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Just Jeff

Composite Mod Help

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Good Afternoon,

 

I completed a composite mod on one of my 2600s and have some questions that I was hoping someone experienced with it could help me out with..  When it arrived the instructions were literally "watch one of the many videos online"  so I did that. I have not turned it on yet, mostly because I do not think it is correct.  Tracing things out on the 2600 board, I believe the yellow and blue wires are reversed.  Are they?  (The blue looks almost white in the pics.)

 

Here is a picture of the board that came with it:

20210117_125644.thumb.jpg.02e4efda027d350d78b258e5366dafcc.jpg

And here is where I connected everything from the bundle of 4 wires on the left side of the picture above which appears to be the input.  I feel like yellow and blue may be reversed.  Pins 1, 3, and 4 were used.  Pin 4 is connected to the wire labelled "Audio In" on the new board.  I feel like this should probably be video.  Should it?:

20210117_125650.thumb.jpg.9f0422b7333a0036daaa054279c31a50.jpg

 

Additionally, I put this wire on the 4th resistor from the right but my solder is bleeding onto the 3rd resistor.  Is this OK?  They look like the traces might connect them anyway.  Do they?

20210117_102212.thumb.jpg.6cb192f5bfeff2615ee5de26ebb6cef7.jpg

 

I think these are correct: Yellow is on the yellow jack, and blue is connected to the red and white jacks.  These wires came out of the right side of the new board.

20210117_125637.thumb.jpg.aa2dc0afc2b9d4dac717062ab421a969.jpg

 

 

 

Edited by Just Jeff

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I haven't done any comp mods on the 2600 as yet, but I'm pretty sure you are correct in that you have the blue and yellow reversed from the comp av board to the 2600 main board. Reverse them and test it out at that point.

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Yeah...  Re-watching the video, it looks like his yellow is connected to his Audio In on the new board which is counterintuitive I think.  He also had me snap off the RF board.  I would have much rather unsoldered the whole assembly with the shield which I saw someone do in another.

 

 

Outstanding questions:

 

Is it OK that transistors 3 and 4 are connected with solder?  I don't want to unsolder any of it if I can help it.

 

 

 

New questions: 

 

Should I have removed any resistors? In another video, I saw someone remove two but I didn't do any.  I did remove the one transistor behind the tall red thing in picture 3 (unseen)

 

My right side difficulty switch is sheared off.  Can I remove the channel selector switch and use it for a difficulty switch?  They look identical.

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On 1/17/2021 at 11:32 AM, Just Jeff said:

Good Afternoon,

 

I completed a composite mod on one of my 2600s and have some questions that I was hoping someone experienced with it could help me out with..  When it arrived the instructions were literally "watch one of the many videos online"  so I did that. I have not turned it on yet, mostly because I do not think it is correct. 

The kit you have is a very common amplifier replacement that produces a composite video signal.  I built one using the schematic and installation instructions from the following page, which I'm fairly certain is practically identical to your circuit board.

 

https://www.instructables.com/ATARI-2600-Video-Composite-mod/

 

The difference between the kit and schematic is the omission of a resistor from video-out to ground, which darkens the output signal. You can review the instructions above including which components to remove and hopefully you can resolve any discrepancies with other YouTube videos.

 

Also, I did not remove the RF modulator in my installation; no problems by keeping it in place.

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I would like to mod my Rambo clone, found this video that it works.

I just have a little different PCB revision (2600A-6192), but very similar.

I am interested in that video amplifier schema, there is one capacitor that is not on other mods for 2600, maybe it is clone specific. It is marked as 47 uF, but in the video it looks like smaller cap (47 nF or pF).

edit: now I see there are more caps in that video that are not described in the schema :)

I am not very good at electronics, so would like to know some others opinions.

1469496766_obrzok.thumb.png.d8ccf340579ff26bc2b4c4436dd3c0c5.png

Edited by Wizzard
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On 1/19/2021 at 12:55 AM, Steve Guidi said:

The kit you have is a very common amplifier replacement that produces a composite video signal.  I built one using the schematic and installation instructions from the following page, which I'm fairly certain is practically identical to your circuit board.

 

https://www.instructables.com/ATARI-2600-Video-Composite-mod/

 

The difference between the kit and schematic is the omission of a resistor from video-out to ground, which darkens the output signal. You can review the instructions above including which components to remove and hopefully you can resolve any discrepancies with other YouTube videos.

