S-Video mod for STE, ST ...

[ppera]

This is easy to do, almost free (only need to buy cable with S-Video connector) modification for STE, ST or even Falcon. After it, you will have not composite out more (but will have B/W on regular out), just to mention, but who needs it, when have much better one.
Will have much sharper, cleaner picture via TV card on PC, or TV with S-Video input.

Modification of STE's PAL encoder for getting S-Video:
STE's PAL encoder, modded :

svidste.jpg

Hardest part is to removing DL1 (reactangle shape plastic) and L403 (square shape, metal with hole at top). You need soldering iron, at least of 60W and vacuum pump. Disassemble machine, so can desolder from bottom side of mainboard. It is not so simple, and requires some practice. Need to hold soldering iron for longer at pins, that it can melt at both sides of pcb. Especially is hard to desolder pins where GND is, as there are wider copper leads, which pull a lot of warmness.
After it is easy. Add wire between left pin of R467 and right pin of resistor below. On pic, it is grey wire painted to blue at middle. Actually, it connects pin 8 of MC1377 with resistor of 1.2 K. See schematic lower.
Last thing is to make output connections. I used 4 wire cable where 2 middle line is soldered to GND and 1 line is for Luma - solder to pin 9 of MC1377. In some cases it needs to pass through electrolythic capacitor of some 47-100 microFarads, what depends on input of atached device (TV card, TV, VCR). Other output is chroma of course, and it goes to pin 13 of MC1377. Chroma must pass through ceramic capacitor of about 47-100 nF (not visible on pic). I just use here one floating connector, so can use same S-Video cable with many Ataris.

Other Atari computers:
1040 STFM, Falcon (or even other revisions of STE, Mega STE) have very similar PAL encoder, but component placement is different. Of course, mod is same - removing delay line and coil. Connecting pin 8 with 1.2K res. You need to find that resistor on board, what is not hard, and connect to opposite pin than which is connected to pin 6 of MC1377.

PAL encoder in 1040STFM (unmodded) :

1040stfmpe.jpg

Mega STE's PAL encoder, modded :

mstesvid.jpg

Schematic of PAL encoder:

stencoder.png

Little more can find here, with some screenshots, videos: http://www.ppera.07x.net/atari/stvid.php

[techie_alison]

What about the NTSC crowd. This seems to affect them much more than it does us.



Good work though, I've been waiting to see this actually documented by somebody for ages.

[ppera]

I think that same mod. is good for NTSC too. Basical principle is same. But I can not test it, as have no NTSC machine.
It would be good, if someone brave on other side of Atlantic spend little time to do this mod. in his Atari and inform us...

I checked datasheet of MC1377. Only difference between PAL and NTSC is chroma carrier freq (what depends from used crystal in oscillator) and that by NTSC pin 20 is connected to GND. So, this mod. is good for NTSC too 99.9999999999999999 %

[McCarthy]

Hello there,
I'm new here and I stumbled upon this thread while I was looking for an RGB to Composite circuit for the Amiga2000. Since I'm possessing an Atari STFM it would be great to get this to work too. I was wondering if it's possible to get a composite color out instead of the S-Video?
Cheers, McCarthy

[simbo]

You can get composite out the video socket already if you have an stfm but not the plain ST or STF. {no modulator ie has no 'tv' phono on the rear for tv rf connection}

mega st and mega ste i think even a TT and falcon does this trick. as long as they have the modulator and or support circuit
mc1377p chip {tv out yes other no}

http://www.retrocomputing.net/parts/ata ... tor_st.htm

pin 2 is general purpose output and will plug direct into the yellow svideo socket on tv's etc.
pin 13 is ground or the shield of such a two pin cable
An audio output to tv is availble here also,
and wiring two phono plug togther to the audio output and again ground shield,
would give a mono output to both channels for nice audio..

