Atari 400 A/V mod

[xrbrevin]

Does anyone know of a convenient A/V mod for the Atari 400?

The ones I found require extra components and a home-made PCB which i would rather avoid if poss.

 

A post on the following thread on here stated that prior to the RF modulator, the signal should be composite:

My machine has the RF modulator on a separate PCB connected via a pin-header so in theory it should be quite a clean/straightforward process - remove the modulator and wire the composite signal pin along with ground to a phono plug.

Does anyone have any experience of wiring it up?

Cheers!

 

[TGB1718]

You would also have to have a plug/socket for Audio too

[mimo]

https://www.atarimagazines.com/v3n1/littlebrother.html

 

 

But I was never very successful with this one.

 

UAV or SCCC would be my preference, both cost though 

[xrbrevin]

yes, i dont fancy that. if i was inclined to add any components id add a UAV device

but id rather just mod whats already there if poss

[+DrVenkman]

5 minutes ago, xrbrevin said:

yes, i dont fancy that. if i was inclined to add any components id add a UAV device

but id rather just mod whats already there if poss

That's all well and good but the point is you will have to add something for audio if you're not using RF on a 400.

[xrbrevin]

1 minute ago, DrVenkman said:

add something for audio

do you mean a cable or socket?

i accept that but i havent decided which yet

theres already an extra hole in the back panel so i may just rig up a 5-pin DIN to match the other models. then i can use the same cable

i just gotta track down the right connections on the board in order to proceed

[+DrVenkman]

4 minutes ago, xrbrevin said:

so i may just rig up a 5-pin DIN to match the other models. then i can use the same cable

i just gotta track down the right connections on the board in order to proceed

@flashjazzcat has done at least one Youtube video on this very thing for a 400. If you haven't seen it, look it up and give it a watch. 

[xrbrevin]

nice one, ill check it out ?

[+slx]

9 hours ago, xrbrevin said:

Does anyone know of a convenient A/V mod for the Atari 400?

The ones I found require extra components and a home-made PCB which i would rather avoid if poss.

 

 

Check out tfhh's SCCC (Super Color CPU Card). It includes UAV and audio mod and is very easy to install.

[+Nezgar]

11 hours ago, slx said:

Check out tfhh's SCCC (Super Color CPU Card). It includes UAV and audio mod and is very easy to install.

Here is the link to tf_hh's document detailing the products, including the SCCC:

http://www.van-radecke.de/STUFF/tfhh_HW_info.pdf

 

Can be seen in this video:

 

[xrbrevin]

hi,

thanks, i shouldve mentioned in my first post but my other 400 has tfhh's SCCC and 48k/52k boards. brilliant though they are, i wanted this other machine to have a different mod. it already has the 32k piggyback RAM mod so a simple A/V solution is the next objective

u shall do some pioneering in this field after the retrobrighting is completed and report my findings ?

[+slx]

22 hours ago, xrbrevin said:

i wanted this other machine to have a different mod. it already has the 32k piggyback RAM mod so a simple A/V solution is the next objective

u shall do some pioneering in this field after the retrobrighting is completed and report my findings ?

That's the spirit!

[xrbrevin]

as per the link in my 1st post, i lifted R164 and connected the remaining luma/chroma signal to the composite in on my screen - see 2x pics. the result is no good. i also lifted R171 to separate luma and chroma but still no good. (is composite comprised of a mixture of both of these or just one?)

...so there is more to it than that. other articles have used the 2600 composite mod with successful results (this seems the least invasive: http://blog.tynemouthsoftware.co.uk/2018/10/atari-400-composite-video-mod.html?m=1) so maybe the 400 is missing some amplification circuitry. maybe atari left these out knowing they wouldnt be needed in an RF modulator arrangement?

anyhoo, i then connected the lifted side of R164 to audio-in on my screen but no joy there neither

 

as a secondary issue, this 400 had no audio at all when i got it so i checked out the various resistors and reflowed a few joints but still no audio. i popped the lid off the RF modulator and saw a charred looking cap but there was nothing i could do to make the audio work.

i then dug out my other 400 (NTSC variant, fitted with the SCCC) and it has a different modulator on the power board - i.e. not connected via a 5-pin header. so i switched the entire power board between the machines and voila - it now has audio! ? the NTSC 400 doesnt need the modulator as it has the SCCC so both are fully functional.

the NTSC modulator required the screen to be retuned to channel 3 but the image is pretty decent for an RF signal - see pic.

 

 

Edited February 25, 2020 by xrbrevin
added a link

[jamm]

If you're still interested in a simple S-video mod for the 400, the @flashjazzcat video @DrVenkman refers to above is this:

 

The mod he performed in that video is discussed here:

 

[jamm]

2 hours ago, jamm said:

If you're still interested in a simple S-video mod for the 400, the @flashjazzcat video @DrVenkman refers to above is this:

 

 

Well, never mind.  After studying the information more closely, it looks like some kind of small PCB was required.  This isn't obvious in @flashjazzcat's video or even in the source discussion of @Kjmann's original upgrade.

