Troubleshooting Diagonal Lines on Video Mod

[PacManPlus]

I actually had the EXACT same issue with my Longhorn mod on my 7800 (diagonal lines). Went back and forth with him a few times, and ended up getting my money back.

[atari2atari]

I actually had the EXACT same issue with my Longhorn mod on my 7800 (diagonal lines). Went back and forth with him a few times, and ended up getting my money back.

 

Thanks for the info!

 

I am VERY optimistic however on a resistor fix on TIA 9 !

 

My early experiments with the resistors I had available, such as a 330 Ohm - - the lowest I had on-hand - - were excellent! I bought a few 100 and 10 Ohm resistors, but the board was no longer working by the time I had those, so I could not confirm.

 

I think the 10 or 100 Ohm resistor on the TIA 9 line right before it enters the video mod board will solve the problem.

 

LittleJoe has offered to help me out and possibly repair my video mod board, if that's the problem, so I am shipping the goods to him this week.

 

 

I will let you all know how it goes, and what the final outcome is!

 

It's a beautiful mod, I do want it to work . . .

 

-a2a

[Deteacher]

I actually had the EXACT same issue with my Longhorn mod on my 7800 (diagonal lines). Went back and forth with him a few times, and ended up getting my money back.

 

Thanks for the info!

 

I am VERY optimistic however on a resistor fix on TIA 9 !

 

My early experiments with the resistors I had available, such as a 330 Ohm - - the lowest I had on-hand - - were excellent! I bought a few 100 and 10 Ohm resistors, but the board was no longer working by the time I had those, so I could not confirm.

 

I think the 10 or 100 Ohm resistor on the TIA 9 line right before it enters the video mod board will solve the problem.

 

LittleJoe has offered to help me out and possibly repair my video mod board, if that's the problem, so I am shipping the goods to him this week.

 

 

I will let you all know how it goes, and what the final outcome is!

 

It's a beautiful mod, I do want it to work . . .

 

-a2a

 

He also offered to fix my mod board. I already sent it off to him. He should be getting it today. Puppetmark is modding my untouched 7800 with the easier composite mod. I can't wait to get both back! Again, it's awesome to have folks who are in the know and can help people like me out. AA Rocks!

Edited March 15, 2012 by Deteacher

[+-^CrossBow^-]

Sorry to resurrect this thread but the outcomes were never listed? I've just installed the longhorn mod board into my 7800 as well and the 2600 video for both composite and s-video is great. But the 7800 composite was giving me these large diagonal lines across the screen with Ballblazer, and when switched to the s-video, I have the diagonal lines and it is black and white? I removed the Tia 9 line and now the composite on the 7800 games looks great, but the s-video still has traces of the diagonal lines. But the s-video does have color with Tia 9 disconnected. But...I also have massive Jailbars on the entire screen? I've only seen this before with cheap s-video cables that combine the composite with the chroma lines but I don't think that is what is happening here.

 

Ideas on how to minimize the jailbars and did adding an extra resistor before the Tia 9 connection on the mod board help?

[Trebor]

Does your install include the updated resistor values shown in the post here?:

 

http://atariage.com/forums/topic/222526-electronicsentimentalities/?do=findComment&comment=2938005

 

Perhaps that will help.

[+-^CrossBow^-]

Appreciate the input Trebor, but this is a version 2.1 longhorn board from Little Joe so it should have all the correct current resistors on it. But you are correct in that the symptom appears to be something in the resistor ladder that the longhorn board in mine is using. I will post some pics when I get home from work so everyone can see what I'm talking about exactly.

[+-^CrossBow^-]

Few more things I wanted to add that I've tried with this now. I did in fact add a trimmer to the Tia 9 line to see if adding some resistance would get rid of the diagonal lines. It does...however, it also removes all color from the 2600 games as well...

 

I've taken some pics of what my mod looks like installed and the results I'm getting with the longhorn 2.1B board I have installed. I received this board from Little Joe about 3 weeks ago but just around to installing it last night. As you can see looking at the attachments, the 2600 side is pretty much good to go. There is some ghosting in the composite side and the s-video has some slight jail bars forming on darker colors like the red of the car in the title screen. In 7800 mode I get black and white with large multicolored diagonal bars rolling diagonally across the screen as can be seen in the Ikari Warriors pics.

