[Coco] Coco monitors 1084s-xx ?

[William Haywood]

 Thanks that is what I was looking for!
On Mar 28, 2014, at 11:45 PM, mike delyea <mdelyea at gmail.com> wrote:

> None of them will work.  You need to wire in a 74ls02 to change the
> horiz/vert signal.  I have done this myself because nobody seemed to know
> how at the time.  I spent a lot of time tracking down pinouts for Amiga
> monitors and the signals on each wire.  I posted instructions and a wiring
> diagram on coco3.com but who knows if its still there.  Searched and found.
> 
> I picked up an old Amiga 1080 monitor for next to nothing and
> 
> wanted to use it for my coco because I had heard it was a good
> 
> display for the 80 column mode. The first difficulty I ran into
> 
> interfacing the 1080 and the coco was the lack of an available
> 
> pinout for the 1080's RGB connector. Further research eventually
> 
> yielded the information that the 1084 pinout was the same as the
> 
> 1080. After finding the correct pinout (at pinouts.ru) and making
> 
> a couple false starts I eventually found the correct information I
> 
> needed to make this combination work. One of the mistakes I made
> 
> was getting the HSYNC (horizontal sync) and VSYNC (vertical sync)
> 
> signals going to the monitor correctly. At first I assumed (for
> 
> various reasons) that I needed to invert the HSYNC and VSYNC so I
> 
> made up a little circuit using a 74ls04 hex inverter chip. This
> 
> didn't work and was completely off the mark as I later found out
> 
> (these chips are maybe 50 cents each so it wasn't a big deal
> 
> moneywise). Then as I was glancing through an old Rainbow I came
> 
> across the information I needed in Marty Goodman's column. The
> 
> chip I actually needed was a 74ls02 NOR gate to combine the HSYNC
> 
> and VSYNC into one CSYNC (composite sync). So I made up another
> 
> little circuit using a 74ls02 and 14 pin socket, an LED, a switch
> 
> and an external 5 volt power supply. I had originally intended to
> 
> grab 5 volts from the coco internally but I just wanted to get this
> 
> thing working and it was easier to use the external power supply.
> 
> If you want to try this yourself be warned - this only works if you
> 
> have a 1080 (or 1084) with the 9-pin D-type RGB connector, not the
> 
> round 6-pin DIN type connector. If your monitor has the DIN
> 
> connector you lucked out - you won't have to add any circuitry at
> 
> all.
> 
> Parts list:
> 
> 14 pin 74ls02 NOR gate (dual input)
> 14 pin socket
> LED
> Switch (I used a double pole single throw slider I had laying
> 
> around)
> 5 volt power supply (I used 5volts 200 mA)
> 1k ohm resistor (I didn't need it and you won't either if you get
> 
> the right LED)
> A small project board to attach everything to
> 
> Note: For your power supply you need 5 volts and keep the milliamps
> 
> below 400. Also, you might have to test the lines for positive and
> 
> negative if you bought the power supply at a surplus store (like I
> 
> did). If you don't know which line is positive and which is
> 
> negative it won't work and you might let the magic smoke out. You
> 
> can use a mulitmeter to find out which is which.
> 
> The Cable
> 
> For the actual cable I cobbled together a 10 pin header with ribbon
> 
> cable attached (from an old motherboard serial port connector), a 9
> 
> pin D type connector with ribbon cable attached (again from another
> 
> old serial port), and a length of Ethernet cable. Special care
> 
> must be taken when connecting the D end. The wires are not
> 
> sequential with the pins! Pin 1 is wire 1, pin 2 is wire 3, pin 3
> 
> is wire 5, pin 4 is wire 7 and so on.
> 
> The Pinouts
> 
> Coco (looking at the bottom with the back of the coco facing away
> 
> from you)
> 
> 2 4 6 8 10
> 1 3 5 7 9
> 
> 1 ground
> 2 ground
> 3 Red
> 4 Green
> 5 Blue
> 6 No pin
> 7 Sound
> 8 HSYNC
> 9 VSYNC
> 10 Not used
> 
> Amiga 1080 RGB D-type (looking at the back of the monitor)
> 
> 1 2 3 4 5
> 6 7 8 9
> 
> 1 ground
> 2 ground
> 3 Red
> 4 Green
> 5 Blue
> 6 Not used
> 7 CSYNC
> 8 Not used
> 9 Not used
> 
> Note: Pins 6, 8 and 9 are used with other computers, just not the
> 
> coco.
> 
> Cable Assembly:
> 
> I started at the coco end, attaching pins 1, 2, 3, 4, 5, 8 and 9 to
> 
> the Ethernet cable. The Ethernet cable is conveniently
> 
> colour-coded so make a note of what wire goes to what colour (eg.
> 
> pin 1 to blue, pin 2 to blue/white etc.). At the Amiga end I
> 
> attached the corresponding wires to pins 1, 2, 3, 4 and 5 (making
> 
> sure I followed the wiring scheme I noted earlier wherein pin 1 is
> 
> wire 1 and pin 2 is wire 3 and so on). When you've finished this,
> 
> check the connections for continuity using a mulitmeter.
> 
> The Circuit Board:
> 
> switch
> ----- + ------./ .-----w-----|O|----------------------|
> | 5v | resistor LED ______ |
> ----- 1-| 7 |-14----
> neg 2-| 4 |-13
> | 3-| L |-12
> | 4-| S |-11
> | 5-| 0 |-10------------|
> | 6-| 2 |-9-------| |
> |----------------------------------- 7-| |-8--| | |
> ------- | | |
> | | |
>> From coco pin 8 ------------| | |
>> From coco pin 9 -----------------| |
> To Amiga pin 7 -----------------------|
> 
> Connect +5 to the switch and run it to the LED. Make sure you have
> 
> the LED oriented correctly or it won't work - usually the long wire
> 
> is positive. Also, unless you have an LED with a built in resistor
> 
> (mine does) you should put a resistor in front of the LED (a 1k ohm
> 
> resistor will do in a pinch). Connect the negative end of the LED
> 
> to pin 14 of the 74ls02 and attach pin 7 to the negative side of
> 
> the power supply. Attach wire 8 from the coco to pin 8 of the
> 
> 74ls02 and wire 9 from the coco to pin 9 (easy eh!). Now attach
> 
> the wire from pin 7 of the Amiga's RGB to pin 10 of the 74ls02.
> 
> When you turn the switch on the LED should light. If it doesn't
> 
> light up then check your connections (and didn't I warn you about
> 
> the resistor?).
> 
> My circuit board looks a bit messy right now so I'm going to redo
> 
> it and pack it into a little project box I picked up for $2.00. I
> think I'll even add a jack for the power supply.
> 
> 
> 
> 
> On Fri, Mar 28, 2014 at 10:14 PM, William Haywood <
> firstsecondary at verizon.net> wrote:
> 
>> Does any one know which 1084S-xx monitors will work with the coco3?
>> Without combining the Horz -Vert Sync?
>> 
>> 
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> 
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