 

 

[flashjazzcat]

2 hours ago, jamm said:

 

Well, never mind.  After studying the information more closely, it looks like some kind of small PCB was required.  This isn't obvious in @flashjazzcat's video or even in the source discussion of @Kjmann's original upgrade.

What small PCB? I made the modification in the video using only wires and some passive components. There is no obfuscation in the video.

[xrbrevin]

1 hour ago, flashjazzcat said:

I made the modification in the video using only wires and some passive components

is there a summary/guide available?

cheers

[flashjazzcat]

21 minutes ago, xrbrevin said:

Is there a summary/guide available?

cheers

I think I simply followed the instructions in the KJMann thread linked above. I may well have left a link in the video description as well.

 

EDIT: No link in the description, but I point out in the comments that I gathered the info by searching this forum.

Edited February 26, 2020 by flashjazzcat

[jamm]

4 hours ago, flashjazzcat said:

What small PCB? I made the modification in the video using only wires and some passive components. There is no obfuscation in the video.

I came to that conclusion last night because I tried to follow the discussion all the way back to Kjmann's original mod instructions.  But maybe I went too far.  Here's a new summary now that I look at things again:

• [2/2013] @Magic Knight modified his 400 based on @Kjmann's S-Video mod
  • He provides a download link to a ZIP file with some instructions
    • Thanks to archive.org, the otherwise broken link is retrievable
    • The ZIP file has a couple of pictures and some very simple instructions on connecting some points on the 400 to S-video output
  • The instructions he provides on handling audio are simply:
    • "Use a wire from the audio tap on kjmanns picture and locate the earth points shown (theres plenty others on the board) you can then use the audio tap for the signal and the ground from the various points."
  • @Awch Asks for clarification, as he believed Kjmann's mod required a PCB, but Magic Knight's instructions don't specify one
  • Magic Knight explains that he found both a mod that requires a PCB and also "the more direct motherboard method."
    • The PCB mentioned is simple enough that it can be (optionally) eliminated and done without if you only need S-video and don't care about composite
    • A link (also broken) is provided to Kjmann's site. The page linked provides ZIP files with original installation instructions for different Ataris. The 400-specific ZIP is the same as the one Magic Knight linked to above.
• [4/2011] Kjmann's original instructions for installing his mod (requiring a PCB) in 400s
  • He includes a link to a forum-embedded ZIP that is no longer available (and not retrievable via archive.org)
  • Embedded pictures in the discussion are also missing.  Looks like attachments in this forum are missing when going back this many years.
• [11/2009] Kjmann's original instructions for the mod before he'd created instructions specifically for the 400
  • Again, all embedded pictures/attachments are gone

 

So Kjmann's original mod did call for a PCB, but Magic Knight provided instructions for a simpler, non-PCB version that only provides S-video output. More recent threads started by Magic Night all make use of a PCB, which is why I assumed I actually just missed a "hidden" PCB in his thread started in 2/2013.

 

If audio can be provided for this mod with a simple connection to the point indicated in Kjmann's mod pictures, why does UAV require a separate board to handle audio on the 400?

 

Edited February 26, 2020 by jamm

[flashjazzcat]

13 minutes ago, jamm said:

Another historical link is provided to Kjmann's site. This simply provides a page including the ZIP already mentioned above

That's the documentation I followed. It requires only passives, video jack and some wires to get Y/C video and audio out of the machine.

 

KJmann's 's-video boards' as I remember them were tiny PCBs with complex-looking, meandering traces on them which basically did nothing more than connect a pair of passive components between points A and B. The exact same result can be accomplished by architectural soldering.

13 minutes ago, jamm said:

If audio can be provided for this mod with a simple connection to the point indicated in Kjmann's mod pictures, why does UAV require a separate board to handle it?

UAV replaces the entire analog video circuit with modern components which deliver video output on a completely different plane, but it has nothing to do with audio. What you may want to purchase is @tf_hh's 'Super Color CPU Card', which incorporates UAV on a CPU board which plugs right into the slot on the 400/800, completely replacing the original CPU PCB. SCCC does (optionally) provide superior audio, but you are not obliged to use it. I cannot recommend SCCC highly enough for 400/800 machines.

 

I install one here:

 

Edited February 26, 2020 by flashjazzcat

[+DrVenkman]

12 minutes ago, jamm said:

why does UAV require a separate board to handle audio on the 400?

