"Dragonfly" my version of the Atari 7800 SD cartridge

[+-^CrossBow^-]

On 2/14/2021 at 12:28 PM, GoldenWheels said:

I'm having low sound issues with a few roms on an RCA modded (no not sure which mod) model. Anyone else? My 7800 seemed fine before and normal carts sound ok. Maybe I'll try my normal unit.

Depends on how the composite upgrade was done in regards to audio. If your normal games sound okay like commando and ballblazer having the same volume as other games, then the DF cart has some adjustment trimmers on the back of the PCB. You do have to open it of course to get to them. They are marked as PR and PL I believe and if you only have in single pokey mode, then you only need to adjust the top trimmer. The middle trimmer is for dual pokey mode with the pokeyMAX and the bottom trimmer is for adjusting the Yamaha sound.

 

If that doesn't make much of a difference, then the issue is how your audio was likely done on the AV mod work.

 

[rj1307]

Software update.
Changes:
- changing the way files are loaded. Pressing the "Enter" button on the file will display one full name from the header. If we want to load this file into memory we press "Enter" a second time, if we want to change the file we press "Plus" or "Minus".
- removing the "Show Name" option in the Menu 

 

To update the cartridge, upload the dragon.bin file to the root directory of the SD card, insert the SD card and turn on the cartridge's power supply. The bootloader will start automatically, after it is finished, delete the dragon.bin file from the SD card.

 

I haven't tested this version because I'm on a business trip until the end of the week, but everything should work. 

The next tweak will be adding support for new header settings for Yamaha and Dual Pokey, but that's after returning home. 

 

 

v1.05.zip

[+-^CrossBow^-]

This is a very cool update! What I've been doing is on each WIP release, I go into the file with a hexeditor and add in the name of the game and WIP date so that when scrolling between the files on the cart, the internal name will tell me which is which.

 

[Shaggy the Atarian]

Apologies if this was covered already, but I did a search for TIA and looked in the manual and could not find the answer.

 

I got my DragonFly and one of the recommended PSUs per this thread (thanks!). Games load up just fine and games with Pokey sound work (I got the Pokey Max build, no YM yet). But when I try any game with just TIA sound - it's 100% silent. I did mod my 7800 with composite out, but TIA works on normal carts and like I said, Pokey sounds work. I fiddled with settings a little but no luck so far - please help!

 

[rj1307]

What you write is very strange, Dragonfly does not interfere with TIA's audio path in any way and no settings will cause it to be turned off. Can you describe exactly what the console modification was? 

[Shaggy the Atarian]

1 hour ago, rj1307 said:

What you write is very strange, Dragonfly does not interfere with TIA's audio path in any way and no settings will cause it to be turned off. Can you describe exactly what the console modification was? 

Only mod I made to the system was the composite video mod. It's been a while, but pretty sure it was one of these off of eBay. 

 

Never had a problem with TIA audio prior. ?

[rj1307]

What was this modification all about? Have you changed summing resistors for TIA / POKEY? 

[Shaggy the Atarian]

This mod replaced the RF out signal with composite out. As I recall, you have to reroute the video/audio circuit. This video shows what is used:

 

 

Is it possible that I have a resistor somewhere in my 7800 that's bad or failing that could be causing this? 

[+-^CrossBow^-]

39 minutes ago, Shaggy the Atarian said:

Is it possible that I have a resistor somewhere in my 7800 that's bad or failing that could be causing this? 

The TIA audio isn't even attached to anything that the DF cart does. Only the external audio line that provides support for POKEY games. 

 

What 7800 games have you tried on your DF cart that aren't providing TIA sound but the actual carts work? 

 

[rj1307]

Well, something is wrong here, in the video you can see that the R5 resistor is removed, which cuts the Pokey sound from the cartridge, so how come you have the Pokey sound? 

[+-^CrossBow^-]

15 minutes ago, rj1307 said:

Well, something is wrong here, in the video you can see that the R5 resistor is removed, which cuts the Pokey sound from the cartridge, so how come you have the Pokey sound? 