 

Also, I did not remove the RF modulator in my installation; no problems by keeping it in place.

 

Thanks I completed the mod and its got a clear picture but... Its too dark.  And I think the sound is a little weird sometimes.

 

Apparently that's very common.  I've seen many variations on how to correct it.  Yours is the first I've seen that shows that specific combination of resistors.

 

Not sure which to do.

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May AV mod help me when I have monochrome signal on my console? Is it just the modulator issue or something else?

 

It worked in colour before, I just touched something by the power adapter. Maybe I burned some chroma chip?

Edited by Wizzard

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On 1/20/2021 at 2:12 AM, Just Jeff said:

 

Thanks I completed the mod and its got a clear picture but... Its too dark.  And I think the sound is a little weird sometimes.

 

Apparently that's very common.  I've seen many variations on how to correct it.  Yours is the first I've seen that shows that specific combination of resistors.

 

Not sure which to do.

Are you using your AV upgraded system on a modern LCD display or CRT? If you are using it on a modern display, then you likely need to remove the 75R resistor that is attached from the video out to ground. On a CRT it was needed to bring the brightness down, but for some reason on most modern displays, it causes the picture to be a little too dark.

 

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The 1st thing I discovered on my 1st AV mod is that the wire colors don't neccessarily match on a lot of the kits out there. Forget about color and concentrate on verifying that the point to point mapping is correct i.e. video on the mod PCB to the video on the 7800 PCB. Refering to the schematics is a good idea as well. 

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On ‎1‎/‎22‎/‎2021 at 6:53 AM, cedropoole said:

The 1st thing I discovered on my 1st AV mod is that the wire colors don't neccessarily match on a lot of the kits out there. Forget about color and concentrate on verifying that the point to point mapping is correct i.e. video on the mod PCB to the video on the 7800 PCB. Refering to the schematics is a good idea as well. 

Exactly this. I bought mine on ebay and the instructions were to ditch the yellow wire and use the included blue one for audio. I have no idea why that was the thing, but I did not. I used yellow for video, black for ground and I don't remember the rest. The instructions are weird, but basically you don't need to use the wire that comes with it if you don't want. Just follow this advice and make sure you solder to the correct contacts.

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On 1/22/2021 at 9:37 AM, -^CrossBow^- said:

Are you using your AV upgraded system on a modern LCD display or CRT? If you are using it on a modern display, then you likely need to remove the 75R resistor that is attached from the video out to ground. On a CRT it was needed to bring the brightness down, but for some reason on most modern displays, it causes the picture to be a little too dark.

 

I've tried it on both.  The first CRT was noticeably dark, same with one of my LCDs.  I was able to do a decent adjustment another CRT, but I'd definitely like to improve the performance of the mod if possible so it works better overall.  I wish could find suggestions that also mentioned what the components (for removal) are for.

 

Are you sure about removing that resistor?  That is yet another different solution.

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If you just want to test it real quick, just clip the leg near where it is soldered down on one of the output wires and see how it looks? That way you can always apply a little dab of solder to put it back in place if it doesn't help.

 

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On 1/25/2021 at 6:36 PM, -^CrossBow^- said:

If you just want to test it real quick, just clip the leg near where it is soldered down on one of the output wires and see how it looks? That way you can always apply a little dab of solder to put it back in place if it doesn't help.

 

OK I' think I'll give it a shot.  Yours is the first suggestion I've gotten that comes with a understandable explanation of what's happening and why.  So maybe this would be a good place for a varistor/potentiometer.  What do you think?

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When I look at all those AV mod instructions, I see that we always remove some components from Atari. I wonder if it was possible to reuse them for another AV mod. There is always some transistor and a few resistors. I am sure this was answered a lot of times, I am just not aware of that.

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On 1/22/2021 at 4:32 AM, Wizzard said:

May AV mod help me when I have monochrome signal on my console? Is it just the modulator issue or something else?

 

It worked in colour before, I just touched something by the power adapter. Maybe I burned some chroma chip?

This same problem just happened to me. I have a Woody 4-switch VCS I bought from Osgeld a few years ago with the component EDIT: composite mod installed. It was working fine but had been stored for the past year or so. I just bought a Harmony and a Ranger controller after watching the RetroRGB stream, and pulled out the VCS to try them out. Surprisingly the picture was just black and white now. I thought maybe the video cable was bad, or the input on my CRT, but I verified it's the  console at fault. Would anyone have an idea of what I could look for? Maybe a bad solder point or something?

