Loading ...
Sorry, an error occurred while loading the content.

Re: [midatlanticretro] Capacitor testing (at Bill's?)

Expand Messages
  • B Degnan
    Mike, If I felt brave I might try to reproduce this. I have a similar power supply at work. Maybe I could set one of these up for the weekend of the 25th.
    Message 1 of 26 , Apr 7, 2009
    • 0 Attachment
      Mike,
      If I felt brave I might try to reproduce this. I have a similar power
      supply at work. Maybe I could set one of these up for the weekend of
      the 25th. Anyone else coming?
      Bill

      Mike Loewen 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/
      >
      >
      > ------------------------------------
      >
      > Yahoo! Groups Links
      >
      >
      >
      >
      >
      >
    • Ray Sills
      HI Bill: No, I don t have any software for the Plus/4. Everything I had went to MARCH. It s possible there might be something in the basement storage area.
      Message 2 of 26 , Apr 7, 2009
      • 0 Attachment
        HI Bill:

        No, I don't have any software for the Plus/4. Everything I had went
        to MARCH. It's possible there might be something in the basement
        storage area. Speaking of NTSC.. I used to use one of the Plus/4s at
        work, as a way to generate a title "slate" for recording music cues
        on to videotape. It worked quite well with the old Sony BVH-800 U-
        Matic 3/4" machines. But that was because the machines were not the
        least bit fussy about the quality of the video and the stability of
        the time base. Once we switched to professional Beta format, the
        Plus/4s didn't work properly. At that point, I got an Amiga (1000?)
        (Also now at MARCH) with a gen-lock board, and that worked like a
        champ. The gen-lock boards are at MARCH, too.

        73 de Ray

        On Apr 7, 2009, at 7:39 AM, B Degnan wrote:

        > Do you have copies of any NTSC software for the Plus/4?
        > Bill
        >
      • Brian Cirulnick
        ... 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.
        Message 3 of 26 , Apr 8, 2009
        • 0 Attachment
          --- 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.
        • Brian Cirulnick
          ... Speaking of NTSC.. I used to use one of the Plus/4s at ... If I recall, the VIC-20 was genlockable and was used quite extensively as a cheap Khyron. I
          Message 4 of 26 , Apr 8, 2009
          • 0 Attachment
            --- In midatlanticretro@yahoogroups.com, Ray Sills <raysills@...> wrote:
            >
            Speaking of NTSC.. I used to use one of the Plus/4s at
            > work, as a way to generate a title "slate" for recording music cues
            > on to videotape. It worked quite well with the old Sony BVH-800 U-
            > Matic 3/4" machines. But that was because the machines were not the
            > least bit fussy about the quality of the video and the stability of
            > the time base. Once we switched to professional Beta format, the
            > Plus/4s didn't work properly. At that point, I got an Amiga (1000?)
            > (Also now at MARCH) with a gen-lock board, and that worked like a
            > champ.
            -------------------------

            If I recall, the VIC-20 was "genlockable" and was used quite extensively as a cheap Khyron. I also used a C-64 setup for use as a teleprompter because it easily integrated with existing NTSC equipment in a video studio.

            But yes, the Amiga was the champ when it came to the genlock. More Anime was fan-subtitled with the Amiga than probably any other system.

            Mark Tilden (of Robosapien fame) originally built his own subtitling equipment for his anime releases. Sean Farquarson and I used his Amiga 500 and Mike Ling's genlock, while I typed up the scripts on my 1000.

            Man, that was a lifetime ago....
          • Ray Sills
            Hi Brian: Nah... the VIC-20 and C-64 video output was NTSC, but there was no direct way to genlock to house black. In fact, I used a VIC-20 and a C-64 for
            Message 5 of 26 , Apr 8, 2009
            • 0 Attachment
              Hi Brian:

              Nah... the VIC-20 and C-64 video output was NTSC, but there was no
              direct way to genlock to house black. In fact, I used a VIC-20 and a
              C-64 for making title slates before using the Plus/4. The VIC-20 was
              actually handy due to the larger font.. easier to read at a distance
              from the CRT. The Plus/4 was better in the sense that I was able to
              create files that were easily appended to update projects.

              I also wrote a little app in basic that would "run a stopwatch" as
              the music was being recorded.. so although you didn't see TC per se..
              you could see how far along you were in the recording.

              73 de Ray

              On Apr 8, 2009, at 12:20 PM, Brian Cirulnick wrote:

              > --- In midatlanticretro@yahoogroups.com, Ray Sills <raysills@...>
              > wrote:
              >>
              > Speaking of NTSC.. I used to use one of the Plus/4s at
              >> work, as a way to generate a title "slate" for recording music cues
              >> on to videotape. It worked quite well with the old Sony BVH-800 U-
              >> Matic 3/4" machines. But that was because the machines were not the
              >> least bit fussy about the quality of the video and the stability of
              >> the time base. Once we switched to professional Beta format, the
              >> Plus/4s didn't work properly. At that point, I got an Amiga (1000?)
              >> (Also now at MARCH) with a gen-lock board, and that worked like a
              >> champ.
              > -------------------------
              >
              > If I recall, the VIC-20 was "genlockable" and was used quite
              > extensively as a cheap Khyron. I also used a C-64 setup for use as
              > a teleprompter because it easily integrated with existing NTSC
              > equipment in a video studio.
              >
              > But yes, the Amiga was the champ when it came to the genlock. More
              > Anime was fan-subtitled with the Amiga than probably any other system.
              >
              > Mark Tilden (of Robosapien fame) originally built his own
              > subtitling equipment for his anime releases. Sean Farquarson and I
              > used his Amiga 500 and Mike Ling's genlock, while I typed up the
              > scripts on my 1000.
              >
              > Man, that was a lifetime ago....
              >
              >
              >
              >
              > ------------------------------------
              >
              > Yahoo! Groups Links
              >
              >
              >
            • 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 6 of 26 , Apr 8, 2009
              • 0 Attachment

                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 7 of 26 , Apr 8, 2009
                • 0 Attachment
                  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 8 of 26 , Apr 8, 2009
                  • 0 Attachment
                    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 9 of 26 , Apr 11, 2009
                    • 0 Attachment
                      --- 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 10 of 26 , Apr 11, 2009
                      • 0 Attachment
                        ----- 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 11 of 26 , Apr 12, 2009
                        • 0 Attachment
                          --- 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 12 of 26 , Apr 12, 2009
                          • 0 Attachment
                            Hello new guy. Please introduce yourself, how you found us, etc.
                            > I use a simpler, more effective method .... JS
                            >
                          Your message has been successfully submitted and would be delivered to recipients shortly.