[McCarthy]

Hello there
now I have time to play around with my Atari STFM. I know the answer comes a little bit late
I soldered a nice Atari -> Composite cable with the help above, but it doesn't work for me. I measured the cable with a multimeter and it seems to be ok, so no problems on that side. I thought maybe the monitor-out of my Atari is messed up, so I tested it with another Atari. But all I can get is a black screen on both machines. The only thing I get is a beep from the speakers whem I press a key on the keyboard.
I made a little drawing of my soldering the view is onto the monitor-out socket of the Atari.

[simbo]

pin 2{corrected} and 1 and 13 as you have it is fine

you need to connect pin 13 and 3 to the yellow socket on a tv composite video
i know this works becouse i use my tv card on the pc the same way
a black screen doesnt sound right for sure
if its an stfm you have
as the stfm/mega/ste does supply the GP output via pin3 of its video socket

if you get sound its the right way around

have you tried another video into the svideo socket on your tv etc... to confirm this works

[McCarthy]

Thanks for the reply, but I think it's PIN2 I have to use, because now it works. I desoldered it from PIN3 and soldered it to PIN2 et voila it works. Before I did this I've read a few articles about ATARI pinouts, many of them said that Composite lays on PIN2. I'm a little bit confused why it works for me, because you said that your way works for you. http://pinouts.ru/Video/AtariStMonitor_pinout.shtml this for example says that on PIN2 lays Composite-Video, so does this http://pzat.meep.org/computing/st_connectors.html#monitor. But yours says that on PIN2 lays Composite-Sync http://www.retrocomputing.net/parts/atari/1040STF/docs/connettore_monitor_st.htm. That's odd, mhhhh.
Cheers, McCarthy

[simbo]

nice one atleast you saw past even my bad postings of numbers

i just took it for some reason GP output was composite out

anyway alls well that ends well
i check past posts and ive posted correct pins in other posts

never mind

[McCarthy]

I have to thank you. No problem with the PIN issue, everyone does mistakes
Cheers, McCarthy

[DarkLord]

Has anyone actually done this mod and tried it with modern TV's, LCDs, or monitors?

Since no one has actually come through with a final end-user product for color ST
to VGA/LCD products, this is starting to look like the only option for me to attempt
to get my STacy's video output to a replacement screen.

Thanks!

[1024MAK]

Has anyone actually done this mod and tried it with modern TV's, LCDs, or monitors?
Since no one has actually come through with a final end-user product for color ST
to VGA/LCD products, this is starting to look like the only option for me to attempt
to get my STacy's video output to a replacement screen.
Thanks!

The mod listed above in this thread and using the composite video out (pin 2) will only work if the machine is fitted with a MC1377 chip. This chip encodes the "baseband" (or raw) red, green and blue video signals (RGB) along with the vertical and horizontal sync signals to produce the composite video signal (hence the name - composite - made up of distinct parts or elements). It is this signal that the modulator needs in order to produce a UHF TV signal that can be connected to the aerial input on the TV.
Normally you only get a MC1377 chip if the machine comes with a modulator .
No modulator, no MC1377 chip, therefore no composite video signal . On these machines pin 2 is just a composite sync signal (a mix of the vertical and horizontal sync signals only).

If you have a machine without a modulator, the simplest solution is to use a display that can take analog RGB signals.

It is possible to build a colour encoder that does the same job as the MC1377 chip, but you do need to be able to produce your own circuit board (PCB) and design and build the circuit (which is beyond most people).
The next best thing is to find a piece of equipment that has such a circuit, carefully saw the circuit board so that you end up with only the colour encoder circuit, then wire it up. However finding a donor device / machine is easier said than done (unless you are happy to hack another Atari up.... ). You also need to work out the connections - again easier said than done (but the data sheet for the chip helps ).

