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Atari A/V mod update


Longhorn Engineer

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Mine fell, and now all I get is half color, as seen here:
[snip]

Is there a resistor between pin 6 and pin 9? (might be on the motherboard, might be on the mod) Check the connections there. Check everything associated with pin 9. I can't view Longhorn's schematics right now so I can't offer more detailed suggestions. Gotta go glue some more pieces to Death Race! It's getting picked up tonight for California Extreme. Soooo last minute!!!

 

I checked a bunch of things, and I'm still baffled. The Chroma line isn't getting any signal, which is the the most I could find out.

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Mine fell, and now all I get is half color, as seen here:
[snip]

Is there a resistor between pin 6 and pin 9? (might be on the motherboard, might be on the mod) Check the connections there. Check everything associated with pin 9. I can't view Longhorn's schematics right now so I can't offer more detailed suggestions. Gotta go glue some more pieces to Death Race! It's getting picked up tonight for California Extreme. Soooo last minute!!!

 

I checked a bunch of things, and I'm still baffled. The Chroma line isn't getting any signal, which is the the most I could find out.

What tools do you have available? Multimeter? Logic probe? Oscilloscope? (listed in increasing desirability)
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Mine fell, and now all I get is half color, as seen here:
[snip]

Is there a resistor between pin 6 and pin 9? (might be on the motherboard, might be on the mod) Check the connections there. Check everything associated with pin 9. I can't view Longhorn's schematics right now so I can't offer more detailed suggestions. Gotta go glue some more pieces to Death Race! It's getting picked up tonight for California Extreme. Soooo last minute!!!

 

I checked a bunch of things, and I'm still baffled. The Chroma line isn't getting any signal, which is the the most I could find out.

What tools do you have available? Multimeter? Logic probe? Oscilloscope? (listed in increasing desirability)

 

Only a mutimeter. I'm not an Electrical Engineer :P

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Mine fell, and now all I get is half color, as seen here:
[snip]

Is there a resistor between pin 6 and pin 9? (might be on the motherboard, might be on the mod) Check the connections there. Check everything associated with pin 9. I can't view Longhorn's schematics right now so I can't offer more detailed suggestions. Gotta go glue some more pieces to Death Race! It's getting picked up tonight for California Extreme. Soooo last minute!!!

 

I checked a bunch of things, and I'm still baffled. The Chroma line isn't getting any signal, which is the the most I could find out.

What tools do you have available? Multimeter? Logic probe? Oscilloscope? (listed in increasing desirability)

 

Only a mutimeter. I'm not an Electrical Engineer :P

OK. Put in Combat (I assume you have at least one copy of that) and set the BW/COLOR switch to BW. Press RESET to start the game then measure the DC voltage at pin 9 of the TIA. Do it again with with the switch set to COLOR (push RESET again).

 

Also, is there a picture of the schematic? I'm too lazy to install yet another CAD package.

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http://longhornengineer.com/images/atarivi...Mod%20V2_2E.pdf

 

There's the schematic

 

Oddly enough, I got a reading of .17 volts on Black and White, and .10 on color.

Ok, schematic helps. Thanks. Interesting way of doing the color. And pretty much unbuffered. That's a surprise.

 

I expected the readings to be different. And the color setting should be lower. So that's good. Am I correct in stating that you have color, it's just very washed out? If so, the 680 Ohm resistor between pin 9 and the CD4050 is suspect. Check the connections there. Also measure the DC voltage on pin 12 of the CD4050 (for color and bw settings). I would expect maybe 3.5V. Very roughly.

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  • 1 month later...
  • 1 month later...

G'day Longhorn,

Excellent job on the MODs and showing us the screenshots of how good and clear the pics are on the 2600.

 

I was looking on another topic that you'd never tried the MOD on a PAL format Atari.

If I still had the 4 switcher woody PAL verison, I could've Bought one off you, and installed it into my PAL Woody and get back to you to show proof.

 

But yer, I just might order one from you in a week or two and install it on my NTSC 4 Switcher oody since I got one here that's an American NTSC output and I live in Australia, I got that American Cosnole one working here in AUS.

