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Vip Video

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  • chucko205
    My Cosmac Vip signals the sound and Q light ok but no video, tried the video chip in a studio 2 and it works fine, signal out is above 0.5(appx 1.0) volts,
    Message 1 of 20 , May 12, 2013
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      My Cosmac Vip signals the sound and Q light ok but no video, tried the video chip in a studio 2 and it works fine, signal out is above 0.5(appx 1.0) volts, sending to comp input on new led tv, could tv be a problem?
    • joshbensadon
      ... I m a little confused by the steps taken. When you say the chip works fine in the Studio 2, is it connected to the new led tv ? Is that the signal output
      Message 2 of 20 , May 12, 2013
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        --- In rcacosmac@yahoogroups.com, "chucko205" <chucko205@...> wrote:
        >
        > My Cosmac Vip signals the sound and Q light ok but no video, tried the video chip in a studio 2 and it works fine, signal out is above 0.5(appx 1.0) volts, sending to comp input on new led tv, could tv be a problem?
        >

        I'm a little confused by the steps taken.

        When you say the chip works fine in the Studio 2, is it connected to the "new led tv"? Is that the signal output you are measuring at .5 or 1.0 volts? Or is this output voltage from the VIP?

        And which is it, .5V or 1.0V?

        :)J
      • chucko205
        The RCA Vip and Rca Studio 2 was connected to same LED TV ( A 10” Haier) Both 1861 video chips were tried in each system , both worked in the Studio 2 none
        Message 3 of 20 , May 12, 2013
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          The RCA Vip and Rca Studio 2 was connected to same LED TV ( A 10” Haier) Both 1861 video chips were tried in each system , both worked in the Studio 2 none worked in the Vip. The signals in the Vip were 4 volts on pin 6, 0.3 volts on pin 7 of the 1861 chip  and 215 MV on the output. TPA and TPB both are pulsing and clock frequency are correct 3.2 Mhz and 1.7 Mhz. Vip ram is 2- 2114 chips.
          Power light  is lit when on.
          Q light and tone is on when switch is set to run and c key is being pressed. when key is released both go off both go on when key is pressed, again and off when released. Smile
           
          Sent: Sunday, May 12, 2013 10:56 AM
          Subject: [rcacosmac] Re: Vip Video
           
           



          --- In mailto:rcacosmac%40yahoogroups.com, "chucko205" <chucko205@...> wrote:

          >
          > My Cosmac Vip signals
          the sound and Q light ok but no video, tried the video chip in a studio 2 and it works fine, signal out is above 0.5(appx 1.0) volts, sending to comp input on new led tv, could tv be a problem?
          >

          I'm a little confused by the steps taken.

          When you say the chip works fine in the Studio 2, is it connected to the "new led tv"? Is that the signal output you are measuring at .5 or 1.0 volts? Or is this output voltage from the VIP?

          And which is it, .5V or 1.0V?

          :)J

        • Josh Bensadon
          Hi Chuck, I was going to check the output on my VELF, but I installed some buffer chip on the video output.  I didn t remember why until I checked my VIP. 
          Message 4 of 20 , May 12, 2013
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            Hi Chuck,

            I was going to check the output on my VELF, but I installed some buffer chip on the video output.  I didn't remember why until I checked my VIP.  Checking my VIP, I have 3.7V on pin 6, 0.37 on pin 7 and 100mV at the output (while connected to a monitor), 
            3.8V, 0.51 and 700mV when NOT connected to a monitor.

            The monitor I'm using is one of those RCA 12" security monitors, with the 75ohm terminator.

            These voltages make sense, the Sync line should be high most of the time, only drops to provide the sync pulses which are "blacker than black".  The Dot line only goes high where it needs to light the screen, I would expect it to be a little higher in voltage, but that depends on how much of the screen it needs to light. Scoping this line, it only has about a 20% duty cycle.

            The video output is very poor on from my VIP.  My monitor does not sync properly with it.  This is the reason why on my VELF, that I used an extra buffer chip to drive the Sync and Dot outputs with more range.

            Doesn't the Studio 2 have an RF modulated output?  Perhaps this is why it works fine on your TV, the RF Modulator has no problem (and was designed for these low levels).