MC1377 data sheet: http://www.datasheetarchive.com/pdf-dat ... 81104.html

Other colour encoders (there may be more than I list here, this is just a selection)
AD725 data sheet: http://www.analog.com/static/imported-f ... /AD725.pdf
AD722 data sheet: http://www.eecg.toronto.edu/~tm3/ad722.pdf (note that this chip is listed as obsolete)
Video-Standard Selection Circuit for the AD722 Using Low Cost Crystals: http://www.analog.com/static/imported-f ... AN-412.pdf
Example circuit, VGA to PAL and NTSC converter: http://www.epanorama.net/circuits/vga2t ... lntsc.html <<<well worth having a look at this
see also http://www.analog.com/en/audiovideo-pro ... index.html

MC13077 data sheet: http://www.classiccmp.org/rtellason/chi ... c13077.pdf or http://www.alldatasheet.com/datasheet-p ... 13077.html
TDA8501 data sheet: http://www.nxp.com/acrobat_download2/da ... _CNV_2.pdf
NTE879 data sheet: http://www.nteinc.com/specs/800to899/pdf/nte879.pdf
TEA2000 data sheet: http://www.alldatasheet.com/datasheet-p ... A2000.html
Example circuit: http://www.next.gr/inside-circuits/PAL- ... l5859.html

More info on video circuits and chips: http://www.epanorama.net/links/videochips.html

Note also that if you do not wish to modify your Atari like shown in the mod listed above in this thread, the signals needed for an external colour encoder are R, G and B video signals plus, H sync and V sync all of which are already available on the Atari monitor connector (see Example circuit, VGA to PAL and NTSC converter in this post just above).

Hopefully I have explained this well

[DarkLord]

Ah, kk - I missed that part about it having to have the modulator onboard in the first
place.

Bummer, another idea gone down the cesspool drain of wasted thoughts.

[simbo]

just get a cheep jamma board from ebay {£13inc post}
and an lm1881 or a maxim sync seperator chip { i use free samples}
be done with it
ive been using one for the ste for 2 years now but it cost me £26

plug to svga use st or ste and it scales etc
http://www.jammaboards.com/store/video- ... 1a864e1453

not ebay but youll find the same thing there
gbs8220 works well once properly set up

[DarkLord]

just get a cheep jamma board from ebay {£13inc post}
and an lm1881 or a maxim sync seperator chip { i use free samples}
be done with it
ive been using one for the ste for 2 years now but it cost me £26

plug to svga use st or ste and it scales etc
http://www.jammaboards.com/store/video- ... 1a864e1453

not ebay but youll find the same thing there
gbs8220 works well once properly set up

Wait, isn't that the chinese board I bought a couple of months ago and never
could get it to work? I thought I'd brought it up in another thread?

viewtopic.php?f=15&t=17153

Thanks.

[1024MAK]

Another member (Anemos) in another thread brought my attention to this RGB to PAL/NTSC Adapter
See http://www.amigamaniac.com/RGB_to_PAL_NTSC_adapter.html
This adaptor circuit generates both composite video and s-video outputs from a RGB (and V & H sync) inputs.
See also http://www.ultimateamiga.co.uk/index.ph ... 383.0.html

[DrCoolZic]

just get a cheep jamma board from ebay {£13inc post}
and an lm1881 or a maxim sync seperator chip { i use free samples}
be done with it
ive been using one for the ste for 2 years now but it cost me £26

plug to svga use st or ste and it scales etc
http://www.jammaboards.com/store/video- ... 1a864e1453

not ebay but youll find the same thing there
gbs8220 works well once properly set up

Wait, isn't that the chinese board I bought a couple of months ago and never
could get it to work? I thought I'd brought it up in another thread?

viewtopic.php?f=15&t=17153

Thanks.

Yes this is the same board and apparently Anemos was able to use it. I am still in middle of tests myself. From What I understand the only problem left is the fact that the sync signal is too high for the board and I need to add a resistor on the sync input. Just need to find the right resistor and TIME to finish the test.

The advantage of this solution is that you can connect directly an LCD to the board while the "Amiga adapter" solution also requires to have an s-video to VGA converter

PS I have posted an inquiry on the Kjmann thread to find out what is the status of the atari to s-video project! Few weeks ago the prototypes where ready but still nothing available!!!
http://www.atariage.com/forums/topic/14 ... t-systems/
http://atari-sales.com/forums/showthread.php?tid=25
http://atari-sales.com/forums/showthrea ... 142#pid142

[DarkLord]

Just out of curiosity, what lines commonly have to have resisters added?

(also, ranges for the resisters would be nice too!).

Thanks!

