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simon.plata

Simple DIY composite video mod

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Quick update on the simple composite mod I made to my 4 switch woody. As I said above, picture looks great on a CRT, and on most older (non-smart) LCD panels. HOWEVER, there are big image problems when sent to my 1st generation 4k LCD HDTV. While the color seem solid, there are major ghosting/double images occurring, no matter what settings I change on the TV itself. I blame the ever-worsening analog to digital chips in these newer TVs, which apparently can't quite cope with the hack's timings/signal strength.

 

 

 

Hi stlouisrod, have you tried to reduce the gain of the amplifier?

 

Gosthing could be produced by several factors, including unmatched impedance and overdriven signal. The RCA cable could increase the impedance and generate gosthing.

 

I tested it on different LED TV and I have got nice video image.

 

Best regards,

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Hi and thanks to everybody who tryed this mod.

 

May be I forgot to suggest to adjust the trimmer until you obtain the better picture in your set-up.

 

The calculated value is for 0dB gain and 1Vpp output which is the standar composite video signal span. However due to the tolerance of the components in the VCS board and the in the mod, it could be lower or higher than that. The trimmer was included to correct that deviation.

 

Best regards and enjoy!

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Thanks for the update, Simon. I wasn't clear.. the mod I tried is the pre-made one on Ebay: Atari 2600/7800 A/V Composite RCA Audio Video Mod Kit " IMPROVED SOUND KIT " 1G, not yours. I think yours offers more flexibility, and I plan on trying one of yours in the near future to see if it works better on my 4k.

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Hi all, guys!

I saw the great work with the two transistor video amplifier, and I am trying to do it, but I find two problems: First I am not sure about what parts to remove from my console. Mine is a USA NTSC 2600 revision 14, with two joystick ports. A code under the revision reads C015519. I can send a picture of my board if needed.

Second problem is I am almost unable to understand an electric scheme, so I need to see the solder path just to be able to copy it. Is possible to see the solder side so I can try to replicate?

Thanks a lot!

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Posted (edited)

I just put this together last night on an Atari Jr and it worked first time and it works great! Thanks @simon.plata!

 

Got to see my old Mega Man prototype game running again for the first time in a long time on my 1702 composite display.

 

I used 2% resistors except for one 5% which I graded and selected with a multi-meter as you suggested. I trimmed manually and didn't put in a variable resistor into the circuit. I did not grade the transistors so I guess I was lucky or not a perfectionist.

 

I don't have a scope so I didn't check the peak to peak voltage on the output. I have brightness / contrast on the front of the 1702 which I did tweak slightly.

 

I hooked the video / audio output to cables poking out the back but I intend to convert the RCA RF output connector to video output and add an audio out as well.

 

I'll add pictures later.

 

The video looks awesome! Now this will help me on some 2600 development which I have been returning to finish up a couple of old projects.

Edited by djmips

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Atari removed a 680 ohm resistor when they released the 4 switch version.

 

They later sent out a service bulletin to put it back in!

 

Fixed a lot of bad color problems!

 

It goes between pin 6 and 9 of the TIA chip!

post-7077-0-49361000-1556428563_thumb.png

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Posted (edited)

I wired the video out to the existing RF output - It's connected in the upper right in the RF area. Yellow wires are video.
The audio is wired underneath and I added a second RCA jack so I can use RCA cables to my monitor.
Wires are too long, I will shorten them later.

post-4397-0-38771000-1556436020.jpg

 

 

I'm not the best at the case mods. Too impatient!

 

post-4397-0-04752700-1556436047.jpg

 

I know you can't see the wires and removed components because they are under the shield in myphoto.

I used the following instructions.
https://www.thefuturewas8bit.com/index.php/2600jr_comp_mod

 

For 4 switch he also has.
https://www.thefuturewas8bit.com/index.php/2600_comp_mod

Edited by djmips

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Hi all, guys!

 

I saw the great work with the two transistor video amplifier, and I am trying to do it, but I find two problems: First I am not sure about what parts to remove from my console. Mine is a USA NTSC 2600 revision 14, with two joystick ports. A code under the revision reads C015519. I can send a picture of my board if needed.

 

Second problem is I am almost unable to understand an electric scheme, so I need to see the solder path just to be able to copy it. Is possible to see the solder side so I can try to replicate?

 

Thanks a lot!

