or grounding the pin to the chassis. Any feedback or help.
    thanks

    Hi Carl and welcome to the Dynaco Tube Audio Forum,

    You should be able to fit the tube sockets back in there even though you have Russian PIO capacitors which are rather large. Bend the pins of the tube sockets back in against socket itself and then push the two front Russian PIO caps back towards the rear of the amp. This will give you enough clearance to reinsert the original tube socket. Below is photo that a customer sent to me with the VTA driver board and the Russian PIO capacitors. You should be able to get those tube sockets in there.

    Bob

    WHERE TO FIND CHASSIS BIAS PINS? HELP RussianPIO-1
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    Roy Mottram
    Roy Mottram
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    • Post n°3

    WHERE TO FIND CHASSIS BIAS PINS? HELP Empty bias test pins

    Post by Roy Mottram Sat Aug 22, 2009 2:27 am

    Hi Carl,
    Bob's suggestion was great because this is exactly what I had to do just a few days ago for a customer that had some huge WIMA caps in place. (see photo if I can attach it, the WIMAs are actually touching the sockets but they fit and work perfect).
    For anyone else though that wants an alternative, the thing to use is known as a TIP JACK,
    they fit into a 1/4" round hole and are isolated, the fit a meter probe perfectly and are great for TOP mounting on the chassis (maybe drill a hole thru the end of the slots between the output tubes) not recommended for the front panel though as they are about an inch long and extend inside quite a bit.
    www.tubes4hifi.com/107.jpg" alt=""/>
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