827 replies to this topic

[SoundGammon]

Longhorn Engineer, on Thu Dec 10, 2009 12:06 AM, said:

Worked on the 7800 video mod today. I was able to remove all the vertical lines that where an issue but the bleeding is still an issue. After removing the OR-chip to "speed" up the Luma signal the Chroma still looks like its in front it. More testing is needed to see what the issue is. I will bring it to the lab over the weekend and see where the signals are lining up.

Hi,
Where are you taking the chroma feed from? Did you try taking it from between L1 and C8. I believe L1 delays the chroma signal before it gets to the summary that feeds the RF mod unit. Could be the cause of your color bleed.

[Longhorn Engineer]

SoundGammon, on Sun Dec 13, 2009 12:50 AM, said:

Longhorn Engineer, on Thu Dec 10, 2009 12:06 AM, said:

Worked on the 7800 video mod today. I was able to remove all the vertical lines that where an issue but the bleeding is still an issue. After removing the OR-chip to "speed" up the Luma signal the Chroma still looks like its in front it. More testing is needed to see what the issue is. I will bring it to the lab over the weekend and see where the signals are lining up.

Hi,
Where are you taking the chroma feed from? Did you try taking it from between L1 and C8. I believe L1 delays the chroma signal before it gets to the summary that feeds the RF mod unit. Could be the cause of your color bleed.

I lift the MARIA and TIA pin off the board that feeds the chroma so I get zero interference from anything down stream. I already figured out what was wrong and fixed it.

[Longhorn Engineer]

Ransom, on Thu Dec 3, 2009 8:16 AM, said:

Longhorn Engineer, on Wed Dec 2, 2009 6:28 PM, said:

I ordered the parts so next week I will be able to test a full fledge 7800 mod. Then its off to 5200 and PAL land.

Glad to hear it!

Any thoughts on the resistor change on the 2600 mod, as mentioned up the thread?

Yah I tried that and I couldn't see anything on my screen. Way to dark.

[Ransom]

Longhorn Engineer, on Sun Dec 13, 2009 10:24 AM, said:

Ransom, on Thu Dec 3, 2009 8:16 AM, said:

Longhorn Engineer, on Wed Dec 2, 2009 6:28 PM, said:

I ordered the parts so next week I will be able to test a full fledge 7800 mod. Then its off to 5200 and PAL land.

Glad to hear it!

Any thoughts on the resistor change on the 2600 mod, as mentioned up the thread?

Yah I tried that and I couldn't see anything on my screen. Way to dark.

Okay. Thank you for trying!

I've found a good setting on the TV now. The lighter colors are a little washed out, but everything shows up. I had it set to have a really dark black, which made the brighter colors pop really nicely. But anything dark (such as the shots you fire in the mothership stage of Phoenix) was almost impossible to see. I lightened it up so that black is a bit greyish, and now the darker objects are clearly visible. But, as I mentioned, the pastelish colors look sort of washed out.

For reference, my modded 800XL's output (Bob Woolley's mod published in Atari Classics magazine) looks wonderful with the old setting. Everything clearly visible, nothing washed out. But that's a different machine, and perhaps the 2600 just can't do that no matter what.

Thanks again for trying!

Edited by Ransom, Sun Dec 13, 2009 10:34 AM.

[thebiggw]

Longhorn Engineer, on Sat Dec 12, 2009 11:40 PM, said:

Atari 7800 mod V2.1 image

If anyone wants to attempt to make a breadboard version of this mod please do. Unlike the 2600 mod this mod which wasn't to bad to make a breadboard version this mod has two extra SMD chips to deal with. Technically you can leave out the OR chip and the Chroma switcher if you want to do just the 7800 side. I would like atleast one other person make this mod and report that it works before I go off and order PCBS.

Ill post the schematic file tomorrow. After my finals (have one on Monday and Tuesday) I will whip up the PCB layout and then order 100 boards.

I am on vacation starting the 24th, if you post a parts list and where to get the signals from I'll be glad to get the parts ordered and test it out.

-Grant

[Longhorn Engineer]

thebiggw, on Sun Dec 13, 2009 11:10 AM, said:

Longhorn Engineer, on Sat Dec 12, 2009 11:40 PM, said:

Atari 7800 mod V2.1 image

If anyone wants to attempt to make a breadboard version of this mod please do. Unlike the 2600 mod this mod which wasn't to bad to make a breadboard version this mod has two extra SMD chips to deal with. Technically you can leave out the OR chip and the Chroma switcher if you want to do just the 7800 side. I would like atleast one other person make this mod and report that it works before I go off and order PCBS.

