Composite out of RF out

[protek]

I know that STs with RF emulator have composite in the RGB port but as the 13 pin DIN connector is relatively rare, I thought I'd ask if this alternative would be possible.
The Sinclair Spectrums have only RF out by default but it can be modded to give composite by bypassing the RF modulator. Would the same be possible in the ST? I take it is composite that is fed to the RF modulator. That way tou could get composite out with a bog common RCA cable. Of course you need to get sound by some other means.

[Nikolas]

viewtopic.php?f=74&t=15728

i got s-video, thats 4 pin video (output conects to tv box, then out to DVI signal, for monitor)

rca, for audio output (that conects drect to monitors speakers)
http://imageshack.us/photo/my-images/88/dscn1273f.jpg/

[NikiforosST]

Atari's with build in rf modulator have composite video out at pin 2 of monitor out socket. Atari's with NO rf modulator there have only composite sync! you can't take composite video of RF signal, you must take it from inside, like Nikolas told you take s-video and then you can make it composite with an cheap adapter!

[Silly_Pony]

Atari's with build in rf modulator have composite video out at pin 2 of monitor out socket. Atari's with NO rf modulator there have only composite sync! you can't take composite video of RF signal, you must take it from inside, like Nikolas told you take s-video and then you can make it composite with an cheap adapter!

...Yes, that's what he said.

He wants to take the composite signal from inside the machine, because monitor connectors are hard to get.

He mentioned the ZX spectrum mod. To do that, you remove all the parts from the RF modulator, so RF socket becomes composite.

If I still had an STFM around I'd do the mod. Can't be very hard at all. Only difference is the ST's RF modulator will have an extra input for audio.

[NikiforosST]

Atari's STFM composite video signal is on the pin2 on monitor plug, a modification is neccesary to take ONLY S-video signal from MC1377 pins like here : viewtopic.php?f=74&t=15728 Only Atari's with NO RF modulator can't have composite video on pin2 monitor output but only composite sync there.
http://www.ebay.ie/itm/Atari-ST-Quality ... 3cbaae9ba5
this cable is composite video and sound for Atari's STFM (with rf modulator).
Spectrum or other computers hardware modifications are irrelevant with Atari's STFM!
So there isn't any reason to take composite video from RF signal! like topic says!
Pin 13 plugs you can find on ebay, http://www.ebay.ie/itm/13-PIN-DIN-MALE- ... 0449053016
kenwood and roland music machins have the same plug!! you can solder an RCA plug in the back of your STFM! and you don't need the cable, but on ebay have many of them!

[Silly_Pony]

£5.59 for Atari 13-pin plug. Plus cost of cable, etc.

The ZX spectrum mod is very relevant. RF modulator works in exact same way.

I don't know why you take such a hostile tone. You don't even understand people's posts.

[NikiforosST]

Sorry my English isnt so well and some times maybe look like hostile tone. I dont meant anything! I have understand very well the other posts! but the title on the topic is wrong, we cant take cvs signal from rf out. I said some solutions, now you can do the better solution. You can solder a rca cable under the STFM motherboard (from monitor pins out) and then on the back side have cvs out! is the cheaper solution! To do the resoldering mod you must know what parts must stay and what parts dont need. I think that it is very difficult to do this and then work. I prefer to soldering a rca cable on the pin out (pin 2) under the STFM motherboard. I have solder some outputs on mine, like SVGA 15pins monochrome out and 2 RCA audio out. My STFM has broken MC1377 and i havent any RF and composite video signals at all i must change the motorola MC1377 Chip. I have take away the RF modulator from mine...a rf choke had explode
http://womblesretrorepairshack.blogspot ... o-mod.html
this is the mod, cant be done in Atari st fm! rf modulator there have other parts, some photos...

[NikiforosST]

http://www.youtube.com/watch?v=TJlyUepv7KQ

Youtube video with Spectrum composite mod in RF modulator.

Another mod in Atari 2600, makes RF out to CVS! but i can't find nothing for Atari STFM!

