Atari A/V mod update

[Longhorn Engineer]

Quick question, since it's no longer RF, do I put the shielding back on as I reassemble or scrap it?

 

You don't have to.

[yell0w_lantern]

Quick question, since it's no longer RF, do I put the shielding back on as I reassemble or scrap it?

 

You don't have to.

Great! Thanks, Parker!

[horseboy]

Bump for Parker. Buy his stuff.

[yell0w_lantern]

Bump for Parker. Buy his stuff.

 

 

Finished. A/V out work great. Still have to check S-video

[MitchSchaft]

I bought his stuff and can't wait to get it!

[Longhorn Engineer]

By the way I just started a Twitter account if anyone is into that kind of stuff.

[+batari]

Here is my SMT version of the LE mod. Going to install in my Jr.

 

By the way, these are not for sale. Buy his through-hole mod.

[MitchSchaft]

What through-hole mod?

[Longhorn Engineer]

What through-hole mod?

 

my Mods use mostly through-hole parts. One part on the 2600 and two parts on the 7800 are SMD.

[MitchSchaft]

I thought he meant through the hole at the bottom of the 2600 .

[A.J. Franzman]

By the way, these are not for sale.

Darn!

[saundby]

Howdy!

 

LE, I was looking at your history page on your video mod and saw your notes about fighting gate delays on LUMA vs. CHROMA. With the 4050 mod I'm familiar with, there are spare gates on the 4050. Have you considered just putting CHROMA through a spare gate to give it the same delay as LUMA?

 

If this has already been discussed, just point me there. I admit I didn't read all 25 pages of the thread.

[Longhorn Engineer]

Howdy!

 

LE, I was looking at your history page on your video mod and saw your notes about fighting gate delays on LUMA vs. CHROMA. With the 4050 mod I'm familiar with, there are spare gates on the 4050. Have you considered just putting CHROMA through a spare gate to give it the same delay as LUMA?

 

If this has already been discussed, just point me there. I admit I didn't read all 25 pages of the thread.

 

Chroma is received as an Analog signal from the TIA chip so it would not "pass through" the buffer chip.

 

Parker

[+batari]

My SMT version of your board works great - thanks for the schematic. The only thing I messed up is the silkscreen for the output - I got the composite and luma text mixed up.

 

I have a question - the mod does stereo output, but my Commodore 1084 is mono only. Is there a way to also install a mono output jack, while preserving left/right stereo channels? I'd be fine if there is some cross-talk between channels, as long as it's minimal.

[+remowilliams]

Bump for Parker. Buy his stuff.

 

Seconded, the LE 7800 mod I picked up is by far the best out of the many DIY and others that I've used.

[Longhorn Engineer]

My SMT version of your board works great - thanks for the schematic. The only thing I messed up is the silkscreen for the output - I got the composite and luma text mixed up.

 

I have a question - the mod does stereo output, but my Commodore 1084 is mono only. Is there a way to also install a mono output jack, while preserving left/right stereo channels? I'd be fine if there is some cross-talk between channels, as long as it's minimal.

 

you can try adding some 1k resisters in series then joining the two signals.

[Longhorn Engineer]

Bump for Parker. Buy his stuff.

 

Seconded, the LE 7800 mod I picked up is by far the best out of the many DIY and others that I've used.

 

Thanks Remo

[saundby]

Howdy!

 

LE, I was looking at your history page on your video mod and saw your notes about fighting gate delays on LUMA vs. CHROMA. With the 4050 mod I'm familiar with, there are spare gates on the 4050. Have you considered just putting CHROMA through a spare gate to give it the same delay as LUMA?

 

If this has already been discussed, just point me there. I admit I didn't read all 25 pages of the thread.

 

Chroma is received as an Analog signal from the TIA chip so it would not "pass through" the buffer chip.

 

Parker

 

Gotcha.

 

I tend not to think of Luma as digital, though of course here it is since it's just two level. I was scratching my head over that. I thought maybe there was something going on along the lines of CMOS magic, though I didn't see it. Now I see it's just a two level signal.

 

I guess then the question would be, why not use analog amps on both channels (luma, chroma) to maintain the phase relationship? Luma has no real need for a digital buffer. You're just looking to drive a low impedance line, so a pair of low gain amps (a max gain of 2 should make up for any losses) should do the trick without causing timing problems. A reasonably high frequency dual op amp would probably do it. You'd just want to make sure the slew rate is up to par, probably about 250V/uS or better. Anything that can give that good a slew rate will have plenty of bandwidth for old fashioned NTSC or PAL video.

 

Alternatively, a 4016 or 4066 could be used to delay the analog signal if you don't mind adding another component alongside the 4050.

 

Anyway, I'm not trying to tell you how to do it, just suggesting options. There are a number of things to manage in any design, I'm just looking at your phase relationship problem here.

[Longhorn Engineer]

Howdy!

 

LE, I was looking at your history page on your video mod and saw your notes about fighting gate delays on LUMA vs. CHROMA. With the 4050 mod I'm familiar with, there are spare gates on the 4050. Have you considered just putting CHROMA through a spare gate to give it the same delay as LUMA?

 

If this has already been discussed, just point me there. I admit I didn't read all 25 pages of the thread.

 

Chroma is received as an Analog signal from the TIA chip so it would not "pass through" the buffer chip.

 

Parker

 

Gotcha.

 

I tend not to think of Luma as digital, though of course here it is since it's just two level. I was scratching my head over that. I thought maybe there was something going on along the lines of CMOS magic, though I didn't see it. Now I see it's just a two level signal.