            I am going to guess that your initial guess of it being the TV is correct.

            Perhaps you can try connecting your VIP to an RF Modulator and take that to your TV?

            :)J


            --- On Sun, 5/12/13, chucko205 <chucko205@...> wrote:

            From: chucko205 <chucko205@...>
            Subject: Re: [rcacosmac] Re: Vip Video
            To: rcacosmac@yahoogroups.com
            Received: Sunday, May 12, 2013, 6:26 PM

             

            The RCA Vip and Rca Studio 2 was connected to same LED TV ( A 10” Haier) Both 1861 video chips were tried in each system , both worked in the Studio 2 none worked in the Vip. The signals in the Vip were 4 volts on pin 6, 0.3 volts on pin 7 of the 1861 chip  and 215 MV on the output. TPA and TPB both are pulsing and clock frequency are correct 3.2 Mhz and 1.7 Mhz. Vip ram is 2- 2114 chips.
            Power light  is lit when on.
            Q light and tone is on when switch is set to run and c key is being pressed. when key is released both go off both go on when key is pressed, again and off when released. Smile
             
            Sent: Sunday, May 12, 2013 10:56 AM
            Subject: [rcacosmac] Re: Vip Video
             
             



            --- In mailto:rcacosmac%40yahoogroups.com, "chucko205" <chucko205@...> wrote:
            >
            > My Cosmac Vip signals the sound and Q light ok but no video, tried the video chip in a studio 2 and it works fine, signal out is above 0.5(appx 1.0) volts, sending to comp input on new led tv, could tv be a problem?
            >

            I'm a little confused by the steps taken.

            When you say the chip works fine in the Studio 2, is it connected to the "new led tv"? Is that the signal output you are measuring at .5 or 1.0 volts? Or is this output voltage from the VIP?

            And which is it, .5V or 1.0V?

            :)J

          • chucko205
            The TV has a 75 ohm ant input and a RCA comp video input.I tried the Vip using a RF modulator to the 75 ohm ant input, nothing, I connected direct to the RCA
            Message 5 of 20 , May 13, 2013
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              The TV has a 75 ohm ant input and a RCA comp video input.I tried the Vip using a RF modulator to the 75 ohm ant input, nothing, I connected direct to the RCA input,nothing. I dug out a old CRT Ademco video monitor with 75 ohm video input, works great!! Question, How to modify the Vip video output to work with a newer RCA comp video input? Would a 2N2222 transistor give me enough signal boost? You mentioned a buffer chip?
              Thanks