In the second photo with the schematic, pin 9 on chip MC1377 gives composite video signal, afther transistor Q1 we can take the composite video signal, this is the signal goes into RF modulator.
As we can see in the picture below, many many parts are SMD type, so it's very very very difficult to do something with them.

[Silly_Pony]

Taking composite from the modulator is not the goal, just to replace RF with composite. The point of the mod is to reuse the scrap Modulator's RF connector, and keep it looking standard.

Inside the atari, you can run the wire from anywhere you like. Nobody said otherwise.

[NikiforosST]

Ok, but nobody has done this mod to take composite video out from RF connector on STFM,i have looked over the internet again and again, this can happen only in some other machines like atari 2600 (with an extra circuit board) and spectrum computer. That's why i said before some other solutions....if you know how to do this mod write a tutorial please. Others machines RF modulator are completely different from Atari's STFM. Some STFM have a big RF modulator like here : http://www.apqb57.dsl.pipex.com/STMothe ... FM_Dio.jpg my STFM has a small RF modulator, both are from MITSUMI company. This is mine : http://www.surplustraders.net/specialis ... TORS-TH228 and http://img01.taobaocdn.com/bao/uploaded ... 10x310.jpg
To do the mod we must know the inside schematic, unfortunatelly i can't find it

[1st1]

This one will help you, but it is a bit more complex:

-> http://www.epanorama.net/circuits/vga2t ... lntsc.html

As you can see, you get Composite and S-Video from this circuit.

Don't look to much on the word "VGA" in there, as later they write that the refresh rate of the VGA card must be able to be compatible to PAL or NTSC standards, that means, video signal must be same as Amiga or ST.

[NikiforosST]

Nice schematic and maybe easy! but i have already begin a external board with MC1377 chip like this inside STFM's! from RGB to Composite video. The AD7XX chip is much better than MC1377 and wants 5Volts power supply, MC1377 take 12volts. The story here like topik says is to take CVS from RF output, so no external boards and modifications on STFM case!
http://www.ebay.ie/itm/Atari-ST-Quality ... 3cbaae9ba5
This cable is very cheap and have RCA outputs, with STFM we have composite video, like i said mine STFM has issues with MC1337 inside chip and i cant have composite video signal on pin 2! soon i will replace it, i have order a new one from ebay.
This is what i am building now, with some modifications we can take Svideo signal instead composite.

[simbo2]

you need to use 13077 ic for modern lcd to get the right svideo flags to trigger the right scaling prestates
they are embedded to the carriers
here is a pic
you can have this 'kit' and play with it
i made it some years ago
but ppera decided to post a hack to the main pcb and modulator of the st and ste
this is a long term solution where pperas just is not
i withdrew the project
and instead i sent 90 built boards to a certain museum as a job lot to convert all there machines to svideo for there massive video wall
anyway here is a pic
i can repost the schematics and have!!!
or even send you a complete kit or the pcb layout or a few pcbs...
you can drive from a cable from the atari or internal
via its own proper svideo sockets!!! 8 pin 4 pin or two pin
the 13077p is far better i have 10 left and its a hard ic to find!!!!
this is exactly the problem i created the design for
but ppera made it hard to make people see the benefit from more flagging of svideo
ok found the schematics and designs etc support docs {read them!!!}

dont forget dont try to extract this file in other than a root dir or it may not work
zip 64 and long file names issues with some o/s so the archive looks crc wrong
move it to like d: it de-packs

[NikiforosST]

Thank you for the infos!!! ) but already i have begin the other circuit with MC1377 and in a few days maybe finish it! i want to take composite video out to connect my STFM in a tv card on my linux box. I have ordered a new MC1377 from ebay to change the chip inside my ST because i have burn it some how and i haven't composite sync or video at all on pin2, or pin 9 on MC1377 chip! i wish to work again! then with some modifications on H/W like ppera site we can take svideo signal instead composite video. Scart cables either work on my ST! and finally i take 2 registors 150ohms each one from H and vertical sync (from st output) to pin 20 on scart cable and then i have Csync from H+Vsync!!! a small cable between pin 16 and pin 20 on scart connector and now scarts working on my STFM!