Let's design a new video mod

[+batari]

Did you use batchpcb? When did you put the order in? Just curious about turn around times.

Yes, I used batchpcb. It usually takes 3-4 weeks. It has never taken less than three weeks or more than five. I placed the order on 2/19 after finishing a couple of SMT versions of the mods.

Edited March 11, 2011 by batari

[+batari]

Got the boards and the parts today, and assembled a board. I initially had an issue with the pots (they have pointy things on the legs which made contact with the ground plane on the board) but once this was resolved, the board worked fine. No vertical lines, so looks like RF was the issue. Here is the board:

 

 

The display looked best with the contrast pot on 0 ohms (though I like a high contrast picture, others may not). The brightness looked best at around 200 ohms.

 

The brightness pot size may need changing and a series resistor may need to be added as it caused problems when turned too far. If turned too dim (too low resistance) the picture would become noisy (could be the cause of LittleJoe's issues) and if turned further, the TV would lose sync. Too bright and horizontal bars began to appear across the screen.

 

Here are pics of the grayscale, colorbars and a close-up of the title screen text for comparison with earlier images. This is composite. Sorry about the moire patterns - for some reason the moire from my camera was really bad today. Not sure why.

[Game-Tech.US]

Excellent, I ordered a couple boards of my own without the pots.

I was able to squeeze it down to 1"x1.3" and 1.5"x1.3" with pause components.

[keilbaca]

Amazing work!

 

Do you plan on building a batch of these for us to buy?

[+batari]

Yes - just need to add another jumper (for mono/stereo), change the footprint for the pots and add a resistor in series with the brightness pot. Also, need to work up some installation instructions.

[LittleJoe]

Yes - just need to add another jumper (for mono/stereo), change the footprint for the pots and add a resistor in series with the brightness pot. Also, need to work up some installation instructions.

 

I finally put pots on my experimenters board build, and it looks excellent, except for a little vertical rf striping. But I don't have the ground plane so that's to be expected. Is there anything I can do to improve the RF situation on an experimenters’ board?

 

If I can help with some of the grunt work on the installation instructions please let me know.

[+batari]

Yes - just need to add another jumper (for mono/stereo), change the footprint for the pots and add a resistor in series with the brightness pot. Also, need to work up some installation instructions.

 

I finally put pots on my experimenters board build, and it looks excellent, except for a little vertical rf striping. But I don't have the ground plane so that's to be expected. Is there anything I can do to improve the RF situation on an experimenters’ board?

 

If I can help with some of the grunt work on the installation instructions please let me know.

If you want to help with instructions, I will send you a board with a few parts (such as the S-video jack and composite/audio jacks I am using, since those will be needed for drill templates anyway.) Also, you can evaluate the board with the ground plane. PM me your address and I'll send it out (probably next Monday until I'll be able to, so no rush.)

[Game-Tech.US]

I got my Batari prototype boards in today.

Currently testing on a 2600JR. I cut the appropriate resistors for pins 6, 9, 12, and 13.

19" LCD with all video setting set at exactly half:

Svid pics: 1, 2, 3, 4, 5, 6.

Comp pics: 1, 2, 3, 4.

Obviously comp is worse, but there's jaggedness of the rainbow next to the atari logo, everything seems a little blurry, a few places where black seems to extend left of the picture, and what looks like vertical interference bars, but in a wider pattern if in a pattern at all.

Svid would be damn near perfect but there are very noticeable solid vertical bars all the way from right to left.

I couldn't get a single good photo of the 19" CRT vid out, but it's way better than the lcd comp, and the bars are there like the lcd's svid just less noticeable which gives it a little advantage over the lcd svid, but still has the typical crt comp drawbacks. Also noticed the pants on the wobble legs guy are green on the crt but on the lcd svid he seems to be all brown.

I tried two a/c adapters, both 9v, didn't matter.

Also, the audio is way too loud and scratchy, maybe 1.8Ks instead of 1.5Ks would help both issues or should we try electro caps again instead of ceramics?

I also went back and hooked up my LE prototype board to compare and found the LE board's blacks are overbearing, the ladders and rocks that block a path in PF2 are hardly visible and what should be a brown tree is a black tree, and its impossible to separate the green's of the tree tops and regular background by adjusting the main color pot of the JR.

So now I prefer the Batari board, but its still not 'perfect.' Get rid of the vertical lines on the svid then you'd have a great board.

