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[OB12] Re: DIY Display replacement

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  • o.fairhall
    Hi folks, I tried posting this yesterday, but it hasn t come through, for some reason. I ve copied the contents of the message here, and re-psoted... I can
    Message 1 of 36 , Sep 16, 2009
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      Hi folks, I tried posting this yesterday, but it hasn't come through, for some reason. I've copied the contents of the message here, and re-psoted...

      I can finally post a positive result for my display replacement.

      I am now using the following display:

      http://www.futurlec.com.au/LED/BLUE240X64LCD.jsp

      It is manufactured by Brilliant Crystal (sorry I don't have a model number).

      This is the display I first tried, but didn't originally manage to get working. The new display is almost a drop in replacement. I made a few minor changes to make this work:

      - I soldered a 20 pin (2 x 10) header to the LCD module PCB to connect the OB-12 display ribbon
      - I removed pin 20 from the header, which has to be open circuited for the contrast voltage to function correctly. One could also just cut the wire on the ribbon, if preferred
      - I desoldered a power resistor from the underside of the LCD module PCB, and fitted it on the top side instead. The resistor is quite thick, and gets in the way when bolting the module to the syth PCB. One may get away with just leaving it there, but I wanted it to fit better.
      -Desoldered the backlight LED supply wires from the original Varitronix OB-12 display, and soldered them on to the new display. I think it would probably also be fine just to use the +5V logic supply, which one could connect to the LEDs, though I didn't try this.

      The Brilliant Crystal display specifies a contrast voltage of 12V. This would normally be generated by using the +5V from the logic supply, and also providing a -7V LCD -ve drive voltage. However, I found the LCD to be extremely tolerant of the drive voltage, and works just fine with the OB-12's in built supplies. I tested the display with voltages from about 5 volts, to 15 volts (total drive voltage), and could see pretty much no difference in the display at all. The 10V from the OB-12 works just fine. After installation, I tried varying the contrast setting in the synth, and couldn't see any change in the display.

      When I first tested this display some time ago, I neglected to disconnect pin 20. In my memory, I thought I had tried that, and it hadn't made any difference. Looking back on it, I think I was probably interrupted, and forgot to complete the test. With pin 20 connected, no image will be visible.

      In the mean time, I had also tried the following display:

      https://www.eio.com/p-1114-orient-display-amg24064ar-m-b6wtdw-240x64-graphic-lcd.aspx

      This is an Orient Display AMG24064A. This is also compatible with the OB-12 display signals, but doesn't actually fit in the synth, as it is too thick. Also, unlike the Brilliant Crystal display, it really does require about 12V LCD drive. I'm not sure if the OB-12 is able to provide that level of -ve voltage from the display driver. My synth was set for the 10V of the Varitronix display when I was testing the replacement modules. I wasn't able to navigate to the contrast control when attempting to use this display. I did get it running using an opamp driver which I made, and operated from the OB-12's ±12V rails.

      Both displays look very similar, when operating, and are bright and clear, and suitably blue for the OB-12. I will try to post some photos in the near future. Right now, I don't have a camera available. I will also upload a brief document to the files section on the matter, for anyone else who may go looking for the info.

      I'm pretty happy to finally be able to use the synth, which has been broken since I bought it on eBay. Unfortunately, I have lost some of the button caps in the mean time. I thought I had placed them in my box of synth parts, but can't find them now. I have moved house since then, and have no idea where the things have gone. To me, they look similar to the Waldorf Q buttons (just judging from photos), which I'm hoping may help me to find some replacements.

      Next step is to update my software, and program some patches. I'm not particularly impressed with what is currently in the synth.

      Cheers,

      Oli
    • synthiemoogin
      Thanks for the update. I tried to use the one mentioned on the web as a blue SY77 replacement display type EW50340BMW from http://www.zinguy.com/lcdpage.htm.
      Message 36 of 36 , Sep 30, 2009
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        Thanks for the update. I tried to use the one mentioned on the web as a blue SY77 replacement display type EW50340BMW from http://www.zinguy.com/lcdpage.htm. When I bought them a few years ago they were around $20 but have now gone up. I did not have success initially and did leave pin 20 open but I will try again after hearing you have been successful. I think these LCDs have the same pin-outs as the one you used.