 

I guess then the question would be, why not use analog amps on both channels (luma, chroma) to maintain the phase relationship? Luma has no real need for a digital buffer. You're just looking to drive a low impedance line, so a pair of low gain amps (a max gain of 2 should make up for any losses) should do the trick without causing timing problems. A reasonably high frequency dual op amp would probably do it. You'd just want to make sure the slew rate is up to par, probably about 250V/uS or better. Anything that can give that good a slew rate will have plenty of bandwidth for old fashioned NTSC or PAL video.

 

Alternatively, a 4016 or 4066 could be used to delay the analog signal if you don't mind adding another component alongside the 4050.

 

Anyway, I'm not trying to tell you how to do it, just suggesting options. There are a number of things to manage in any design, I'm just looking at your phase relationship problem here.

 

Good idea. I will consider it when I am finishing up the 5200 design.

 

Parker

[A.J. Franzman]

Personally, I think the bigger problem to overcome is that the luma phase to chroma phase relationship in the VCS is not constant -- depending on exactly what hue is being selected, the chroma change will be more or less delayed from the luma change.

[Longhorn Engineer]

Personally, I think the bigger problem to overcome is that the luma phase to chroma phase relationship in the VCS is not constant -- depending on exactly what hue is being selected, the chroma change will be more or less delayed from the luma change.

 

Well if you take the delay away from the buffer and transistor (~20-30ns). Should improve?

[cwilkson]

Personally, I think the bigger problem to overcome is that the luma phase to chroma phase relationship in the VCS is not constant -- depending on exactly what hue is being selected, the chroma change will be more or less delayed from the luma change.

Bingo. It's an inherent problem with NTSC (and PAL too). The reason it looks so terrible on an Atari and not regular TV is that it's exceedingly rare to get perfect vertical edges in a natural picture (TV) vs. a computer generated one. There's really nothing you can do about it. The best you can do is try to center the delays - match the luma edge with color 8 edges. Then the worst chroma delay will only be about 130ns before/after the luma edge if everything else is tuned correctly. But even by doing that, you'll still get into situations where it looks terrible.

 

EDIT: You can also try gaming the luma edge on a per-color basis. But that gets complicated quickly.

Edited September 19, 2010 by cwilkson

[Deteacher]

Well, here's my latest update:

 

On Aug. 18th, LE stated that my mod would be shipped in about a week. On Sept. 7th, I inquired about it, since it hadn't arrived yet. He said it was shipped but if it didn't arrive tomorrow (the 8th) he would ship out another one. On the 8th, I contacted him and told him it did not arrive. He said he would ship another one out the next day (the 9th.)

 

On the 17th, I emailed Parker again and inquired about whether he had shipped a second one out yet. I also asked him to just let me know if he hadn't shipped it. If he hadn't, no big deal. Just tell me so I can stop running home to my mailbox and being disappointed and frustrated on a daily basis.

 

I've been waiting for 3 days for a response to my latest message and I've gotten nothing.

 

I'm still holding onto what everyone else has said...that he'll come through, but it's getting tougher and tougher to do. I have tried to be nice. I feel that I've been more than patient, but this is just becoming ridiculous. I know I could just ask for my money back, but I don't want my money back. I want the product I paid for 4 months ago. I've already prepped my 7800 for the mod, so getting my money back would be counter-productive as I would have $45 and an unplayable 7800. I can't put it back together because the Rf jack is shot (hence the reason I bought the mod in the first place.)

 

I'm at a loss as to what to do from here. I hope that everyone else has gotten what they paid for because this waiting game and constant emails really sucks. What do I do from here?

Edited September 20, 2010 by Deteacher

[Longhorn Engineer]

Well, here's my latest update:

 

On Aug. 18th, LE stated that my mod would be shipped in about a week. On Sept. 7th, I inquired about it, since it hadn't arrived yet. He said it was shipped but if it didn't arrive tomorrow (the 8th) he would ship out another one. On the 8th, I contacted him and told him it did not arrive. He said he would ship another one out the next day (the 9th.)

 

On the 17th, I emailed Parker again and inquired about whether he had shipped a second one out yet. I also asked him to just let me know if he hadn't shipped it. If he hadn't, no big deal. Just tell me so I can stop running home to my mailbox and being disappointed and frustrated on a daily basis.

 

I've been waiting for 3 days for a response to my latest message and I've gotten nothing.

 

I'm still holding onto what everyone else has said...that he'll come through, but it's getting tougher and tougher to do. I have tried to be nice. I feel that I've been more than patient, but this is just becoming ridiculous. I know I could just ask for my money back, but I don't want my money back. I want the product I paid for 4 months ago. I've already prepped my 7800 for the mod, so getting my money back would be counter-productive as I would have $45 and an unplayable 7800. I can't put it back together because the Rf jack is shot (hence the reason I bought the mod in the first place.)

 

I'm at a loss as to what to do from here. I hope that everyone else has gotten what they paid for because this waiting game and constant emails really sucks. What do I do from here?

 

Sorry, I had 1 week to do this lab so I have been stuck on campus for most of the week. I had 1 week to write a simulator for the LC-3 computer. I finished a day early. Getting to emails now.

 

Parker

[Deteacher]

Hey, I completely understand. I'm a college grad (best 6 years of my life) I know you have a lot on your plate, and in the grand scheme of things, a $45 mod board doesn't mean anything compared to getting a good education.

 

It's just been frustrating to not hear anything. If there's going to be a delay, just drop a quick note, or a PM. Folks are going to be a lot more understanding if the lines of communication are kept open.

 

Thanks for looking into it. I really do appreciate it.

 

P.S. My last message to you was a PM, in case you're looking for it.

Edited September 21, 2010 by Deteacher