Ill post the schematic file tomorrow. After my finals (have one on Monday and Tuesday) I will whip up the PCB layout and then order 100 boards.

I am on vacation starting the 24th, if you post a parts list and where to get the signals from I'll be glad to get the parts ordered and test it out.

-Grant

I would have ordered the PCBs by then but I will post the parts list sometime this week. All the signals are labeled on the schematic. (U3 - 1) = (Chip U3 on the 7800 - Pin 1)

[Mitch]

Longhorn Engineer, on Sun Dec 13, 2009 12:59 AM, said:

I lift the MARIA and TIA pin off the board that feeds the chroma so I get zero interference from anything down stream. I already figured out what was wrong and fixed it.

Are you also lifting the base of Q1? If you don't then you need to add two more resistors to your audio circuit. Otherwise the balance between TIA audio and External audio will be messed up.

Mitch

[Longhorn Engineer]

Mitch, on Sun Dec 13, 2009 4:31 PM, said:

Longhorn Engineer, on Sun Dec 13, 2009 12:59 AM, said:

I lift the MARIA and TIA pin off the board that feeds the chroma so I get zero interference from anything down stream. I already figured out what was wrong and fixed it.

Are you also lifting the base of Q1? If you don't then you need to add two more resistors to your audio circuit. Otherwise the balance between TIA audio and External audio will be messed up.

Mitch

Really? I never noticed...hmm I wonder if there is a way to do Stereo (lift pins 12/13 on TIA) and somehow mix the external audio into both channels?

[thebiggw]

Longhorn Engineer, on Sun Dec 13, 2009 11:16 AM, said:

thebiggw, on Sun Dec 13, 2009 11:10 AM, said:

Longhorn Engineer, on Sat Dec 12, 2009 11:40 PM, said:

Atari 7800 mod V2.1 image

If anyone wants to attempt to make a breadboard version of this mod please do. Unlike the 2600 mod this mod which wasn't to bad to make a breadboard version this mod has two extra SMD chips to deal with. Technically you can leave out the OR chip and the Chroma switcher if you want to do just the 7800 side. I would like atleast one other person make this mod and report that it works before I go off and order PCBS.

Ill post the schematic file tomorrow. After my finals (have one on Monday and Tuesday) I will whip up the PCB layout and then order 100 boards.

I am on vacation starting the 24th, if you post a parts list and where to get the signals from I'll be glad to get the parts ordered and test it out.

-Grant

I would have ordered the PCBs by then but I will post the parts list sometime this week. All the signals are labeled on the schematic. (U3 - 1) = (Chip U3 on the 7800 - Pin 1)

Ok well count me in for a kit soon as they are available then. Thanks for all your hard work!!

[Longhorn Engineer]

Ok I got an email from pcbcart (people I get my pcbs made). The new shipment of PCBs will be delivered on the 22nd. So I will not be able to get any more 2600 mods out before Christmas.

[Mitch]

Longhorn Engineer, on Sun Dec 13, 2009 7:18 PM, said:

Mitch, on Sun Dec 13, 2009 4:31 PM, said:

Longhorn Engineer, on Sun Dec 13, 2009 12:59 AM, said:

I lift the MARIA and TIA pin off the board that feeds the chroma so I get zero interference from anything down stream. I already figured out what was wrong and fixed it.

Are you also lifting the base of Q1? If you don't then you need to add two more resistors to your audio circuit. Otherwise the balance between TIA audio and External audio will be messed up.

Mitch

Really? I never noticed...hmm I wonder if there is a way to do Stereo (lift pins 12/13 on TIA) and somehow mix the external audio into both channels?

Well, there are only three games that use the external audio signal. Ballblazer, Commando and the homebrew Beef Drop. Ballblazer doesn't use the TIA audio at all so it wouldn't be as noticeable.

Also check the audio section of this mod.

I don't know how easy it would be to split the external audio signal since it is only mono.

Mitch

[Longhorn Engineer]

Mitch, on Sun Dec 13, 2009 10:23 PM, said:

Longhorn Engineer, on Sun Dec 13, 2009 7:18 PM, said:

Mitch, on Sun Dec 13, 2009 4:31 PM, said:

Longhorn Engineer, on Sun Dec 13, 2009 12:59 AM, said:

I lift the MARIA and TIA pin off the board that feeds the chroma so I get zero interference from anything down stream. I already figured out what was wrong and fixed it.

