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Drain Caps on valve king 212 (same as valveking 100 head).

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  • Drain Caps on valve king 212 (same as valveking 100 head).

    I'm in the process of re-soldering a connection on r213 that broke at the the PCB.
    Before I lift the board to reconnect the loose connection I need to drain the caps.
    While I'm familiar with household AV and the caveats and precautions that go with it, I'd like to have the caps drained for obvious reasons. I'm well versed in soldering and many other types of repairs as well as using a multi-meter.
    I just want to know where the best place to drain the caps to ground with a resistor is (where on the board) as the caps are facing downward.
    I've heard that one can use pin 1 of a power tube on one side and ground on the other with the resistor?
    Any insight?
    Thanks
    Tim G.

  • #2
    Pin 3 of the output tube through a 1K (at least 1 watt) resistor to chassis ground.
    Attached Files

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    • #3
      The pin 1 referred to a preamp tube. The 100k plate resistor limits the discharge current. But that makes it achingly slow to me, so use Jazz's method.
      Education is what you're left with after you have forgotten what you have learned.

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      • #4
        Originally posted by Enzo View Post
        The pin 1 referred to a preamp tube. The 100k plate resistor limits the discharge current. But that makes it achingly slow to me, so use Jazz's method.
        Thanks a bunch! I'll keep you all posted.

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        • #5
          So I can make certain I've drained this if I measure the voltage between here and ground first with my Meter set in DC volts?
          Or better yet, while I run my bleed resistor setup on one tube socket, can I have my MM in another socket pin 3 to ground and see the voltage go down?
          ( I just want to make certain that it's safe)
          Thanks a bunch!

          Comment


          • #6
            Correct, you can monitor at another power tube pin3.
            Not sure about this model but in general standby switch must be in "run" position to discharge. I keep the standby closed like that while working as it keeps a load on the caps which prevents them from self charging.
            Originally posted by Enzo
            I have a sign in my shop that says, "Never think up reasons not to check something."


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            • #7
              Originally posted by g-one View Post
              Correct, you can monitor at another power tube pin3.
              Not sure about this model but in general standby switch must be in "run" position to discharge. I keep the standby closed like that while working as it keeps a load on the caps which prevents them from self charging.
              Please, a few more questions before i go about this

              1. Can this be done without any tubes installed? ie: all though the un populated tube sockets?
              2. And can I assume this will work if the series heater circuit is not functioning (the r213 resistor is not soldered on one end)?

              Thank you guys. I truly appreciate your time and advise.

              Comment


              • #8
                Yes and yes.
                Originally posted by Enzo
                I have a sign in my shop that says, "Never think up reasons not to check something."


                Comment


                • #9
                  Listen, the main capacitors 'store' a charge.
                  That is what should be drained.
                  Output tube pin #3, 1K resistor, ground.

                  Tubes, whether they are in or out, will not stop the charge from draining.
                  They may actually help to drain it.

                  In fact, while you have been hand wringing over this, the caps have probably discharged. (check it anyway!)

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                  • #10
                    Thanks guys!
                    My small job multimeter read 400 plus at pin 3... so yes I'm glad I drained em'.
                    I had to pull the board and flip it to get to the trace side
                    I worked great. There was a small charge saved in the other circuit where the resistor was loose. when I made the leg connection it gave off some voltage. It was probably the 4 small caps in that area. next time I'll discharge them as well.
                    Any ways, THANK YOU ALL for your help.
                    And yes, If this were my boogie or marshall they would have gone to a real tech. It's worth every penny.
                    Thanks again!

                    Comment


                    • #11
                      First time I did something (change a broken standby switch) on my Peavey VK before I had any experience with electronics, I didn't discharge the caps. I've let it sit for 2 days, thinking thats enough.The chassis was outside of the combo for at least a day...
                      Wasn't bad, but I got a tiny shock, more like a buzz in the right hand.
                      Anyway, these Valve Kings store the voltage very, very long time.
                      When working on my JTM60, I always discharge.
                      The difference is that JTM60 is great and fast in discharging itself in comparison with VK.
                      I never, ever measured more than 2 Volts while discharging on JTM60.
                      Anyway, always discharge.

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