 

The first pic is what Ikari Warriors looks like if I cut the Tia 9 line off the mod board. Now the colors are really nice, but the jail bars are a real killer?! I was thinking about taking the Maria 42 and 43 lines off the mod board and running them through the standard genesis svideo amp circuit. I use trimmers on that circuit so I can dial in the right resistance. I figure it should work and I'm curious as what the results would look like? If I did this and it works, then I might just designate the s-video to the 7800 only and the composite to the 2600. Not sure on that yet.

Edited March 26, 2014 by -^Cro§Bow^-

[atari2atari]

Sorry to resurrect this thread but the outcomes were never listed? I've just installed the longhorn mod board into my 7800 as well and the 2600 video for both composite and s-video is great. But the 7800 composite was giving me these large diagonal lines across the screen with Ballblazer, and when switched to the s-video, I have the diagonal lines and it is black and white? I removed the Tia 9 line and now the composite on the 7800 games looks great, but the s-video still has traces of the diagonal lines. But the s-video does have color with Tia 9 disconnected. But...I also have massive Jailbars on the entire screen? I've only seen this before with cheap s-video cables that combine the composite with the chroma lines but I don't think that is what is happening here.

 

Ideas on how to minimize the jailbars and did adding an extra resistor before the Tia 9 connection on the mod board help?

 

Not at all - - I'm glad you resurrected it! I need to play with that system a bit more, I've been distracted with COINOPS 6 !

 

You are correct, and I am remiss - - I never updated on my resolution for the issue. Sorry!

 

I did indeed put the TIA 9 on a hard switch, and simply turned it on it and off when I wanted to go between 2600 and 7800 - -

 

I posted more here: http://atariage.com/forums/topic/197026-mod-log-for-7800-with-best-electronics-euro-os-and-littlejoe-video-mod/

 

But, below is the extract of that:

 

(The TL; DR version - - I just disconnected the TIA 9 and put it on a switch, no resistors added! Color on 7800 is fine when OFF, no bars present, and the 2600 works just fine visually when ON)

 

###

 

I say ALMOST because there was a bit of a video issue that the perfectionist in me wanted to clean up . . . !

 

Add-on Disconnect Switch for TIA 9 on the 2600 Circuit of the 7800 Video Mod

 

Turns out the TIA 9 line causes some interference to the 7800 when it is running in 7800 mode, and the best way to deal with it right now is to just turn off/disconnect the TIA 9 line while you are running in 7800 mode (it was discussed here: http://www.atariage....s-on-video-mod/).

 

The video mod board actually switches "off" the TIA 9 automatically, but the automatic switch is a little "leaky" and the interference still comes through.

 

NOTE - - this interference is the sort of thing that only a video and audio FREAK like me is really going to notice! It's only slightly visible on pure black screens, and I feel you have to be looking for it. This "additional" mod is purely optional, but I like to do things 100%, so I went for it! I think that LittleJoe's video mod is EXCELLENT in it's current form, and this to me isn't a negative in any way! It's just the way it is out here in the wild-west of vintage gaming mods . . . !

 

So, the TIA 9 input is where the blue wire coming off the LOWER LEFT of the board is in this picture - -

 

 

Usually you just wire this point directly to TIA 9, but what you need to do for this mod is put a SPST (single pole, single throw) switch along that line, and flip it to "disconnect" when you are getting your 7800 mode on. Easy!

 

Finding the right switch, however was a bit more challenging.

 

I settled on a classic RADIO SHACK SPST "soft touch" in black and red, which I thought matched the classic stylings of the 7800 - -

 

 

Pop a hole in the case - -

 

 

Wire it up (I used some heat-shrink tubing to cover and clean up my spliced and soldered wires) - -

 

 

I put the switch right under the "lip" of the 7800, where it has easy access, but doesn't visually affect the look of the console at first-glance - -

 

 

Console flipped upside down to you can see how well the plastic matches - -

 

 

And, of course . . . LABELS . . . ! I guess secretly I want to be Captain Picard, as I appear to have used the word "ENGAGE" . . . a subliminal slip?