              --- In rcacosmac@yahoogroups.com, Josh Bensadon <joshbensadon@...> wrote:
              >
              > Hi Chuck,
              >
              > I was going to check the output on my VELF, but I installed some buffer chip on the video output.  I didn't remember why until I checked my VIP.  Checking my VIP, I have 3.7V on pin 6, 0.37 on pin 7 and 100mV at the output (while connected to a monitor), 
              > 3.8V, 0.51 and 700mV when NOT connected to a monitor.
              >
              > The monitor I'm using is one of those RCA 12" security monitors, with the 75ohm terminator.
              >
              > These voltages make sense, the Sync line should be high most of the time, only drops to provide the sync pulses which are "blacker than black".  The Dot line only goes high where it needs to light the screen, I would expect it to be a little higher in voltage, but that depends on how much of the screen it needs to light. Scoping this line, it only has about a 20% duty cycle.
              >
              > The video output is very poor on from my VIP.  My monitor does not sync properly with it.  This is the reason why on my VELF, that I used an extra buffer chip to drive the Sync and Dot outputs with more range.
              >
              > Doesn't the Studio 2 have an RF modulated output?  Perhaps this is why it works fine on your TV, the RF Modulator has no problem (and was designed for these low levels).
              >
              > I am going to guess that your initial guess of it being the TV is correct.
              >
              > Perhaps you can try connecting your VIP to an RF Modulator and take that to your TV?
              >
              > :)J
              >
              >
              > --- On Sun, 5/12/13, chucko205 <chucko205@...> wrote:
              >
              > From: chucko205 <chucko205@...>
              > Subject: Re: [rcacosmac] Re: Vip Video
              > To: rcacosmac@yahoogroups.com
              > Received: Sunday, May 12, 2013, 6:26 PM
              >
              >
              >
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              >  
              >
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              >
              >
              > The RCA Vip and Rca Studio 2 was connected to same LED TV ( A 10” Haier)
              > Both 1861 video chips were tried in each system , both worked in the Studio 2
              > none worked in the Vip. The signals in the Vip were 4 volts on pin 6, 0.3 volts
              > on pin 7 of the 1861 chip  and 215 MV on the output. TPA and TPB both are
              > pulsing and clock frequency are correct 3.2 Mhz and 1.7 Mhz. Vip ram is 2- 2114
              > chips.
              > Power light  is lit when on.
              > Q light and tone is on when switch is set to run and c key is being
              > pressed. when key is released both go off both go on when key is pressed, again
              > and off when released.
              >
              >
              >  
              >
              > From: joshbensadon
              > Sent: Sunday, May 12, 2013 10:56 AM
              > To: rcacosmac@yahoogroups.com
              > Subject: [rcacosmac] Re: Vip Video
              >  
              >  
              >
              >
              >
              > --- In mailto:rcacosmac%40yahoogroups.com,
              > "chucko205" <chucko205@> wrote:
              > >
              > > My Cosmac Vip signals
              > the sound and Q light ok but no video, tried the video chip in a studio 2 and it
              > works fine, signal out is above 0.5(appx 1.0) volts, sending to comp input on
              > new led tv, could tv be a problem?
              > >
              >
              > I'm a little confused by the
              > steps taken.
              >
              > When you say the chip works fine in the Studio 2, is it
              > connected to the "new led tv"? Is that the signal output you are measuring at .5
              > or 1.0 volts? Or is this output voltage from the VIP?
              >
              > And which is it,
              > .5V or 1.0V?
              >
              > :)J
              >
            • Josh Bensadon
              Hi Chuck, I added a 4050 buffer chip to boost the digital output swing of the Sync and Spot line. Please see my (updated) schematic on the VELF in the files
              Message 6 of 20 , May 14, 2013
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                Hi Chuck,

                I added a 4050 buffer chip to boost the digital output swing of the Sync and Spot line.

                Please see my (updated) schematic on the VELF in the files section of the COSMACELF forum.  Look in the folder Member-Josh Bensadon

                Cheers,
                Josh


                --- On Mon, 5/13/13, chucko205 <chucko205@...> wrote:

                From: chucko205 <chucko205@...>
                Subject: [rcacosmac] Re: Vip Video
                To: rcacosmac@yahoogroups.com
                Received: Monday, May 13, 2013, 9:56 PM

                 



                The TV has a 75 ohm ant input and a RCA comp video input.I tried the Vip using a RF modulator to the 75 ohm ant input, nothing, I connected direct to the RCA input,nothing. I dug out a old CRT Ademco video monitor with 75 ohm video input, works great!! Question, How to modify the Vip video output to work with a newer RCA comp video input? Would a 2N2222 transistor give me enough signal boost? You mentioned a buffer chip?
                Thanks