 

For help in understanding an electric schematic check this out -> https://learn.sparkfun.com/tutorials/how-to-read-a-schematic

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For help in understanding an electric schematic check this out -> https://learn.sparkfun.com/tutorials/how-to-read-a-schematic

 

Thanks a lot for the link. To be true I am able to recognise the elements of the video amplifier, but main problem is I am not sure which one to solder to which one, this is why I want to see the solder side, justo to replicate it. By the way, in this scheme I am not sure how to solder R7 to C1. The resistor must be between the legs of the capacitor? :? I have no doubt about how to connect the transistors to the resistors R3, R4, R5 and R6.

 

post-62422-0-00139200-1511299299_thumb.p

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The C7 would be attached to either side of the resistor but you don't have to put on C7, the designer actually left it out of the final version.

 

 

Thanks a lot for the link. To be true I am able to recognise the elements of the video amplifier, but main problem is I am not sure which one to solder to which one, this is why I want to see the solder side, justo to replicate it. By the way, in this scheme I am not sure how to solder R7 to C1. The resistor must be between the legs of the capacitor? :? I have no doubt about how to connect the transistors to the resistors R3, R4, R5 and R6.

 

post-62422-0-00139200-1511299299_thumb.p

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Er... do you mean the capacitor C1 does not need to be installed?

 

Now I have to upload a picture of my motherboard, so the elements to be removed can be specifically indicated.

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Hello, very interresting topic ... I've installed TFW8Bit mod and the image is really too dark on a CRT and quite black on an LCD.

 

I will give à try to your mod, but as I'm a bit new to this game, could you make a list of the components to buy. It's easy for the resistors but I'm not sure of R8 (gain ?).

 

Thank you !

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Here is my motherboard. Can someone point what elements must I remove? Console is a 2600 NTSC from USA, with two controller ports, and I already removed the RF modulator.

 

58443871_10157115152679920_5065523637658

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Hello, very interresting topic ... I've installed TFW8Bit mod and the image is really too dark on a CRT and quite black on an LCD.

 

I will give à try to your mod, but as I'm a bit new to this game, could you make a list of the components to buy. It's easy for the resistors but I'm not sure of R8 (gain ?).

 

Thank you !

 

Read the entire thread. The 1477 is a 5K trimmer potentiometer set to 1477 ohms for simulation. You just need to either put in a trimmer pot there.

 

I didn't have a trimmer pot around so I just removed the 1K and added a 3.3K - my hack - I eventually intend to measure it's output on a scope to trim it correctly.

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Ok I understand :)

 

And is it possible to have the corresponding Gerbers ... or KiCad or whatever, just to try by ourselves and eventualy pass some orders on EasyEDA :)

Cause I tried with a prototype board, but all I got is a black screen :(

I missed something. And moreover, for me it's good to practice !

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Links are both broken. :(

 

Edit: Weirdly, they both work in the above quotation, although not sure if they point where intended. :)

 

cut/paste mistake.

 

Jr. mod that I used:

https://www.thefuturewas8bit.com/index.php/2600jr_comp_mod

 

4 switcher version

https://www.thefuturewas8bit.com/index.php/2600_comp_mod

 

If you need another model it might be on that site.

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I am going to follow this picture from the link you stated:

 

4-Switch-Vader-NTSC.jpg

 

This is from a NTSC Vader, not exactly my model, but I will remove the coil L201, transistor Q201 and resistor R209.

 

Someone can show a picture of the solder side of the simon.plata AV mod? I need to follow the traces...

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If you can ignore audio for the purposes of explanation, for this Mod, the three wires to connect from the 2600 are. VIDEO; +5 VOLTS; GROUND. The output of the Mod is just Video and Ground to a female RCA jack or male RCA cable.

 

The three connections are all visible from the component side of your 2600 motherboard. All three are detailed at the site I linked.

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Yes, I understand from where take the signals from the board. My question is to see the solder side of the AV mod, because I am not totally sure about what solder with what. As I stated in a previous message, I do not fully understand the scheme...

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Yes, I understand from where take the signals from the board. My question is to see the solder side of the AV mod, because I am not totally sure about what solder with what. As I stated in a previous message, I do not fully understand the scheme...

 

Reading schemes can be tricky no doubt. But the easiest thing to remember is that anywhere you see a small 'dot' where to traces intersect is where you need to make connections. If they traces or lines on the scheme just go through one another without a dot, then those do NOT get connected together. Due to way component pin-outs are, it isn't that easy to simply draw them out showing exactly how things connect or not, so again the dots are where points actually get connected.

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