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C64/VIC 20 in video was Re: [midatlanticretro] Re: Plus/4

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  • Christian Liendo
    I remember a cable access show that used the VIC20.. I don t know how he did it without a genlock, but he had text on the bottom of the screen in the familiar
    Message 1 of 26 , Apr 8, 2009

      I remember a cable access show that used the VIC20.. I don't know how he did it without a genlock, but he had text on the bottom of the screen in the familiar VIC-20 font... The show was "Rapid T Rabbit" and it was on Manhattan Public Cable Access.

    • Ray Sills
      If you put the video output of a VIC-20 (or any other device that could output NTSC) through a frame-sync .. that would make it work. A frame-sync is
      Message 2 of 26 , Apr 8, 2009
        If you put the video output of a VIC-20 (or any other device that
        could output NTSC) through a "frame-sync".. that would make it work.

        A frame-sync is essentially a RAM buffer that will store a frame of
        incoming video, and then play it back in sync with an external
        reference.
        TV stations do that all the time for incoming video feeds... since
        there is no way to send timing signals to a remote source, so that it
        would
        be "in time" with local sources. All signals need to be in time in
        order to matte a source to another video signal.. or to effect a
        dissolve from one source to another. You can make a hard switch, but
        then you run the risk of the whole system going out of time for a few
        frames, and you would see the disruption on air.

        One issue with using a frame-sync is that unless you -also- delay the
        audio from the remote source, the video will be OK but the sound will
        be ahead of the video, which is noticeable when you see a talking
        head. (The old "lip-sync" issue). The situation can get worse when
        stations use fancy digital switchers, since the video gets delayed on
        -all- sources, not just the remote ones, If you see a TV show where
        the audio is so far out of whack that it looks like a bad sci-fi
        movie from another country, then you know there are uncompensated
        audio paths.

        73 de Ray



        On Apr 8, 2009, at 1:15 PM, Christian Liendo wrote:

        >
        > I remember a cable access show that used the VIC20.. I don't know
        > how he did it without a genlock, but he had text on the bottom of
        > the screen in the familiar VIC-20 font... The show was "Rapid T
        > Rabbit" and it was on Manhattan Public Cable Access.
        >
        >
        >
        >
      • B Degnan
        ... What do I look like, a store? just kidding I probably could be a store, sure I will sell you one, name your price (privately). Bill
        Message 3 of 26 , Apr 8, 2009
          Brian Cirulnick wrote:
          --- In midatlanticretro@yahoogroups.com, B Degnan <billdeg@...> wrote:
            
          I'll sell  you a Plus/4 boxed and working if you want it.  Name your price.
          
          Bill
          ---------------
              
          Bill, put me down for a Plus/4... (if you've got extras)
          Bring it to the MARCH fest, and I'll pay you then...
          
          ttyl
          Brian C.
          
            
          What do I look like, a store?  just kidding I probably could be a store, sure I will sell you one, name your price (privately).
          Bill
        • saturnine11
          ... Hi Mike, I use a simpler, more effective method. Power supply negative to cap negative. Power supply positive to 30kohm resistor to cap positive.
          Message 4 of 26 , Apr 11, 2009
            --- In midatlanticretro@yahoogroups.com, Mike Loewen <mloewen@...> wrote:
            >
            >
            > I tore apart my IMSAI in order to remove the four large electrolytic
            > capacitors for testing/reforming. There are two 9500uf-30VDC caps and two
            > 95000uf-15VDC caps. Here's the rig I put together for bringing them back
            > to life:
            >
            > http://sturgeon.css.psu.edu/~mloewen/Oldtech/IMSAI/Reforming-L.jpg
            >
            > I put this together after reading many documents about testing old
            > capacitors. Hidden behind the cap is an 8K power resistor in series with
            > the cap. The small meter is measuring the voltage output from the the
            > power supply (a HP 6443B 0-120VDC/2.5A unit), in this case 25.0 volts.
            > The large meter is measuring the current flowing through the cap, 0.11ma.
            > The voltage across the cap is 24.7V at this point.
            >
            > I started out by raising the voltage by steps, from 3-6-9-12-15-20-25,
            > watching the current and making sure it went no higher than 0.5ma. At
            > each step, I'd let the cap charge up until the current was down to about
            > .05ma then increase the voltage. Once I got to 25.0 volts, I let it sit
            > for a while until the current was down to .03ma.
            >
            > So far I've done one of the 9500uf caps. I'm hoping this procedure is
            > effective. How about it, Dan and the rest of the electronics gurus?
            >
            >
            > Mike Loewen mloewen@...
            > Old Technology http://sturgeon.css.psu.edu/~mloewen/Oldtech/