                --- In rcacosmac@yahoogroups.com, Josh Bensadon <joshbensadon@...> wrote:
                >
                > Hi Chuck,
                >
                > I was going to check the output on my VELF, but I installed some buffer chip on the video output.  I didn't remember why until I checked my VIP.  Checking my VIP, I have 3.7V on pin 6, 0.37 on pin 7 and 100mV at the output (while connected to a monitor), 
                > 3.8V, 0.51 and 700mV when NOT connected to a monitor.
                >
                > The monitor I'm using is one of those RCA 12" security monitors, with the 75ohm terminator.
                >
                > These voltages make sense, the Sync line should be high most of the time, only drops to provide the sync pulses which are "blacker than black".  The Dot line only goes high where it needs to light the screen, I would expect it to be a little higher in voltage, but that depends on how much of the screen it needs to light. Scoping this line, it only has about a 20% duty cycle.
                >
                > The video output is very poor on from my VIP.  My monitor does not sync properly with it.  This is the reason why on my VELF, that I used an extra buffer chip to drive the Sync and Dot outputs with more range.
                >
                > Doesn't the Studio 2 have an RF modulated output?  Perhaps this is why it works fine on your TV, the RF Modulator has no problem (and was designed for these low levels).
                >
                > I am going to guess that your initial guess of it being the TV is correct.
                >
                > Perhaps you can try connecting your VIP to an RF Modulator and take that to your TV?
                >
                > :)J
                >
                >
                > --- On Sun, 5/12/13, chucko205 <chucko205@...> wrote:
                >
                > From: chucko205 <chucko205@...>
                > Subject: Re: [rcacosmac] Re: Vip Video
                > To: rcacosmac@yahoogroups.com
                > Received: Sunday, May 12, 2013, 6:26 PM
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >  
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                > The RCA Vip and Rca Studio 2 was connected to same LED TV ( A 10” Haier)
                > Both 1861 video chips were tried in each system , both worked in the Studio 2
                > none worked in the Vip. The signals in the Vip were 4 volts on pin 6, 0.3 volts
                > on pin 7 of the 1861 chip  and 215 MV on the output. TPA and TPB both are
                > pulsing and clock frequency are correct 3.2 Mhz and 1.7 Mhz. Vip ram is 2- 2114
                > chips.
                > Power light  is lit when on.
                > Q light and tone is on when switch is set to run and c key is being
                > pressed. when key is released both go off both go on when key is pressed, again
                > and off when released.
                >
                >
                >  
                >
                > From: joshbensadon
                > Sent: Sunday, May 12, 2013 10:56 AM
                > To: rcacosmac@yahoogroups.com
                > Subject: [rcacosmac] Re: Vip Video
                >  
                >  
                >
                >
                >
                > --- In mailto:rcacosmac%40yahoogroups.com,
                > "chucko205" <chucko205@> wrote:
                > >
                > > My Cosmac Vip signals
                > the sound and Q light ok but no video, tried the video chip in a studio 2 and it
                > works fine, signal out is above 0.5(appx 1.0) volts, sending to comp input on
                > new led tv, could tv be a problem?
                > >
                >
                > I'm a little confused by the
                > steps taken.
                >
                > When you say the chip works fine in the Studio 2, is it
                > connected to the "new led tv"? Is that the signal output you are measuring at .5
                > or 1.0 volts? Or is this output voltage from the VIP?
                >
                > And which is it,
                > .5V or 1.0V?
                >
                > :)J
                >

              • ekeefe8051
                Hello, Maybe this will help, it is the amplifier used on the Quest super elf. http://www.avionline.com/1861_amp.jpg Good luck, ED
                Message 7 of 20 , May 14, 2013
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                  Hello,

                  Maybe this will help, it is the amplifier used on the Quest super elf.

                  http://www.avionline.com/1861_amp.jpg

                  Good luck,

                  ED

                  --- In rcacosmac@yahoogroups.com, "chucko205" <chucko205@...> wrote:
                  >
                  > My Cosmac Vip signals the sound and Q light ok but no video, tried the video chip in a studio 2 and it works fine, signal out is above 0.5(appx 1.0) volts, sending to comp input on new led tv, could tv be a problem?
                  >
                • Josh Bensadon
                  Hi Ed, That looks great!  It s even simpler than my 4050 buffer chip.   Thanks, ... From: ekeefe8051 Subject: [rcacosmac] Re: Vip
                  Message 8 of 20 , May 14, 2013
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                    Hi Ed,

                    That looks great!  It's even simpler than my 4050 buffer chip.
                     
                    Thanks,
                    :)J


                    --- On Tue, 5/14/13, ekeefe8051 <ekeefe8051@...> wrote:

                    From: ekeefe8051 <ekeefe8051@...>
                    Subject: [rcacosmac] Re: Vip Video
                    To: rcacosmac@yahoogroups.com
                    Received: Tuesday, May 14, 2013, 2:18 PM

                     

                    Hello,

                    Maybe this will help, it is the amplifier used on the Quest super elf.

                    http://www.avionline.com/1861_amp.jpg

                    Good luck,

                    ED

                    --- In rcacosmac@yahoogroups.com, "chucko205" <chucko205@...> wrote:
                    >
                    > My Cosmac Vip signals the sound and Q light ok but no video, tried the video chip in a studio 2 and it works fine, signal out is above 0.5(appx 1.0) volts, sending to comp input on new led tv, could tv be a problem?
                    >