You are correct in this and this is still in the current common composite instructions. But if you watch further in the video, he realizes he doesn't have pokey sound, and connects a wire off of where C10 was removed. That point he solders to is one of the first vias on the external audio line and he is tapping the pokey audio from there and likely ran it to the RCA jacks.

 

 

[Shaggy the Atarian]

3 hours ago, -^CrossBow^- said:

The TIA audio isn't even attached to anything that the DF cart does. Only the external audio line that provides support for POKEY games. 

 

What 7800 games have you tried on your DF cart that aren't providing TIA sound but the actual carts work? 

 

Not sure why it's behaving like this but every single original 7800 game that only uses TIA are completely quiet when played on the DF cart, while Pokey games play their sounds just fine. I've tested several of my regular carts - Xevious, Midnight Mutants, Dark Chambers, Centipede, etc. in their regular cart form where there are no sound problems at all. Never had an issue with TIA in the past, so that's where this was a surprise.

 

Guess I'm the only one experiencing this problem...too bad I don't have a spare 7800 to test on.

Edited February 18, 2021 by Shaggy the Atarian

[rj1307]

After this modification, are the TIA sound and the POKEY sound still summed up by resistors? If so, what are their values? 

Edited February 18, 2021 by rj1307

[Shaggy the Atarian]

Unfortunately I have no idea. When I get home tonight I'll have to see if I can open up my 7800 and figure it out. I did this mod years ago, so don't remember details like that, but I'll let you know. Thanks for the help!

[Yellowman]

Hi,
first of all: Dragonfly is fantastic. I love this little dragonfly.

Unfortunately I also have this TIA sound problem, but only on my NTSC console with converted A / V output.
On my PAL consoles, one with UAV (S-Video), one with simple A / V conversion and one original (HF tuner), 
everything works as it should. No problem.
Only the NTSC console is causing a little trouble. Original modules (NTSC) run perfectly. 
BallBlazer with harmonized Pokey / TIA sound. Or Xevious with only TIA sound. 
But with the Dragonfly, I have no TIA sound on the NTSC console, only Pokey and YM. 

At the weekend I have to examine the conversion again carefully.
It is the simple conversion that is also described somewhere here on AtariAge. 
Apparently the audio circuit is different than with the PAL consoles.

[SoundGammon]

Where can I buy one?

[+-^CrossBow^-]

52 minutes ago, Yellowman said:

Hi,
first of all: Dragonfly is fantastic. I love this little dragonfly.

Unfortunately I also have this TIA sound problem, but only on my NTSC console with converted A / V output.
On my PAL consoles, one with UAV (S-Video), one with simple A / V conversion and one original (HF tuner), 
everything works as it should. No problem.
Only the NTSC console is causing a little trouble. Original modules (NTSC) run perfectly. 
BallBlazer with harmonized Pokey / TIA sound. Or Xevious with only TIA sound. 
But with the Dragonfly, I have no TIA sound on the NTSC console, only Pokey and YM. 

At the weekend I have to examine the conversion again carefully.
It is the simple conversion that is also described somewhere here on AtariAge. 
Apparently the audio circuit is different than with the PAL consoles.

I'm assuming that orange wire with the resistor added in is the TIA audio? Try removing the resistor and soldering that wire to the base of R6 instead directly next to the audio tune coil.

 

[+-^CrossBow^-]

1 hour ago, Shaggy the Atarian said:

TIA are completely quiet when played on the DF cart, while Pokey games play their sounds just fine. I've tested several of my regular carts - Xevious, Midnight Mutants, Dark Chambers, Centipede, etc. in their regular cart form where there are no sound problems at all.

What about Commando? That uses TIA for sound effects and I think the percussion while the Pokey is all the background melody. Based on what you are saying, on the DF card you should only hear the music and no sound effects on Commando?

 

I've not tested every one of the 7800 roms on the DF cart but I have tested commando and confirmed on my 7800 and DF cart that it was all working properly. The ONLY issue I had is that my DF cart pokey audio was way too loud at first and I had to adjust the trimmer pots on the back of the PCB all the way down to bring the pokey and TIA more in balance on volume again. 