It doesn’t. UAV has ZERO to do with audio whatsoever. Some people don’t understand that, apparently. For computer systems with a dedicated DIN jack, audio continues to work as it always has. For those WITHOUT a video DIN (NTSC 600XL’s, 400’s, 2600’s, 5200’s and 7800’s), a separate audio out connection must be made. Usually that involves an RCA jack for the audio, a ground, and a small filtering cap between the two to eliminate any ground hum noise. It might also include a resistor to limit audio levels from the jack.  That’s it. Nothing in that requires a separate audio board, though Bryan created one years ago to help simplify the process for some folks. I don’t think that “UAC” board is currently available and I have no experience using it (with UAV installations in a 2600, 5200 and 7800 of my own that I performed myself).

[jamm]

1 minute ago, DrVenkman said:

It doesn’t. UAV has ZERO to do with audio whatsoever. Some people don’t understand that, apparently. For computer systems with a dedicated DIN jack, audio continues to work as it always has. For those WITHOUT a video DIN (NTSC 600XL’s, 400’s, 2600’s, 5200’s and 7800’s), a separate audio out connection must be made. Usually that involves an RCA jack for the audio, a ground, and a small filtering cap between the two to eliminate any ground hum noise. It might also include a resistor to limit audio levels from the jack.  That’s it. Nothing in that requires a separate audio board, though Bryan created one years ago to help simplify the process for some folks. I don’t think that “UAC” board is currently available and I have no experience using it (with UAV installations in a 2600, 5200 and 7800 of my own that I performed myself).

 

The reasons I assumed UAV required an audio board (not directly, but as an indirect result of not using the RF output):

• In @MacRorie's UAV Rev D thread, he says:
  • "My next step is the 400.  I have two sitting here for installation. However, I need to test the audio prototypes I made.
• The Brewing Company's product page for the UAV has on option specifically for 400s:
  • "Atari 400 all-in-one kit!  This gives you a plug-in UAV, an internal audio board, AND a BoBby!  The internal audio board will give you audio out capabilities that you lose (through no longer using RF)"

At least for me, those two bits of information strongly suggest you can't get audio out of a 400 that's had its RF removed unless you're using one of the audio boards.

 

Thanks for clearing up that situation!

 

 

[jamm]

36 minutes ago, flashjazzcat said:

What you may want to purchase is @tf_hh's 'Super Color CPU Card', which incorporates UAV on a CPU board which plugs right into the slot on the 400/800, completely replacing the original CPU PCB. SCCC does (optionally) provide superior audio, but you are not obliged to use it. I cannot recommend SCCC highly enough for 400/800 machines

 

I've also been considering the SCCC (especially since I'm planning on getting @tf_hh's RAM board for the 400 anyway), but I'm wondering if there's a noticeable improvement in the video quality over the UAV.  From reading over the (many) different threads, it seems the UAV does the same thing the SCCC does (in fact, the SCCC directly includes the UAV circuit) but simply requires a bit less soldering.  It seems the primary motivation for the SCCC was to provide an S-video output with a minimal amount of modifications to the 400.

tf_hh originally says:

Quote

I gave a promise to an ABBUC member to make a video-out solution for his Atari 400 without the need of changing parts, scratching conducting paths or any other destructive mod to his Atari 400.

Ironically, the SCCC results in replacing the entire CPU PCB, which some might see as a pretty significant change relative to the UAV's addition of a tiny PCB.  Is the video improvement noticeably greater?

 

Note that I'm planning on modding my 800 with a Sophia, so I'm definitely not apposed to making modifications if the results are worthwhile!

 

For that matter, is there an appreciable difference between the UAV output and that of @Kjmann's very simple mod described in this thread?

 

Edited February 26, 2020 by jamm

[+DrVenkman]

20 minutes ago, jamm said:

At least for me, those two bits of information strongly suggest you can't get audio out of a 400 that's had its RF removed unless you're using one of the audio boards

Those suggestions are just that - suggestions. You can grab audio and video signals completely independently of whatever the RF modulator does, doesn’t do, or whether it’s installed at all.  @MacRorie may be including his audio board with UAVs intended for 400’s as a convenience, but it’s not a necessity. 

[flashjazzcat]

11 minutes ago, jamm said:

Is the video improvement noticeably greater?

I'd expect SCCC video quality to be identical to that of UAV, since SCCC incorporates UAV. SCCC's advantage is ease of installation, compatibility with 6502 and 6502C processors (by way of jumpers on the board), and improved audio output if required.

13 minutes ago, jamm said:

For that matter, is there an appreciable difference between the UAV output and that of @Kjmann's very simple mod described in this thread?

UAV/SCCC video output is miles ahead of the KJMann mod, and you get composite and s-video in one mod (you can home-brew composite and s-video on the same 400, but it becomes complex when you try to isolate the two signal paths in order to avoid signal degradation/interference; this is all done for you with UAV/SCCC).