Are you also lifting the base of Q1? If you don't then you need to add two more resistors to your audio circuit. Otherwise the balance between TIA audio and External audio will be messed up.

Mitch

Really? I never noticed...hmm I wonder if there is a way to do Stereo (lift pins 12/13 on TIA) and somehow mix the external audio into both channels?

Well, there are only three games that use the external audio signal. Ballblazer, Commando and the homebrew Beef Drop. Ballblazer doesn't use the TIA audio at all so it wouldn't be as noticeable.

Also check the audio section of this mod.

I don't know how easy it would be to split the external audio signal since it is only mono.

Mitch

Well I want to mix the EXT audio into both L & R. I think I got it tho.

[Longhorn Engineer]

And they keep on rolling. Print this guy up and cut it out for the actual size of the mod. The 74HCT OR chip that is on the 7800 is where U4 is on the board. U4 is basically just a header in the shape of a DIP. Remove the 74HCT on the 7800, solder in a socket and pop the mod in. Takes care of all but 5 signals which are picked up at various points across the 7800 board.

 board_outline.pdf   54.44K   51 downloads

Oh and the 7800 mod is mono. Can't do stereo with the External signal without adding another chip and I kinda don't want to add more chips to it already.

Edited by Longhorn Engineer, Thu Dec 17, 2009 12:59 PM.

[Longhorn Engineer]

The new batch of 2600 A/V PCBs where just shipped from China. Should have them on the 22nd.

Also working on the PAL 7800. Going to see if I can get the NTSC and PAL 7800 on the same board. Hopefully with no changes.

Edited by Longhorn Engineer, Fri Dec 18, 2009 8:58 PM.

[Longhorn Engineer]

PAL and NTSC 7800's use a completely different pin out on the OR chip so different PCBs must be made...bummer.

Anyways. I am opening up Preorders for the 7800 mod. It will work just like last time. I will take roughly 15 Assembled and 15 Unassembled orders. After I get all these orders I will put in a order for the PCBs and parts. Once I get them I will ship them out to everyone that ordered. I set up my video mod page here to do the 7800 mods. If it says its sold out then well the 15 of that item is sold out. This is for NTSC 7800's only.

Prices are as follows for the 7800 mod.
Assembled - $45
Unassembled - $30
PCBs - $4
Schematic - FREE!

Preorders take awhile to get out as I have to wait almost 3 weeks to get the PCBs in so please take that into consideration before you order.

[Longhorn Engineer]

I got all Video mod orders shipped today through December 16. When I get back from my trip next week 7800 mods will be shipping out.

[Longhorn Engineer]

Them some nice looking PCBs I reckin.



Just missing the wires and the OR chip. I made a mistake and ordered the wrong ones. Mouser will give me the correct ones tomorrow.

Edited by Longhorn Engineer, Thu Dec 31, 2009 6:55 PM.

[SpiceWare]

reviewed at Retro Thing

[nathanallan]

There are 18 pages in this thread, so I'll ask the question here:

Can I use this inside a 2600 Jr.? Mine has a very bad picture through RF when it does have one. Or is there an easier way? I'm game to try anything, it's been sitting for six months:(

[thebiggw]

nathanallan, on Mon Jan 4, 2010 10:13 PM, said:

There are 18 pages in this thread, so I'll ask the question here:

Can I use this inside a 2600 Jr.? Mine has a very bad picture through RF when it does have one. Or is there an easier way? I'm game to try anything, it's been sitting for six months:(

I modded my junior with LE's kit......and it works fantastic!!!

In fact I got one more kit on the way so I can mod a 2nd 2600 junior to have as a spare and sell the rest of my larger 2600 consoles to save storage room.

Edited by thebiggw, Tue Jan 5, 2010 5:46 AM.

[Longhorn Engineer]

Ok 7800 mods are going to start shipping out soon. Thanks for all those that preordered to get the mod off the ground! You can now just order them through the website on the video mod page like the 2600 mods.

Again big thanks!

I will have the 7800 installation how to and assembly of the mod up in a couple days with comparison shots of RF compared to the S-video and composite output of the mod on both CRT and LCD Tvs.

[Ransom]

Looking forward to it! The wait hasn't been a problem for me. That's because once I get the mod, I'll have to find time to actually install it.

[Longhorn Engineer]

http://www.longhorne...mods/7800ukit21
http://www.longhorne...eomods/7800NTSC

Install and assembly guides for the 7800 NTSC mods V2.1.

[Longhorn Engineer]

By the way this is what the mod for the 7800 used to look like.



Now its this.

[Ransom]

Thank you for the nice instructions!