 

So my next question on this if if you play ballblazer on the DF cart, were you then having to turn down your volume when you popped in an actual cartridge game like Xevious or Joust...etc? That would at least confirm that you might need to adjust the pokey audio on the DF cart and you don't really hear the TIA because the pokey is set to loud. But that would really only show up on pokey+TIA audio games like Commando.

 

 

[Shaggy the Atarian]

1 minute ago, -^CrossBow^- said:

What about Commando? That uses TIA for sound effects and I think the percussion while the Pokey is all the background melody. Based on what you are saying, on the DF card you should only hear the music and no sound effects on Commando?

 

I've not tested every one of the 7800 roms on the DF cart but I have tested commando and confirmed on my 7800 and DF cart that it was all working properly. The ONLY issue I had is that my DF cart pokey audio was way too loud at first and I had to adjust the trimmer pots on the back of the PCB all the way down to bring the pokey and TIA more in balance on volume again. 

 

So my next question on this if if you play ballblazer on the DF cart, were you then having to turn down your volume when you popped in an actual cartridge game like Xevious or Joust...etc? That would at least confirm that you might need to adjust the pokey audio on the DF cart and you don't really hear the TIA because the pokey is set to loud. But that would really only show up on pokey+TIA audio games like Commando.

 

 

Funny enough Commando was one of the first games I tried on the DF, and that's where I noticed there was an odd issue as I expected to hear shots and explosions but it was just the music. I also tried BB, although I will have to try it again to see what the differences are between volume levels on regular carts and the DF. Thanks!

[+sramirez2008]

On 2/16/2021 at 11:18 AM, rj1307 said:

Software update.
Changes:
- changing the way files are loaded. Pressing the "Enter" button on the file will display one full name from the header. If we want to load this file into memory we press "Enter" a second time, if we want to change the file we press "Plus" or "Minus".

Loving this update. -Thanks?

[+-^CrossBow^-]

BallBlazer is POKEY only so that one won't tell you anything. But you should be able to hear the sound effects on Commando so if you don't that is very odd. On mine they were there but just much lower in volume as compared to the pokey music so that is why I had to adjust the pokey trimmers all the way down on my cart. 

 

I'd be curious what would happen on these composite AV modded consoles if you were to just attach your audio out in a similar fashion as I do on the systems I've upgraded with UAVs? But that requires putting 6k8 back in on R5 and then attaching the audio out from the other end of R5 and R6 tied together with an additional cap off that for additional filtering.

 

[Shaggy the Atarian]

From the sounds of it I may have to try re-modding the mod, although I can't remember what the original instructions are (probably all in on that video). What cap would need to be used between the R5 & R6?

 

[+-^CrossBow^-]

What I do when I upgrade 7800s with a UAV (And I would likely do the same with composite since I know it works), is one of two things:

 

If you want to keep the RF modulator fully working, then I add a 6k8 resistor to the bottom lead of R5 and an 18k resistor from the bottom leg of R6. These are the same values of the originals on NTSC boards. Then the remaining ends of the resistors I twist together and solder as one small lead. I then attach the + lead from a 10µf cap (16v or above), from the twisted resistor ends and run a wire from the negative lead of the cap to my actual RCA jacks. 

 

If you don't care about the RF modulator, or have removed it, then you just have to clip or desolder the legs of the R5 and R6 resistors facing towards the back of the console, twist those leads together and follow up with the 10µf cap again and out to the RCA jacks.

 

 

[+DrVenkman]

4 minutes ago, -^CrossBow^- said:

If you don't care about the RF modulator, or have removed it, then you just have to clip or desolder the legs of the R5 and R6 resistors facing towards the back of the console, twist those leads together and follow up with the 10µf cap again and out to the RCA jacks.

That’s what I did on my own system. ?

[Shaggy the Atarian]

As I recall, the mod had me remove the RF modulator, so pretty sure that's what I did. I'll see if I have a 10uf cap laying around...doesn't matter what the voltage is? Also so I'm understanding correctly - one leg of the cap goes from the twisted leads to the RCA jacks? Does it matter polarity used?