[DrCoolZic]

Just out of curiosity, what lines commonly have to have resisters added?

(also, ranges for the resisters would be nice too!).

Thanks!

I do not think it is necessary to add resistors on the RGB because there are 3 potentiometer that allow to calibrate the colors.
However the sync signals probably needs a 510 Ohm resistor but I have not yet tried.

[simbo]

i made an any st to component svideo using a mc13077p some years ago
there was VERY little interest here

lucky for me a retro museum in france took all my stock of boards

i think svideo is a waist of time...
far better to use some converter/ scaller for vga
most TV these days uses vga also

dont know if i would 'hack' the board's encoder section to bits to add it

you can pass a copy of this archive to the guys making there svideo adapter
as they may find it usefull

[DrCoolZic]

Thanks for the reply, but I think it's PIN2 I have to use, because now it works. I desoldered it from PIN3 and soldered it to PIN2 et voila it works. Before I did this I've read a few articles about ATARI pinouts, many of them said that Composite lays on PIN2. I'm a little bit confused why it works for me, because you said that your way works for you. http://pinouts.ru/Video/AtariStMonitor_pinout.shtml this for example says that on PIN2 lays Composite-Video, so does this http://pzat.meep.org/computing/st_connectors.html#monitor. But yours says that on PIN2 lays Composite-Sync http://www.retrocomputing.net/parts/atari/1040STF/docs/connettore_monitor_st.htm. That's odd, mhhhh.
Cheers, McCarthy

Everybody is a little bit right
What you need to know is that
- if an Atari ST has an RF modulator installed like your STFM then pin 2 carry a composite VIDEO
- But an Atari without RF modulator installed will have composite SYNC on pin 2 and this type of system does not allow to connect to TV directly

For more info look at my page http://info-coach.fr/atari/hardware/int ... _connector

[simbo]

there is also the problem that older output composite
doesnt contain the correct flagging to provide proper scaller picture enhancement
done by lcd for widescreen

only the later ic mc13077 provides this flagging and output
whilst also providing seperate X and Y svideo and ntsc compatable

something the hard hack fails to complete
especialy as ppera for some reason used a ribbon cable and not individual screened coax or overlap cable
as his usual hack are its about on par

this unit is fully external in a box as the french museum wanted and i made them 60 for there video wall
or internaly monted as they used 0... not even for the st range i wonder why??

mc13077 is hard to find ish
i have 5 spare ic's here and maybe 3 or 4 boards
i use my own ones only for driving the pc video capture card

as for display i use a sm124 or a tv {with a few mods} and drive the tv at the tube base amplifier
sony FST is a great choice all round
and everyone should own an analogue tv

[simbo]

as for jamma vga boards i still have problems with dynamic sync

i see a V3 version or later
on the board is a hardware access port for flash
i have the details and i can make a cable in 1 min

but for flash parts it seems this chinese company holds out
just making a single product work as i seem too see v1 v2 and v3 use the same chipset in full for the board type
and they havent made a new move....

and hogs its flash parts

totaly terrible

however mine seems to work using a lm1881 with st or ste
but needs to reset before the st on boot
using a gate linked to reset is needed {add an output from the atari for reset pulse}
so i think looking i may have a v2 or later

think v1 works only with st machines

v3 not sure

please people help me for one decode the chinese script???
whats the script m8's??? where is it in the bin ... and no soy...
請給我們gbs8220的固件閃光关于版本3固件和纜繩的細節用戶的能更新您的產品 谢谢

[wongck]

whats the script m8's??? where is it in the bin ... and no soy...
請給我們gbs8220的固件閃光关于版本3固件和纜繩的細節用戶的能更新您的產品 谢谢

don't look at me.... I can't read them chinese characters... sorry.
I also use Google, just like you would.

[simbo]

Example circuit, VGA to PAL and NTSC converter: http://www.epanorama.net/circuits/vga2t ... lntsc.html [size=150]

why look at this ???? all the AD722 723 are for interlaced video and not atari non interlaced

been there done that the best ic for the job is the mc13077p .. there is really no other
can do non interlaced well