 

Great pic views once again. icon_thumbsup.gif

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Hello everyone. Sorry for going MIA on everyone. The combination of getting on Hack-A-Day and Benhecks website really put my order filling on overload. To date there has been over 300 mods shipped worldwide. The volume is slowing down so I am able to breath a bit and get to work on that 7800 mod I have been eyeing on my work bench. It seems something went wrong on the back end of my website about a month ago and all my website email fell into a black hole. This has been fixed but I can't recover any emails lost in that time frame. If you sent me an email within the last month please resend it again.

 

Parker

 

 

PS- Special update tonight...I hope ;)

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glad your back, was getting worried

 

Thanks Mimo, sorry everyone got worried.

 

Updated the 2600 4-switch install guide. Has a more universal pinout so people with different board revisions should be able to install the mod. Also, thanks to tremoloman2006 there is an install guide for the Sears Video Arcade II.

 

Updated 4-Switch Install

New Sears VAII Install

 

I am hoping to revamp the heavy sixer install and add a lite sixer soon. The heavy is currently the hardest to install for because you have to juggle the shielding around. I figured out a new way to install it so it will be easier.

 

Parker

Edited by Longhorn Engineer
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I first want to say thanks, Longhorn Engineer. Last night I installed one of your preassembled video mods in my 4-switcher, and the difference between the before and after is night and day. Simply beautiful. I am now doubly excited about the possibilities while I wait for a Harmony cart.

 

Also a tip to installers. If you don't have the recommended non-biting type of drill bits, run the drill in reverse for hole diameters greater than 1/8. This gently shaves the plastic away, and it doesn't take much longer than normal on the relatively thin plastic.

 

This worked well for the standard bit I used for the 1/4 holes, and with this method I was even able to use a wood-boring bit for the 1/2 hole and it came out nice and clean!

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  • 1 month later...
<br />Hi there LE,<br /><br />Any news for us PAL-sters?<br /><br />I've got two woodies here ready for the treatment.<br /><br />Thanks.<br />
<br /><br /><br />

 

I've asked LE that question a month or two back, He has tested it on a PAL 2600, It did work but there was some kinks he needs to work out before he will start selling them the last time I'd heard. I'm still waiting for the e-mail from Paypal when my A/V mod from LE will be shipped as I paid for mine in Sept-Oct and still waiting. :)

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  • 2 weeks later...
Pretty much anything that's a light or pastel color comes out very dim, no matter the game. And the problem persists whether the console is connected to an LCD or CRT TV.

I made 2 changes to mine that may fix this problem.

 

I just installed my first board tonight in a 4-switch & found things were too bright on s-video & composite. Color Bar Generator confirmed that the first 3 bars on the greyscale screen were the same intensity which kills off a lot of detail.

 

The fixes for s-video were:

Remove 75 ohm resistor that runs above the FMS6400

Increase resistance on 75 ohm to the right of FMS6400 to about 150ohms

 

I haven't messed with the composite side but I'll bet it's about the same.

 

Anyway, after these two changes, the s-video appears spot-on.

 

LHE were you able to test this out? What were your results?

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Pretty much anything that's a light or pastel color comes out very dim, no matter the game. And the problem persists whether the console is connected to an LCD or CRT TV.

I made 2 changes to mine that may fix this problem.

 

I just installed my first board tonight in a 4-switch & found things were too bright on s-video & composite. Color Bar Generator confirmed that the first 3 bars on the greyscale screen were the same intensity which kills off a lot of detail.

 

The fixes for s-video were:

Remove 75 ohm resistor that runs above the FMS6400

Increase resistance on 75 ohm to the right of FMS6400 to about 150ohms

 

I haven't messed with the composite side but I'll bet it's about the same.

 

Anyway, after these two changes, the s-video appears spot-on.

 

LHE were you able to test this out? What were your results?

 

I have not seen this issue pop up on my end but ill see what happens tonight. I have a atari I been needing to mod.

 

Parker

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I'm wondering if ASEL on the FMS6400 should be low. Does luma really need the 6dB gain? How does it look without the above changes, but with ASEL tied low? I would think this would be ideal as the FMS chip runs hot; lowering the gain should cool it off a bit.

 

I should have some time tonight to do a few more experiments.

 

I'm also wondering if anything ever came of this experiment.

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