                  • chucko205
                    Thank you all for the help! I used Ed s direction to the amplifer on the Quest super ELf. I used 2.2k Resistor for R11 and 47 Ohm for R3, Modified the vip and
                    Message 9 of 20 , May 15, 2013
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                      Thank you all for the help!
                      I used Ed's direction to the amplifer on the Quest super ELf.
                      I used 2.2k Resistor for R11 and 47 Ohm for R3, Modified the vip and built circuit on top of board. Display is rock solid. I have uploaded pictures in the photo's section under Vip Video. Now to fill out and complete the board!:)
                    • joshbensadon
                      Great to hear the good news. I also like Ed s suggestion with the Super Elf way. It beats adding a whole chip to buffer the video. When I get a chance to,
                      Message 10 of 20 , May 15, 2013
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                        Great to hear the good news.

                        I also like Ed's suggestion with the Super Elf way. It beats adding a whole chip to buffer the video. When I get a chance to, I'm going to redo my video output with the same circuit!

                        :)J


                        --- In rcacosmac@yahoogroups.com, "chucko205" <chucko205@...> wrote:
                        >
                        > Thank you all for the help!
                        > I used Ed's direction to the amplifer on the Quest super ELf.
                        > I used 2.2k Resistor for R11 and 47 Ohm for R3, Modified the vip and built circuit on top of board. Display is rock solid. I have uploaded pictures in the photo's section under Vip Video. Now to fill out and complete the board!:)
                        >
                      • ekeefe8051
                        Hello, @chucko205 I m glad it worked for you. If you have any questions, just ask. @joshbensadon Thanks. If I can help, just ask. By the way, did you get my
                        Message 11 of 20 , May 16, 2013
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                          Hello,

                          @chucko205
                          I'm glad it worked for you. If you have any questions, just ask.

                          @joshbensadon
                          Thanks. If I can help, just ask. By the way, did you get my e-mail about making a PCB to build your VELF? I will send it again if not.

                          ED

                          --- In rcacosmac@yahoogroups.com, "chucko205" <chucko205@...> wrote:
                          >
                          > Thank you all for the help!
                          > I used Ed's direction to the amplifer on the Quest super ELf.
                          > I used 2.2k Resistor for R11 and 47 Ohm for R3, Modified the vip and built circuit on top of board. Display is rock solid. I have uploaded pictures in the photo's section under Vip Video. Now to fill out and complete the board!:)
                          >
                        • joshbensadon
                          Hi Ed, No, I didn t get your email. A PCB for the VELF, very nice! Can it include the Quest ELF s Video Buffer circuit just covered? If I get a chance, I
                          Message 12 of 20 , May 16, 2013
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                            Hi Ed,

                            No, I didn't get your email. A PCB for the VELF, very nice! Can it include the Quest ELF's "Video Buffer" circuit just covered?

                            If I get a chance, I can add more Chip-8 programs to the EPROM.

                            :)J



                            --- In rcacosmac@yahoogroups.com, "ekeefe8051" <ekeefe8051@...> wrote:
                            >
                            > Hello,
                            >
                            > @chucko205
                            > I'm glad it worked for you. If you have any questions, just ask.
                            >
                            > @joshbensadon
                            > Thanks. If I can help, just ask. By the way, did you get my e-mail about making a PCB to build your VELF? I will send it again if not.
                            >
                            > ED
                            >
                            > --- In rcacosmac@yahoogroups.com, "chucko205" <chucko205@> wrote:
                            > >
                            > > Thank you all for the help!
                            > > I used Ed's direction to the amplifer on the Quest super ELf.
                            > > I used 2.2k Resistor for R11 and 47 Ohm for R3, Modified the vip and built circuit on top of board. Display is rock solid. I have uploaded pictures in the photo's section under Vip Video. Now to fill out and complete the board!:)
                            > >
                            >
                          • DougCrawford
                            ... This was an interesting thread; thanks everyone for the participation. My VIP had the same issue; I went thru a few monitors till I found one that would
                            Message 13 of 20 , May 17, 2013
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                              --- In rcacosmac@yahoogroups.com, "chucko205" <chucko205@...> wrote:
                              >
                              > My Cosmac Vip signals the sound and Q light ok but no video, tried the video chip in a studio 2 and it works fine, signal out is above 0.5(appx 1.0) volts, sending to comp input on new led tv, could tv be a problem?
                              >


                              This was an interesting thread; thanks everyone for the participation. My VIP had the same issue; I went thru a few monitors till I found
                              one that would sync.