On 1/22/2021 at 5:46 AM, ChildOfCv said:

There's a B/W switch that turns off color.  Make sure it's working correctly.

How can I verify if the B/W switch is working if the picture is always black and white? I noticed when I switch it, the picture does look like it's switching... something... and I noticed the sound changes slightly as well when I do this... might that indicate a possible problem?

Edited by SpotAnime

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11 minutes ago, SpotAnime said:

How can I verify if the B/W switch is working if the picture is always black and white? I noticed when I switch it, the picture does look like it's switching... something... and I noticed the sound changes slightly as well when I do this... might that indicate a possible problem?

That does sound like it's responding to the switch, at least.  Is it a PAL or NTSC system?  Either way, first make sure your color pot has at least 7V between its 2 closest pins.

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19 minutes ago, SpotAnime said:

This same problem just happened to me. I have a Woody 4-switch VCS I bought from Osgeld a few years ago with the component mod installed. It was working fine but had been stored for the past year or so.

Did you mean component or did you mean to say composite? If you have a component mod, I'm not familiar with that one but I suspect it would use Tim's RGB board kit? Weren't there some issues with earlier done RGB 2600s lately that required something to be repaired? I recall James' 2600 was looked at and fixed by Nathan not that long ago and I had someone reach out to me last night asking about their RGB 2600 that is just displaying what looks like a sync issue on their PVM when trying to use it now?

 

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19 minutes ago, ChildOfCv said:

That does sound like it's responding to the switch, at least.  Is it a PAL or NTSC system?  Either way, first make sure your color pot has at least 7V between its 2 closest pins.

NTSC. Where do I find the color pot on the console?

12 minutes ago, -^CrossBow^- said:

Did you mean component or did you mean to say composite? If you have a component mod, I'm not familiar with that one but I suspect it would use Tim's RGB board kit? Weren't there some issues with earlier done RGB 2600s lately that required something to be repaired? I recall James' 2600 was looked at and fixed by Nathan not that long ago and I had someone reach out to me last night asking about their RGB 2600 that is just displaying what looks like a sync issue on their PVM when trying to use it now?

 

Ah I have component on the brain... I meant composite (yellow RCA). Sorry to make you write that all out for nothing... ;)

Edited by SpotAnime

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29 minutes ago, SpotAnime said:

NTSC. Where do I find the color pot on the console?

Ah I have component on the brain... I meant composite (yellow RCA). Sorry to make you write that all out for nothing... ;)

If you are only getting black and white with a composite install in place, then I would start with the color trimmer first. The color wheel adjustment is that black or white colored flat disc just to the left of the RF shielding box. Usually measure about an inch in diameter so you really can't miss it.

 

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15 minutes ago, -^CrossBow^- said:

If you are only getting black and white with a composite install in place, then I would start with the color trimmer first. The color wheel adjustment is that black or white colored flat disc just to the left of the RF shielding box. Usually measure about an inch in diameter so you really can't miss it.

 

Cool, I'll try that. Just curious though, since I said this was just sitting in a Rubbermaid bin for a year, but would display color previously - what could cause the color wheel to go out of adjustment?

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Corrosion/time...etc. The trimmer is just a variable resistor so over time corrosion can build up on them and cause the values to go out of whack. In some cases you only need to turn the wheel back and forth a few times to get that initial layer back in shape again. I tend to spritz with a little contact cleaner and then move the wheels fully back and forth a few times to be sure. I use the colorbar generator to get the color lined back up again using a CRT, but in a pinch Pitfall! is good to use as well since you know how that should look and can get a good gauge of color adjustment from that game alone.

 

But the thing is, the composite mod is only amplifying the composite signal that is being sent to the RF modulator. So if you are getting black and white, it is either the color wheel is out of whack or something else along the line of the color signal from Pin#9 off the TIA not making its way to the rest of the circuit.

 

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On 1/22/2021 at 9:37 AM, -^CrossBow^- said:

 If you are using it on a modern display, then you likely need to remove the 75R resistor that is attached from the video out to ground. 

Just curious. Is this resistor on the 2600 board and if so, where is it located? I looked at schematics and could not locate it. I have same dark outpu issue with a 4 switch that I did several months ago. Since I have a 7800 modded, I never went back to try to fix it, but this post gave me a reason.

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