            Hi Mike,

            I use a simpler, more effective method. Power supply negative to cap negative. Power supply positive to 30kohm resistor to cap positive. Voltmeter across 30kohm resistor. Cap voltage determines the increments I raise the supply voltage in. For low voltage caps like yours, I just raise it smoothly until voltage hitting the cap is its rated voltage... but never exceeding 1ma to get there. If the cap can't be slowly raised to rated voltage without going over 1ma, the leakage current is too high and the cap is bad.

            If the cap settles down to a low leakage at rated voltage (0.5ma or preferably much less), I'll next push the cap... by raising supply V until V hitting cap is 10% OVER the rated voltage... so 33volts and 16.5 volts for your examples. All the while keeping an eye on the leakage current as before.

            Depending on how long since use, I'll let them sit at that voltage and low leakage rate for at least 30 mins... up to several hours... Then to finish, I slowly discharge the cap with a 1k resistor.

            Since electrolytics are chemical devices, they can explode from overpressure caused from overheating from too high a *leakage current* (not the same as the charge current!) and otherwise be dangerous to work with if you don't know what you're doing. Always wear goggles.

            JS
          • Bill Dromgoole
            ... From: saturnine11 To: Sent: Saturday, April 11, 2009 11:53 AM Subject: [midatlanticretro] Re:
            Message 5 of 26 , Apr 11, 2009
              ----- Original Message -----
              From: "saturnine11" <js@...>
              To: <midatlanticretro@yahoogroups.com>
              Sent: Saturday, April 11, 2009 11:53 AM
              Subject: [midatlanticretro] Re: Capacitor testing


              --- In midatlanticretro@yahoogroups.com, Mike Loewen <mloewen@...> wrote:
              >
              >
              > I tore apart my IMSAI in order to remove the four large electrolytic
              > capacitors for testing/reforming. There are two 9500uf-30VDC caps and two
              > 95000uf-15VDC caps. Here's the rig I put together for bringing them back
              > to life:
              >
              > http://sturgeon.css.psu.edu/~mloewen/Oldtech/IMSAI/Reforming-L.jpg
              >
              > I put this together after reading many documents about testing old
              > capacitors. Hidden behind the cap is an 8K power resistor in series with
              > the cap. The small meter is measuring the voltage output from the the
              > power supply (a HP 6443B 0-120VDC/2.5A unit), in this case 25.0 volts.
              > The large meter is measuring the current flowing through the cap, 0.11ma.
              > The voltage across the cap is 24.7V at this point.
              >
              > I started out by raising the voltage by steps, from 3-6-9-12-15-20-25,
              > watching the current and making sure it went no higher than 0.5ma. At
              > each step, I'd let the cap charge up until the current was down to about
              > .05ma then increase the voltage. Once I got to 25.0 volts, I let it sit
              > for a while until the current was down to .03ma.
              >
              > So far I've done one of the 9500uf caps. I'm hoping this procedure is
              > effective. How about it, Dan and the rest of the electronics gurus?
              >
              >
              > Mike Loewen mloewen@...
              > Old Technology http://sturgeon.css.psu.edu/~mloewen/Oldtech/

              Hi Mike,

              I use a simpler, more effective method. Power supply negative to cap
              negative. Power supply positive to 30kohm resistor to cap positive. Voltmeter
              across 30kohm resistor. Cap voltage determines the increments I raise the
              supply voltage in. For low voltage caps like yours, I just raise it smoothly
              until voltage hitting the cap is its rated voltage... but never exceeding 1ma to
              get there. If the cap can't be slowly raised to rated voltage without going
              over 1ma, the leakage current is too high and the cap is bad.