                              I have a televideo 920 termininal sans main board and was thinking
                              of putting the VIP into the terminal... hooking up the video using a sync separator to the televideo signals. Didn't get to it (yet?)
                              but its comforting to know I can improve the video in this way... I didn't know if it was a level or timing issue. Nows I (we) do!
                            • joshbensadon
                              Hi Doug, The Televideo 920 is a nice looking terminal, it would be a shame to not use it as a sort of Super VIP . You just need to add some keyboard
                              Message 14 of 20 , May 17, 2013
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                                Hi Doug,

                                The Televideo 920 is a nice looking terminal, it would be a shame to not use it as a sort of "Super VIP". You just need to add some keyboard interface and put some ELF Basic into ROM :)
                                Lot's of good projects... not enough time, I'm facing the same dilemma here.
                                I think the 1881 chip makes a good sync separator, but if you want to do it using only 74LS chips, I built a circuit that does just that... I'll just need to draw it for you as it's still on the bread board.

                                :)J


                                --- In rcacosmac@yahoogroups.com, "DougCrawford" <touchetek@...> wrote:
                                >
                                >
                                >
                                > --- In rcacosmac@yahoogroups.com, "chucko205" <chucko205@> wrote:
                                > >
                                > > My Cosmac Vip signals the sound and Q light ok but no video, tried the video chip in a studio 2 and it works fine, signal out is above 0.5(appx 1.0) volts, sending to comp input on new led tv, could tv be a problem?
                                > >
                                >
                                >
                                > This was an interesting thread; thanks everyone for the participation. My VIP had the same issue; I went thru a few monitors till I found
                                > one that would sync.
                                >
                                > I have a televideo 920 termininal sans main board and was thinking
                                > of putting the VIP into the terminal... hooking up the video using a sync separator to the televideo signals. Didn't get to it (yet?)
                                > but its comforting to know I can improve the video in this way... I didn't know if it was a level or timing issue. Nows I (we) do!
                                >
                              • DougCrawford
                                ... Well the terminal had p.s. issues so I let it go at a swap meet. I ll look for something else to make Super VIP PC out of. I still think its a good idea.
                                Message 15 of 20 , May 20, 2013
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                                  --- In rcacosmac@yahoogroups.com, "joshbensadon" <joshbensadon@...> wrote:
                                  >
                                  > Hi Doug,
                                  >
                                  > The Televideo 920 is a nice looking terminal, it would be a shame to not use it as a sort of "Super VIP". You just need to add some keyboard interface and put some ELF Basic into ROM :)
                                  > Lot's of good projects... not enough time, I'm facing the same dilemma here.
                                  > I think the 1881 chip makes a good sync separator, but if you want to do it using only 74LS chips, I built a circuit that does just that... I'll just need to draw it for you as it's still on the bread board.
                                  >
                                  > :)J
                                  >
                                  >
                                  > --- In rcacosmac@yahoogroups.com, "DougCrawford" <touchetek@> wrote:
                                  > >
                                  > >
                                  > >
                                  > > --- In rcacosmac@yahoogroups.com, "chucko205" <chucko205@> wrote:
                                  > > >
                                  > > > My Cosmac Vip signals the sound and Q light ok but no video, tried the video chip in a studio 2 and it works fine, signal out is above 0.5(appx 1.0) volts, sending to comp input on new led tv, could tv be a problem?
                                  > > >
                                  > >
                                  > >
                                  > > This was an interesting thread; thanks everyone for the participation. My VIP had the same issue; I went thru a few monitors till I found
                                  > > one that would sync.
                                  > >
                                  > > I have a televideo 920 termininal sans main board and was thinking
                                  > > of putting the VIP into the terminal... hooking up the video using a sync separator to the televideo signals. Didn't get to it (yet?)
                                  > > but its comforting to know I can improve the video in this way... I didn't know if it was a level or timing issue. Nows I (we) do!
                                  > >
                                  >

                                  Well the terminal had p.s. issues so I let it go at a swap meet.
                                  I'll look for something else to make Super VIP PC out of.
                                  I still think its a good idea.
                                • DougCrawford
                                  My VIP had sync issues also with all my available monitors but one apparently very forgiving professional video monitor. I did the modification with the
                                  Message 16 of 20 , Jul 24, 2013
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                                    My VIP had sync issues also with all my available monitors but one apparently very forgiving professional video monitor.
                                    I did the modification with the transistor and it now syncs with an LCD monitor which previously did not work.