Also, i'm not going to say it isn't my board layout causing interference, i'm new to pcb design. I do have the proper caps in the proper places. I am using the fms6406 and pin 2 is not connected to anything. I also have power plane on top and ground plane on bottom.

Maybe I just crammed it all together too much?

Have to admit, even though i'm ready to have a final board revision, this is still a lot of fun!

[+batari]

PM me and I'll send you one of my boards to see if it has the same issue with vertical lines.

 

Audio could be due to the use of 0.1uF caps instead of 1uF. I didn't think it mattered too much but it might.

[Thomas Jentzsch]

Any chance for a PAL version when it is finished?

[+batari]

Any chance for a PAL version when it is finished?

The circuit should work in PAL as-is. Connect pins 2, 5, 6, 7, 9, and 13 from the PAL TIA to the holes marked 2, 5, 7, 8, 9, and 13 on the board, respectively. Do not connect the holes marked 6 and 12. Then, omit R1, R2, R7, and C4.

[+batari]

I just realized that the latest schematic I posted was the one with a transistor, which caused red bleed and didn't fix anything. I hope nobody is using that schematic.

 

So to clear things up, I'll post the latest, which I haven't had produced yet, but differs from the boards I had madeby just one resistor (R17) that I added so the brightness pot wouldn't screw up the picture when turned too far.

 

Other changes are the brightness pot (R13) should be reduced to 470 ohm and there may be changes to audio (most likely 1 uF caps instead of the 0.1 uF as shown.)

[+Mitch]

I was able to squeeze it down to 1"x1.3" and 1.5"x1.3" with pause components.

 

Just noticed this. Were you able to do the video blanking while pause is enabled?

 

Mitch

[Uzumaki]

I've tried a simple pause some years ago but I could only hold for a couple seconds before TIA "dies" and crashes 2600 console. You'd need a separate clock generator for TIA video to maintain sy6stem while freezing CPU. I've never bothered to check further in this as it'd be easier to implement software pause into game.

[+SpiceWare]

Pausing the Atari was figured out last year. There's now a Pause Kit in the AA store.

[Game-Tech.US]

I was able to squeeze it down to 1"x1.3" and 1.5"x1.3" with pause components.

 

Just noticed this. Were you able to do the video blanking while pause is enabled?

 

Mitch

What do you mean by video blanking?

[Game-Tech.US]

I've tried a simple pause some years ago but I could only hold for a couple seconds before TIA "dies" and crashes 2600 console. You'd need a separate clock generator for TIA video to maintain sy6stem while freezing CPU. I've never bothered to check further in this as it'd be easier to implement software pause into game.

I've used the pause mod by Trucco on both the JR and the Gemimi succesfully, haven't tested it on any other system, but no reason to believe it wouldn't work just as slick on all others as well.

[Game-Tech.US]

Started playing with the audio circuit, still using the same JR.

First I switched the 1.5K resistors for 1.8Ks like LHE uses, no noticeable difference in volume or quality.

Then I switched the .1uF ceramic caps for 1uF electrolytics, no difference in volume or quality.

Then I switched the resistors out with a few different values and still no noticeable change in volume.

So I put a 2K pot in place of each resistor and was able to bring it down to what felt like the right volume level.

This ended up being 560 ohms on each pot so I put a real 560 in place of each pot and it still sounded right.

BTW a higher ohm resistor increases volume level and lower ohm resistors decrease volume levels, no resistor and 0ohms results in no sound.

Then I put the .1uF caps back in and still heard no difference in quality.

This is good new as far as i'm concerned, electros just take up so much realestate on the board as well as add a lot of heigth.

I also used two different power supplies, a switching 9v and a linear 9v, and hear no difference in quality.

It could be this JR has other problems causing the audio to have more static or is PF2 not a good cart to use as an audio test cart?

Is there an audio test rom? (too lazy to look around)

[Game-Tech.US]

I went back and retested my LHE modded JRs. I currently have two with that circuit hooked up, two because one has just the a/v board and separate pause board and one has an a/v-pause combo board.

Anyway, I hooked up the other JR and its video was just as good as the Batari circuit. So, I spoke too soon about the black/brown problem, THAT JR had the w3 jumper pulled and was causing the issue, soldered a jumper back in and now it looks great. That jumper is for TIA pin 8.

Also, hooked it up to the 19" LCD, svid has the same problem bars as the Batari board, so it may just be the tv or it may be both of my board designs are causing the problems.

I hope to get my own Batari made board to compare to soon.

