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Looking for a simple Atari 5200 Composite mod

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On 1/28/2020 at 3:23 PM, Adam Mace said:

Do you happen to have a schematic of this circuit you've made?  I'm working on a 5200 and getting real bad RF interference.   I'd rather bypass it entirely without buying a UAV board, but my theoretical knowledge isn't that great.  

143245920_videoampAV.png.07402448d6278051e94ca289f883bea1.png

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On 1/28/2020 at 10:23 PM, Adam Mace said:

Do you happen to have a schematic of this circuit you've made?  I'm working on a 5200 and getting real bad RF interference.   I'd rather bypass it entirely without buying a UAV board, but my theoretical knowledge isn't that great.  

Here's a quick hand-drawn schematic. Not 100% sure about the polarity of the 0.1uF cap, or the connections to the 2N2222 / 2N3904 transistor (you should attach the transistor as per the schematic in your post).

You could also try the schematic in your post. Will be interesting to see which gives a better picture.

Disclaimer: I take no responsibility for any dead 5200's resulting from the use of this mod.

 

5200 mod curcuit.jpg

Edited by jum

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On 2/6/2020 at 5:35 AM, jum said:

Here's a quick hand-drawn schematic. Not 100% sure about the polarity of the 0.1uF cap, or the connections to the 2N2222 / 2N3904 transistor (you should attach the transistor as per the schematic in your post).

You could also try the schematic in your post. Will be interesting to see which gives a better picture.

Disclaimer: I take no responsibility for any dead 5200's resulting from the use of this mod.

 

5200 mod curcuit.jpg

Thank-you!  I understand the risks.  My board is slightly different than yours, but the points you pulled 5v and AV from still exist, so I'll give it a go.  Much appreciated.

 

You used the 2n222 right?   I see you have the 3904 mentioned as well, I've got both.  the 3904 is used in the basic 2600 mod, but the board schematic is different from what you've posted.   It's the same as the one Shawn posted above you.   I might try both, see which provides the better picture and report back.

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On 1/31/2020 at 5:06 AM, Shawn said:

143245920_videoampAV.png.07402448d6278051e94ca289f883bea1.png

This appears to be pretty much the same as the 2600/27800 composite mod.  Does this work with the 5200 as well?   I might try both this and the one below and report back.

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On 2/7/2020 at 7:13 PM, Adam Mace said:

This appears to be pretty much the same as the 2600/27800 composite mod.  Does this work with the 5200 as well?   I might try both this and the one below and report back.

Should work with the 5200. Let us know how it goes.

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13 hours ago, jum said:

Should work with the 5200. Let us know how it goes.

Where did you pull Audio from?  I got video working fine, just looking for the best spot to tap into Audio.  The pin going into the modulator?

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Reusing the spot on the board where the rf modulator came from.  So far so good.  Just need to buy more rca jacks, I've just got the one

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On 2/19/2020 at 4:12 PM, Adam Mace said:

Where did you pull Audio from?  I got video working fine, just looking for the best spot to tap into Audio.  The pin going into the modulator?

I usually pull the audio from the top of R50. I attached a 2k from the top of R50 then attached to the + lead of a 10uf cap with the - lead going to my RCA jack for audio.

 

 

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1 minute ago, -^CrossBow^- said:

I usually pull the audio from the top of R50. I attached a 2k from the top of R50 ...

You know, none of the other sources I saw when I did my UAV mod mentioned anything aside from grabbing audio from the top of R50. I thought the audio levels seems a bit "hot" but I haven't checked them with a meter or scope. I think I'll pull my system open tomorrow and install a resistor like you did. 

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5 minutes ago, DrVenkman said:

You know, none of the other sources I saw when I did my UAV mod mentioned anything aside from grabbing audio from the top of R50. I thought the audio levels seems a bit "hot" but I haven't checked them with a meter or scope. I think I'll pull my system open tomorrow and install a resistor like you did. 

Exactly why I did it! It is hot without the resistor. I use the Raster tracker test rom for the audio and without the resistor it distorts quite a bit. I haven't done this with my personal 5200 however as it didn't seem hot at the time I first modded it with the AV setup I was using back then but it I need to back in there and add one to mine in the future. 

 

I also kinda wished I didn't have the UAC at the time I did my 5200 UAV video because the audio from the UAC wasn't that great to be honest. It was out of phase by a full 180 and seemed tinny. I might have another 5200 come in soon for a UAV workup and I might just redo it.

 

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15 hours ago, -^CrossBow^- said:

Exactly why I did it! It is hot without the resistor.

Somehow I don't have any 2K resistors around, or else they're in the wrong bin in my parts cabinet. At any rate, I desoldered the audio pickup line from my 5200 at R50, soldered a 1.5K resistor to the top (back) leg of R50 and then soldered the audio line to the other end of the resistor and covered the whole thing in heat shrink. Sound is decidedly "cooler" now and much more natural sounding. :)

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1 minute ago, DrVenkman said:

Somehow I don't have any 2K resistors around, or else they're in the wrong bin in my parts cabinet. At any rate, I desoldered the audio pickup line from my 5200 at R50, soldered a 1.5K resistor to the top (back) leg of R50 and then soldered the audio line to the other end of the resistor and covered the whole thing in heat shrink. Sound is decidedly "cooler" now and much more natural sounding. :)

I'm sure that is close enough. I usually advise anything between 1k8 - 2k2. But it isn't an exact science. Again I noticed it when testing the first UAV modded 5200 I did for a client without the UAC. I have the same issue with my personal 5200 but again at the time I did my AV mod it, I was using different equipment to hook everything up and didn't notice it as I do now. The cap may not be needed but since taking it from r50 is before the poly caps to the RF modulator, I figure it wouldn't hurt to have a little more filtering in place just to be sure. Besides I have well over 100 10uf 6.3 - 25v caps laying around as spares from other cap kits over the years so might as well use them.

 

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Yeah. I already have a 10 uF filter cap on the audio line already; I was just adding the resistor to lower the signal level a bit. 

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On 2/20/2020 at 12:12 AM, Adam Mace said:

Where did you pull Audio from?  I got video working fine, just looking for the best spot to tap into Audio.  The pin going into the modulator?

See attached picture (blue wire). Looks like resistor R41 (on my 2-port 5200, I think 4-port is the same). Like the other guys say, may be a good idea to add a resistor to the audio out (although mine sounds fine and the level seems OK).

5200 audio.jpg

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I actually did a new UAV installation video with much more detail this time around specifically on a 2-port model. It was the exact same process more or less that I used with the 4-port but at least now in this video I did better testing and was able to confirm the following: (BTW Bryan also mentions this in his original outlined installation)

 

If you want to keep the RF intact alongside the UAV, then you have to keep the 4050 buffer in circuit somewhere. In my new video, I clip the small ends off the IC legs and solder the larger portions of the legs to the top of the inline header pins that get soldered to the UAV. But for most people it would likely be easier to just solder the socket that comes with the UAV Kit version to the top of the 4050 and not mess with desoldering the 4050 much less re-attaching it to the UAV in some way as I usually do.

 

If you want to remove the RF and not use it, then you can use the UAV without the 4050 as I found the weekend prior when I was doing this newest video. I also go into detail the audio wiring I do at the end starting at 24:48:

 

 

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