                                    I used an MPS222A from Radio Shack instead of a 2N2222 because it was available. On the output let I also substituted 47 ohm and 220 ohm as close enough.

                                    Here's photos of the result and the mod, done topside fairly cleanly.
                                    http://imgur.com/a/0VQ4i/all

                                    Amplitude of the sync pulse is about 1v.

                                    QUESTION: What resister value change would bring reduce the amplitude slightly?

                                    Thanks!
                                  • joshbensadon
                                    Hi Doug, That looks really good. Nice work! If you increase the resistor between Sync and the Transistor base, that should decrease the sync and increase
                                    Message 17 of 20 , Jul 24, 2013
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                                      Hi Doug,

                                      That looks really good. Nice work!

                                      If you increase the resistor between Sync and the Transistor base, that should decrease the "sync" and increase the "video". I'm partially guessing at the ciruit but it looks like a balance sort of thing. The 10K pull up gives the whole base circuit a general bias but the Spot (video) and /Sync outputs play off each other to make 3 voltage steps (White, Black, Sync). So changing either the Spot or Sync resistor will move that middle voltage (black), essentially changing the ratio of Video to Sync. To attenuate the whole signal, change the output resistors, 30/200, or what you used 47/220.

                                      Sometimes, it pays to just use trimmer pot(s).

                                      :)J


                                      --- In rcacosmac@yahoogroups.com, "DougCrawford" <touchetek@...> wrote:
                                      >
                                      > My VIP had sync issues also with all my available monitors but one apparently very forgiving professional video monitor.
                                      > I did the modification with the transistor and it now syncs with an LCD monitor which previously did not work.
                                      >
                                      > I used an MPS222A from Radio Shack instead of a 2N2222 because it was available. On the output let I also substituted 47 ohm and 220 ohm as close enough.
                                      >
                                      > Here's photos of the result and the mod, done topside fairly cleanly.
                                      > http://imgur.com/a/0VQ4i/all
                                      >
                                      > Amplitude of the sync pulse is about 1v.
                                      >
                                      > QUESTION: What resister value change would bring reduce the amplitude slightly?
                                      >
                                      > Thanks!
                                      >
                                    • DougCrawford
                                      Thanks very much for the analysis Josh! It was a good puzzle figuring out how to build this on top so that it was physically stable and free of shorting
                                      Message 18 of 20 , Jul 25, 2013
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                                        Thanks very much for the analysis Josh!
                                        It was a good puzzle figuring out how to build this
                                        on top so that it was physically stable and free of
                                        shorting possibilities. I was pretty happy with
                                        the result.

                                        Yes, when I looked at the result on the scope and thought
                                        about bringing the amplitude down a touch I thought
                                        wow a few trimmer pots would have been smart :)

                                        For those who might follow our steps here,
                                        the original circuit measured .5v sync without a load.
                                        That seemed to be in line with composite specifications.
                                        But when I connected the LCD monitor, the signal went to about nothing. So for me, I was looking for beefier drive not more amplitude. With the transistor, the sync pulse was 1v under load...
                                        looks like I got both, hence the thought of having some
                                        control over the amplitudes.

                                        I think I will leave it alone for now though. There is only
                                        a little bit of what looks like overdrive... some vertical line
                                        artifacts across the screen at regular intervals. Not
                                        enough to really bother me and it might be the monitor's problem.

