My guess is that the video out could be composite but not sure why 3 pins, have seen some odd composite outputs that use a special cable to change a 4 pin into two RCA plugs (one for yellow Video, the other for Mono audio). Maybe the proper cable for that video out does same with a shared ground. Just guessing....

I came across this, but it's made for audio (vintage Grunding and Telefunken to be more exact). However for conduction purposes only, should work with video if pin scheme is the same:

Easiest way to see what goes where would be to open it up and take a look.

My guess is that you will just short things out if you try to use the cable above.

From what I could find, that 3-pin output may be a monochrome output but couldn't find any actual information on the pinout. If it is a monochrome pinout, it may be fairly easy to convert the unit to have color output.

Really just need to open it up and see what is available.

cyclone3d wrote on 2020-05-20, 01:25:

Easiest way to see what goes where would be to open it up and take a look. […]
Show full quote

Easiest way to see what goes where would be to open it up and take a look.

My guess is that you will just short things out if you try to use the cable above.

From what I could find, that 3-pin output may be a monochrome output but couldn't find any actual information on the pinout. If it is a monochrome pinout, it may be fairly easy to convert the unit to have color output.

Really just need to open it up and see what is available.

Good point ! I saw a similar three pin while googling and it went into a powered conversion box to convert video out but no good description, not for same unit but without knowing where those three pins come from could be a disaster if hooked up wrong.

I found this article about the computer: http://v8bits.blogspot.com/2009/09/saida-vide … monitor-no.html
There is a nice pic of the port: http://1.bp.blogspot.com/_hK1-3x9rtf8/SrQceGH … 00/DSCN0274.JPG

Hope it helps. Brazilian "mystery IOs" may become a problem.

Volo wrote on 2020-05-20, 07:55:

I found this article about the computer: http://v8bits.blogspot.com/2009/09/saida-vide … monitor-no.html
There is a nice pic of the port: http://1.bp.blogspot.com/_hK1-3x9rtf8/SrQceGH … 00/DSCN0274.JPG

Hope it helps. Brazilian "mystery IOs" may become a problem.

These pictures are from the tutorial that converts the TV out to Composite Video out. Seems to be easy for those who are skilled on soldering.

cyclone3d wrote on 2020-05-20, 01:25:

Easiest way to see what goes where would be to open it up and take a look. […]
Show full quote

Easiest way to see what goes where would be to open it up and take a look.

My guess is that you will just short things out if you try to use the cable above.

From what I could find, that 3-pin output may be a monochrome output but couldn't find any actual information on the pinout. If it is a monochrome pinout, it may be fairly easy to convert the unit to have color output.

Really just need to open it up and see what is available.

The CP-300 is monochrome only, like the original TRS-80 (not the CoCo version).

Perhaps one of the pins is for luminance (or Luma, aka "Y" in Y/C), another pin is for Audio then the rest should be ground.

You could try and poke around with an oscilioscope to find a potential video signal... But that's something that might be hard to grasp for some people.

Vynix wrote on 2020-05-20, 23:22:

Perhaps one of the pins is for luminance (or Luma, aka "Y" in Y/C), another pin is for Audio then the rest should be ground.

You could try and poke around with an oscilioscope to find a potential video signal... But that's something that might be hard to grasp for some people.

The computer is a clone of a TRS80 Model 3, which in turn was a "all in one" version of the TRS80 Model 1. No sound, no colour, limited mosaic graphics (2×3 blocks in each character cell).

As far as I know most the closest thing to sound on a Z80 based TRS80 was by generating rf noise from the computer which was detected by an AM radio tuned to a quiet/empty frequency.

My money is on GND, +5V, and video. That would allow an external RF modulator to be powered directly from the computer. The Model 1 (5 pin DIN) had such an arrangement (UM1233 modulator in a small box).
I note that this computer already has a modulator built in, so its possible that the video connector simply has three pins because the 2 pin DIN connector is only ever used for speakers (slot+pin).

Personally I'd use a multimeter to determine the pins by measuring the voltage, noting that on a digital multimeter a +5v source will be immediately obvious, and video signal will show as a weak voltage source. (Use a multimeter set to a 10V DC range, do not use a moving coil meter also known as (aka) "a meter with a needle").

Sound is played through an internal speaker (the volume knob on the back controls it) which can also play digitized voices:
https://www.youtube.com/watch?v=4M3xs3vOu7M
I'm guessing it's the same person who made the TV out to Composite out conversion tutorial as the image is incredibly clean in this TV and you can see he's using an A/V cable.

mdog69 wrote on 2020-05-21, 07:11:

My money is on GND, +5V, and video. That would allow an external RF modulator to be powered directly from the computer. The Mode […]
Show full quote

My money is on GND, +5V, and video. That would allow an external RF modulator to be powered directly from the computer. The Model 1 (5 pin DIN) had such an arrangement (UM1233 modulator in a small box).
I note that this computer already has a modulator built in, so its possible that the video connector simply has three pins because the 2 pin DIN connector is only ever used for speakers (slot+pin). That would allow an external RF modulator to be powered directly from the computer. The Model 1 (5 pin DIN) had such an arrangement (UM1233 modulator in a small box).
I note that this computer already has a modulator built in, so its possible that the video connector simply has three pins because the 2 pin DIN connector is only ever used for speakers (slot+pin).

Personally I'd use a multimeter to determine the pins by measuring the voltage, noting that on a digital multimeter a +5v source will be immediately obvious, and video signal will show as a weak voltage source. (Use a multimeter set to a 10V DC range, do not use a moving coil meter also known as (aka) "a meter with a needle").

Wow "the My money is on GND, +5V, and video" and "That would allow an external RF modulator to be powered directly from the computer. ". That explains what I saw in google search, think it was a Model 1 (but could be wrong) but that does make sense with what I saw when searching for info. Thanks
Sorry can not add anything extra to help.

As you may see on the pictures - there are 4 different wires. They may quite be
1. Shield Ground
2. Signal Ground
3. VCC, and
4. Composite.

But since this thing came with it's own monochrome monitor - it may quite be:
1. Ground,
2. H sync,
3. V sync, and
4. Signal.

You still need an oscilloscope to figure it out.

That appears to be identical to the common 5 wire color analog cable I have.

Only way to know is to put probes on each wire or open er up and see where the pins go

Ground and 5v is easy to ID,

Good luck