[+batari]

Started playing with the audio circuit, still using the same JR.

First I switched the 1.5K resistors for 1.8Ks like LHE uses, no noticeable difference in volume or quality.

Then I switched the .1uF ceramic caps for 1uF electrolytics, no difference in volume or quality.

Then I switched the resistors out with a few different values and still no noticeable change in volume.

So I put a 2K pot in place of each resistor and was able to bring it down to what felt like the right volume level.

This ended up being 560 ohms on each pot so I put a real 560 in place of each pot and it still sounded right.

BTW a higher ohm resistor increases volume level and lower ohm resistors decrease volume levels, no resistor and 0ohms results in no sound.

Then I put the .1uF caps back in and still heard no difference in quality.

This is good new as far as i'm concerned, electros just take up so much realestate on the board as well as add a lot of heigth.

I also used two different power supplies, a switching 9v and a linear 9v, and hear no difference in quality.

It could be this JR has other problems causing the audio to have more static or is PF2 not a good cart to use as an audio test cart?

Is there an audio test rom? (too lazy to look around)

Pitfall II sounds a bit scratchy on my unmodified console - I believe it's due to the way it generates the music (the timing is not completely consistent, probably leading to high-frequency static.) It's possible that by using the 560 ohm, you've effectively made a low pass filter. I may be wrong on that - I'll look into it later.

I went back and retested my LHE modded JRs. I currently have two with that circuit hooked up, two because one has just the a/v board and separate pause board and one has an a/v-pause combo board.

Anyway, I hooked up the other JR and its video was just as good as the Batari circuit. So, I spoke too soon about the black/brown problem, THAT JR had the w3 jumper pulled and was causing the issue, soldered a jumper back in and now it looks great. That jumper is for TIA pin 8.

Also, hooked it up to the 19" LCD, svid has the same problem bars as the Batari board, so it may just be the tv or it may be both of my board designs are causing the problems.

I hope to get my own Batari made board to compare to soon.

Did you get red bleed from the LHE circuit? This is very noticeable on my plasma TV, especially with the small white copyright text on the Test Pattern title screen. The smaller white text appears yellow due to the bleed. This is on a Jr.

 

Anyway, I will be heading to the post office tomorrow.

[+Mitch]

I was able to squeeze it down to 1"x1.3" and 1.5"x1.3" with pause components.

 

Just noticed this. Were you able to do the video blanking while pause is enabled?

 

Mitch

What do you mean by video blanking?

 

The original clone 2600 that the pause mod was reversed engineered from also included a way to blank the screen so you didn't see the video garbage on screen while it was paused. I believe this was mentioned in the original thread.

 

Mitch

[Game-Tech.US]

I was able to squeeze it down to 1"x1.3" and 1.5"x1.3" with pause components.

 

Just noticed this. Were you able to do the video blanking while pause is enabled?

 

Mitch

What do you mean by video blanking?

 

The original clone 2600 that the pause mod was reversed engineered from also included a way to blank the screen so you didn't see the video garbage on screen while it was paused. I believe this was mentioned in the original thread.

 

Mitch

Then no, I didn't even know such a thing was possible! It would be even better if it put up a screen or just text letting you know your atari is paused! Dream on, right?

I'll have to look over the original thread sometime, I found out about the pause from trucco's site, never read about it here. Such a thread should be stickied...

[Game-Tech.US]

Did you get red bleed from the LHE circuit? This is very noticeable on my plasma TV, especially with the small white copyright text on the Test Pattern title screen. The smaller white text appears yellow due to the bleed. This is on a Jr.

 

Anyway, I will be heading to the post office tomorrow.

I should prolly build a Test Pattern cart so I can properly test and report.

[bircoe]

batari, the pics in post #77 look fantastic... Excellent work!

 

Was that with ML6428CS1X or FMS6400?

 

How do I get some boards, do you have any spare? how much do you want for say 3-5?

 

I've managed to source some FMS6400CS1X's through digikey to build some LHE mods, are the FMS6400 and ML6428CS1X interchangeable?

[+batari]

I think it was a FMS6406. I have a half-built board that uses a ML6428 but have been a bit busy lately.

 

The 6400 is interchangeable with the 6428. The 6406 and 6410 are the same except for pin 2. I put a jumper on my board to allow either chip.

 

Eventually I do plan to make some boards available but for now I only have a few on hand. I will repost when that day comes.

Edited April 20, 2011 by batari