                                        --- In rcacosmac@yahoogroups.com, "joshbensadon" <joshbensadon@...> wrote:
                                        >
                                        > Hi Doug,
                                        >
                                        > That looks really good. Nice work!
                                        >
                                        > If you increase the resistor between Sync and the Transistor base, that should decrease the "sync" and increase the "video". I'm partially guessing at the ciruit but it looks like a balance sort of thing. The 10K pull up gives the whole base circuit a general bias but the Spot (video) and /Sync outputs play off each other to make 3 voltage steps (White, Black, Sync). So changing either the Spot or Sync resistor will move that middle voltage (black), essentially changing the ratio of Video to Sync. To attenuate the whole signal, change the output resistors, 30/200, or what you used 47/220.
                                        >
                                        > Sometimes, it pays to just use trimmer pot(s).
                                        >
                                        > :)J
                                        >
                                        >
                                        > --- In rcacosmac@yahoogroups.com, "DougCrawford" <touchetek@> wrote:
                                        > >
                                        > > My VIP had sync issues also with all my available monitors but one apparently very forgiving professional video monitor.
                                        > > I did the modification with the transistor and it now syncs with an LCD monitor which previously did not work.
                                        > >
                                        > > I used an MPS222A from Radio Shack instead of a 2N2222 because it was available. On the output let I also substituted 47 ohm and 220 ohm as close enough.
                                        > >
                                        > > Here's photos of the result and the mod, done topside fairly cleanly.
                                        > > http://imgur.com/a/0VQ4i/all
                                        > >
                                        > > Amplitude of the sync pulse is about 1v.
                                        > >
                                        > > QUESTION: What resister value change would bring reduce the amplitude slightly?
                                        > >
                                        > > Thanks!
                                        > >
                                        >
                                      • joshbensadon
                                        ... Yes, it looks very good sitting on top of the PCB there. If you have some flux remover or 99% alcohol, you can clean just that area with a Q-Tip. ... I
                                        Message 19 of 20 , Jul 26, 2013
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                                          --- In rcacosmac@yahoogroups.com, "DougCrawford" <touchetek@...> wrote:
                                          >
                                          >
                                          > Thanks very much for the analysis Josh!
                                          > It was a good puzzle figuring out how to build this
                                          > on top so that it was physically stable and free of
                                          > shorting possibilities. I was pretty happy with
                                          > the result.


                                          Yes, it looks very good sitting on top of the PCB there.
                                          If you have some flux remover or 99% alcohol, you can clean just that area with a Q-Tip.


                                          > I think I will leave it alone for now though. There is only
                                          > a little bit of what looks like overdrive... some vertical line
                                          > artifacts across the screen at regular intervals. Not
                                          > enough to really bother me and it might be the monitor's problem.


                                          I agree, "Working" is good enough. Sometimes, I spend hours tracking down little glitches, and later regret wasting so much time when there are so many other fun projects that need attention.

                                          :)J
                                        • DougCrawford
                                          ... Yes as I looked back at the pics it occurred to me how nasty that flux looked. All done, thanks!
                                          Message 20 of 20 , Jul 27, 2013
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                                            >If you have some flux remover or 99% alcohol, you can clean just that area with a Q-Tip.

                                            Yes as I looked back at the pics it occurred to me how nasty that flux looked. All done, thanks!

                                            --- In rcacosmac@yahoogroups.com, "joshbensadon" <joshbensadon@...> wrote:
                                            >
                                            > --- In rcacosmac@yahoogroups.com, "DougCrawford" <touchetek@> wrote:
                                            > >
                                            > >
                                            > > Thanks very much for the analysis Josh!
                                            > > It was a good puzzle figuring out how to build this
                                            > > on top so that it was physically stable and free of
                                            > > shorting possibilities. I was pretty happy with
                                            > > the result.
                                            >
                                            >
                                            > Yes, it looks very good sitting on top of the PCB there.
                                            > If you have some flux remover or 99% alcohol, you can clean just that area with a Q-Tip.
                                            >
                                            >
                                            > > I think I will leave it alone for now though. There is only
                                            > > a little bit of what looks like overdrive... some vertical line
                                            > > artifacts across the screen at regular intervals. Not
                                            > > enough to really bother me and it might be the monitor's problem.
                                            >
                                            >
                                            > I agree, "Working" is good enough. Sometimes, I spend hours tracking down little glitches, and later regret wasting so much time when there are so many other fun projects that need attention.
                                            >
                                            > :)J
                                            >
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