        --- In FriendsofOB12@yahoogroups.com, "o.fairhall" <o.fairhall@...> wrote:
        >
        > Hi folks, I tried posting this yesterday, but it hasn't come through, for some reason. I've copied the contents of the message here, and re-psoted...
        >
        > I can finally post a positive result for my display replacement.
        >
        > I am now using the following display:
        >
        > http://www.futurlec.com.au/LED/BLUE240X64LCD.jsp
        >
        > It is manufactured by Brilliant Crystal (sorry I don't have a model number).
        >
        > This is the display I first tried, but didn't originally manage to get working. The new display is almost a drop in replacement. I made a few minor changes to make this work:
        >
        > - I soldered a 20 pin (2 x 10) header to the LCD module PCB to connect the OB-12 display ribbon
        > - I removed pin 20 from the header, which has to be open circuited for the contrast voltage to function correctly. One could also just cut the wire on the ribbon, if preferred
        > - I desoldered a power resistor from the underside of the LCD module PCB, and fitted it on the top side instead. The resistor is quite thick, and gets in the way when bolting the module to the syth PCB. One may get away with just leaving it there, but I wanted it to fit better.
        > -Desoldered the backlight LED supply wires from the original Varitronix OB-12 display, and soldered them on to the new display. I think it would probably also be fine just to use the +5V logic supply, which one could connect to the LEDs, though I didn't try this.
        >
        > The Brilliant Crystal display specifies a contrast voltage of 12V. This would normally be generated by using the +5V from the logic supply, and also providing a -7V LCD -ve drive voltage. However, I found the LCD to be extremely tolerant of the drive voltage, and works just fine with the OB-12's in built supplies. I tested the display with voltages from about 5 volts, to 15 volts (total drive voltage), and could see pretty much no difference in the display at all. The 10V from the OB-12 works just fine. After installation, I tried varying the contrast setting in the synth, and couldn't see any change in the display.
        >
        > When I first tested this display some time ago, I neglected to disconnect pin 20. In my memory, I thought I had tried that, and it hadn't made any difference. Looking back on it, I think I was probably interrupted, and forgot to complete the test. With pin 20 connected, no image will be visible.
        >
        > In the mean time, I had also tried the following display:
        >
        > https://www.eio.com/p-1114-orient-display-amg24064ar-m-b6wtdw-240x64-graphic-lcd.aspx
        >
        > This is an Orient Display AMG24064A. This is also compatible with the OB-12 display signals, but doesn't actually fit in the synth, as it is too thick. Also, unlike the Brilliant Crystal display, it really does require about 12V LCD drive. I'm not sure if the OB-12 is able to provide that level of -ve voltage from the display driver. My synth was set for the 10V of the Varitronix display when I was testing the replacement modules. I wasn't able to navigate to the contrast control when attempting to use this display. I did get it running using an opamp driver which I made, and operated from the OB-12's ±12V rails.
        >
        > Both displays look very similar, when operating, and are bright and clear, and suitably blue for the OB-12. I will try to post some photos in the near future. Right now, I don't have a camera available. I will also upload a brief document to the files section on the matter, for anyone else who may go looking for the info.
        >
        > I'm pretty happy to finally be able to use the synth, which has been broken since I bought it on eBay. Unfortunately, I have lost some of the button caps in the mean time. I thought I had placed them in my box of synth parts, but can't find them now. I have moved house since then, and have no idea where the things have gone. To me, they look similar to the Waldorf Q buttons (just judging from photos), which I'm hoping may help me to find some replacements.
        >
        > Next step is to update my software, and program some patches. I'm not particularly impressed with what is currently in the synth.
        >
        > Cheers,
        >
        > Oli
        >
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