 

 

 

 

###

[+-^CrossBow^-]

And I just got the damn thing working?! Okay turns out I'm following the pictures too much when I should be looking at others examples and other schematics on this. Since we cut the two resistors ar R5 and R6 I believe? I assumed like an ass that M42 and M43 came off the header points where those two used to be?! yeah.. I just moved R42 over to the leading resistor that is still attached and now I got color across the board and decent video..I say decent because the Diagonals are still present. (Time to put the trimmer back on the TIA9 line). And I have about 4 or 5 thin lines on the far left edge that appear like jail bars in the s-video part of the circuit. Only on the s-video. They are there in composite, but due to the mixing of composite that section is bleeding together.

 

Now that I think about it, I might also be seeing the overscan that isn't normally viewable on a 4:3 SD TV. I'm using an upscaler for all my s-video and composite that outputs back to HDMI at 720P.

 

I'm going to play with the trimmer idea a bit and then depending from that tidy up my new mess of wires and button her up. I'm just glad to finally get something that resembles more like I expected!

[atari2atari]

Hmm, I will admit - - I haven't used the S-VIDEO much, just once, and I wasn't paying much attention!

 

SO, it could be possible I was having issues on that line, but was using the composite and never noticed . . . ?

 

I think you might have a more careful eye, and possibly a better screen!

 

Do post your final results, though, if you would. It will help someone down the line, and I need to get mine back out and tinker with it some, too!

[iesposta]

Leaving the RF box connected may be causing problems.

I installed a Longhorn mod and then moved it from one 7800 to another 7800, restoring the first one and doing a free composite mod with a transistor and 3 resistors. (7800 #1 is a serial #X... which were the last models made, and it will not play some of my homebrew games.)

Both no longer have the RF box, and both have great pictures.

So much better than the original RF.

The Longhorn mod I am using only S-Video, and the original one Composite.

On the Longhorn one I did add the switch which makes the 7800 games nice.

 

Removing the RF box requires a hot solder iron because of the large amount of solder holding the box to the board.

[+-^CrossBow^-]

Okay...got everything in place and put back together. I still have faint jail bars in the overall image on both 2600 and 7800 and S-video. They are present on Composite also but blend in much better. All screen shots of games below were done through the S-video. Notice the left hand side where there is extreme jail bars for about 4 or 5 lines or so that then blend away. All games exhibit this 2600 and 7800 both however, I'm used to this from my s-video Genesis and SMS systems and this is still 100x better then RF so I'm good. At some point I would like to redo the audio and just create separate left and right amps and feed them straight off the TIA outputs, and then combine the pokey Aud-In to each line separately. In fact I did notice that while 2600 games sound great, the 7800 pokey seems more subdued with this mod in place?

 

Anyway, enjoy the pics of my crappy solder skills and screen grabs. I still like the overall look of the mod and do recommend these boards. I believe most of what I'm seeing is just my particular 7800 combined with the AV switcher and upscaler to the TV itself since nearly everything I've s-video modded produces some jbars of some sort within the image. BTW while this 7800 doesn't have the expansion port, it also doesn't contain the circuit for the 2600 Dark Chambers and Activision FE fix either. But it does play Decathlon, Robot Tank, Space Shuttle, and 2600 Dark Chambers carts just fine. And from what I can tell this is still an early production '84 board and so seems to be 100% compatible yeah!

[ApolloBoy]

And from what I can tell this is still an early production '84 board

Actually it looks like your board is from mid-1988 judging by the date codes on the chips. I'm pretty sure Atari didn't implement the extra circuitry until '89 or '90. Edited March 27, 2014 by ApolloBoy

[+-^CrossBow^-]

Actually it looks like your board is from mid-1988 judging by the date codes on the chips. I'm pretty sure Atari didn't implement the extra circuitry until '89 or '90.

 

I didn't mean to imply the system was made in '84 I know that isn't true. I just meant it is using an older '84 production PCB to which all the other components were attached to it. I do actually have a very odd '84 production made 7800 in a box. It was made in '84 according to the chips..expansion port etc on it. But then has small wire jumper patches and resistors on the bottom of the PCB showing it was repaired by Atari. They then stuck the refurbished board into a newer '88 case without the expansion port hole and sold it as new. About 12 years ago I modded it into a dev unit to help Al and the rest of the community dump some of the 7800 games that didn't seem to have complete dumps at the time.