              If the cap settles down to a low leakage at rated voltage (0.5ma or
              preferably much less), I'll next push the cap... by raising supply V until V
              hitting cap is 10% OVER the rated voltage... so 33volts and 16.5 volts for your
              examples. All the while keeping an eye on the leakage current as before.

              Depending on how long since use, I'll let them sit at that voltage and low
              leakage rate for at least 30 mins... up to several hours... Then to finish, I
              slowly discharge the cap with a 1k resistor.

              Since electrolytics are chemical devices, they can explode from overpressure
              caused from overheating from too high a *leakage current* (not the same as the
              charge current!) and otherwise be dangerous to work with if you don't know what
              you're doing. Always wear goggles.

              JS



              ------------------------------------

              I don't see how your method is simpler or more effective than Mike's method.
              I probably just don't understand your method.

              If I understand you correctly you are putting a 30 Kohm resistor in series with
              the Capacitor being rejuvenated and measureing the voltage across the resistor.
              When the leakage current is equal to one milliampere the meter would read 30
              volts and at 0.5 ma it would read 15 volts, etc.
              The voltage accross the capacitor is unknown unless you have a seperate meter to
              see the output voltage from the power supply.
              You would then need to subtract the two voltages to get the capacitor voltage
              unless you have a third meter to measure capacitor voltage.
              The purpose of this exercise to to make a bad cap good again, if possible.

              As you can see, I don't fully understand your method.
            • saturnine11
              ... the Capacitor being rejuvenated and measureing the voltage across the
              Message 6 of 26 , Apr 12, 2009
                --- In midatlanticretro@yahoogroups.com, "Bill Dromgoole" <drummy@...> wrote:
                > I don't see how your method is simpler or more effective than Mike's method.
                > I probably just don't understand your method.
                >
                > If I understand you correctly you are putting a 30 Kohm resistor in series with
                > the Capacitor being rejuvenated and measureing the voltage across the resistor.
                > When the leakage current is equal to one milliampere the meter would read 30
                > volts and at 0.5 ma it would read 15 volts, etc.
                > The voltage accross the capacitor is unknown unless you have a seperate meter to
                > see the output voltage from the power supply.
                > You would then need to subtract the two voltages to get the capacitor voltage
                > unless you have a third meter to measure capacitor voltage.
                > The purpose of this exercise to to make a bad cap good again, if possible.
                >
                > As you can see, I don't fully understand your method.
                >

                << If I understand you correctly you are putting a 30 Kohm resistor in series with > the Capacitor being rejuvenated and measureing the voltage across the resistor.>>
                ** That is correct. That configuration makes the approach simpler because of less equipment needed. You only need a variable PSU, voltmeter, and 3-5watt 30k resistor.

                << When the leakage current is equal to one milliampere the meter would read 30 volts and at 0.5 ma it would read 15 volts, etc.>>
                ** Correct.

                << The voltage accross the capacitor is unknown unless you have a seperate meter to see the output voltage from the power supply.>>
                ** Most variable PSU's have an output Volt/Ammeter built in. So you can either infer V across cap by subtracting the voltage drop across resistor from your PSU's voltage readout... OR you can just move one lead of your VDrop meter over to the cap's opposite terminal.. since you've already got one lead on it where the resistor is.


                << unless you have a third meter to measure capacitor voltage. The purpose of this exercise to to make a bad cap good again, if possible.>>
                ** Yeah, the purpose is to reform the oxide layer on the foil roll within the cap... assuming there's enough electolyte left in there to where it's not dried out, and assuming there's not shorts or other problems.

                To recap, my method is simpler just in equipment setup, and also potentially gives you a longer cap life by the 10% push (the point of which is to give you more of an oxide layer.. well within the design limits of the caps).

                jS
              • Evan Koblentz
                Hello new guy. Please introduce yourself, how you found us, etc.
                Message 7 of 26 , Apr 12, 2009
                  Hello new guy. Please introduce yourself, how you found us, etc.
                  > I use a simpler, more effective method .... JS
                  >
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