Against my better judgment, I dragged my old Atari 800 out of storage. Way too many other projects to work on and at least one I need to finish but I got the yen.

Currently I have the RF connection to my TV jury rigged but it does not seem to work. Have a proper connector on order. But I was wondering if there is a way to confirm RF out is working with my scope. The only thing I am seeing is what looks like noise down in the mv range. Been centuries since I worked in TV. Should I be able to see TV RF on the scope?

I do see composite video out. View attachment 174453


Plus the computer makes power up noises and keyboard clacks from the internal speaker so I am pretty sure the CPU is working.

I would like a backup plan of using video. What I am not sure of is how to hook up the video output to a modern TV. It was easy back in the back in the day when all I had was a B/W monitor that I hooked up. Along with TV theroy being fresher in my mind.

So how would I hook this thing up? Here is the Atari connector which is a 5 pin DIN.

Something like this:

3        1
 5     4
    2

1. Composite Luminance
2. Ground
3. Audio Output
4. Composite Video
5. Composite Chroma (not on 800XL,1200XL; grounded on 600XL)


I have video, Y, Pb, Yr connectors on the back of my TV. Is it possible to hook this thig up?

 

Looks like normal s-video.
https://en.wikipedia.org/wiki/S-Video
http://www.epanorama.net/circuits/svideo2cvideo.html

 

Looks like normal s-video.
https://en.wikipedia.org/wiki/S-Video
http://www.epanorama.net/circuits/svideo2cvideo.html

OK I am on Ambien right now and fading fast. Mybe it will sink in tomorrow but can you tell me what hooks to what in case it does not sink in?

 

 

Looks like all I need is composite video?

Does this look like it is composite video?


What about RF out?what should I see there?

 

View attachment 174498


Looks like all I need is composite video?

Does this look like it is composite video?


What about RF out?what should I see there?

The video carrier is at 61.25 MHz for channel 3, the probable choice for the RF modulator.

 

The video carrier is at 61.25 MHz for channel 3, the probable choice for the RF modulator.

View attachment 174499

I have it set to Channel 3. Not exactly sure what the chart means. What should I be seeing on my scope for RF out?

And does the photo above look like composite video?

 

The carrier is at 61.25 MHz, so you should see something at that frequency.

Yes, that waveform looks like composite video, like this one:

 

What kind of amplitude should I expect in the RF out?

 

Hello,

Wich atari version is it?
The 800 or 800XL.
The FAQ might answer some of your questions:
http://faqs.cs.uu.nl/na-dir/atari-8-bit/faq.html

Bertus

 

What kind of amplitude should I expect in the RF out?

About 90 dBμV relative to 1 μV into 50Ω

 

Hello,

Wich atari version is it?
The 800 or 800XL.
The FAQ might answer some of your questions:
http://faqs.cs.uu.nl/na-dir/atari-8-bit/faq.html

Bertus

The original 800.

 

About 90 dBμV relative to 1 μV into 50Ω

Ok what does that mean in respect to what I am seeing on my scope.

 

Ok what does that mean in respect to what I am seeing on my scope.

It should be about 31.6 mV into 50Ω. Do you have a terminator?

 

Hello,

You might be interested in the technical manual:
http://www.atarimania.com/documents/Atari_400_800_Field_Service_Manual_June_82.pdf

More can be found here:
http://www.atarimania.com/documents-atari-400-800-xl-xe-technical-documents_3_8.html
http://atariage.com/forums/topic/275630-atari-800-s-video-problem/

Bertus

 

Are you sure that the TV can work with analogue video ? Some modern TVs may only work with digital video. Do you know the carrier frequency ;from the RF modulator in the Atari and have you tuned the TV to that frequency ?. (I have not yet seen a modern TV that can't be set to analogue video mode as well as digital video mode.) If you are seeing the display in post #5 on your scope it is not modulated onto an RF carrier. If it is as in post #5 then you will need to feed it into a composite video input (NOT the RF antenna input.) This will be either on a phono (RCA) socket or the video in pin (20) of a scart socket. The video ground will be on pin 17 of the scart socket.

Les.

 

Hello,

The RF video seems to be able to switch between channel 2 and 3:



The image is taken from this book:
http://www.atarimania.com/documents/Sams_Computer_facts_Atari_800.pdf

Bertus

 

It should be about 31.6 mV into 50Ω. Do you have a terminator?

Guess not. Can I make one?

 

Hello,

The RF video seems to be able to switch between channel 2 and 3:

View attachment 174513

The image is taken from this book:
http://www.atarimania.com/documents/Sams_Computer_facts_Atari_800.pdf

Bertus

Yes it can.

Still waiting on my parts. On order is an RF adapter for RF input and a 5 pin DIN for video / audio.

https://dfarq.homeip.net/connect-atari-to-modern-tv-sets/

 

Are you sure that the TV can work with analogue video ? Some modern TVs may only work with digital video. Do you know the carrier frequency ;from the RF modulator in the Atari and have you tuned the TV to that frequency ?. (I have not yet seen a modern TV that can't be set to analogue video mode as well as digital video mode.) If you are seeing the display in post #5 on your scope it is not modulated onto an RF carrier. If it is as in post #5 then you will need to feed it into a composite video input (NOT the RF antenna input.) This will be either on a phono (RCA) socket or the video in pin (20) of a scart socket. The video ground will be on pin 17 of the scart socket.

Les.

Post #5 is composite video. I have both available.