You usually get reverse polarity in these despite the keyed power connector specifically because that connector is proprietary and people try to hack together their own replacements. The only thing I've seen with a similar connector was a line of Texas Instruments LED calculator from the '70s and none of them had remotely close specs. People make their own power connectors by ejecting female pins from D-sub or KK pin connectors, which are obviously easy to get backwards. It's safest to make your own center-positive DC jack and connect it internally.
I had one of these as a kid. I'm pretty sure I caused that exact same damage due to reverse polarity. I didn't understand what happened at the time, but in retrospect it seems pretty clear. The original power connector is very badly designed. While it is keyed, it's not keyed very well and if you try a little too hard you can end up plugging it in backwards. I was anxiously hooking up my 7800 to play a game I had just received as a present, and as I got the power plug connected, there was a nice pop and plume of smoke coming out of the console, right where that main input cap is located. I wish I still had that console because I believe it was an early revision, but it was thrown out and replaced. That replacement console became a victim of mine about 10yrs ago when I was just starting to get interested in electronics and console mods and such. I still have it, but due to my lacking level of skill at the time it no longer boots properly and will need to be revisited. Got lucky some time after that and came across the most mint 7800 I've ever seen. It even had a socketed 7800 graphics chip, which is quite rare for NTSC consoles (but common for PAL - in your video it's the VLSI chip). It now houses an "XBoard" mod which adds a POKEY and extra RAM using that socket. I'd have never been able to install that otherwise, due to my inability to desolder large chips at the time. I had yet another console for experimentation, but the minty one was thankfully left unmolested. I won't mess with it until I know exactly what I want to do with it, hopefully with much better soldering than what I inflicted on these poor things 10 years ago. It's been a long time, but I recall that composite mod guides sometimes advise that disconnecting the RF will improve the picture, so that might be why that connection was rather brutally broken off.
Thanks again =D You always post really detailed replies here with tonnes of useful information! It is much appreciated and will help anyone reading these messages =D =D As you say, it does sound exactly like what happened to your 7800, and probably countless others if the connector is that bad =/ That XBoard sounds really cool, will have to research those lol.
Was there not an issue with these too that if you plugged the power supply up to mains first and then plugged it into the console you would release the magic smoke or am i comfusing this console with another atari console?
@@tbbw I haven't heard that, but it makes sense that could happen due to the badly keyed connector. You might make contact with the pins before realizing you had it backwards, so it would be a lot safer to plug in the power supply last.
Can you tell me how to get the motherboard out of the bottom case I’ve taken all five screws on the bottom of the Atari 7800 out took off the top but I need to get the motherboard out of the bottom case. How do you do that? thanks for any help.
I've never seen a 7800 before out in the real world. Glad you got it working, that board was pretty messy and looked like some right bodger had a go at the poor thing in the past
I saw one when I was younger but never got chance to play with it. It was a mess and I still don't understand what happened to the capacitor lol. Maybe the PSU went just over the 16v rating on the cap!?! No idea! The solder was the worst I have ever seen - strange so many dry joints etc. Having some trouble with composite mod but I think it's the transistor Ive used. Once the 2N3904 arrives I will upload part 2,
Check your voltages - make sure the VCC / VDD pin on the main chips are getting 5v. If you have power and there's no video, it could be a faulty IC... Or maybe a bad modulator??
re region lockout: I haven't actually tried it, but I think a PAL 7800 will run anything, though there could be some video issues due to differences between the PAL and NTSC graphics chips. Deliberate lockout should only affect NTSC 7800s. The NTSC 7800 boot ROM checks for an Atari signature in the cart ROM at startup. If this check fails then the NTSC 7800 will only allow the game to run in 2600 mode, leaving 7800 resources locked. This allows legacy 2600 games to still work - only 7800 games are restricted. This was Atari's solution to unlicensed carts - software based, rather than hardware based like the NES. PAL 7800 consoles don't use this mechanism, reportedly because the encryption involved wasn't legally exportable. If a game asks a PAL console for 7800 mode then the PAL boot ROM will enable it without any additional checks, so they should happily attempt to run NTSC 7800 carts. The reverse however will not work. NTSC consoles require a signature, and PAL game ROMs do not have them. So PAL 7800 games will not run on an unmodified NTSC 7800 console. Atari had no way to electronically lock out unlicensed 2600 games since the above mechanism didn't exist when those games were coded. However, there is a physical issue that discourages the use of unlicensed 2600 carts. The plastic sleeve that surrounds the cart slot is rather narrow. Atari carts fit fine, but many 3rd party 2600 carts are a very tight fit. They will work, but it's a challenge to get them in. I don't know if this was done deliberately or by accident/lack of caring. A popular solution is to cut a slit in that sleeve which loosens it up. There is some talk on the internet of 2600 software incompatibilites, but they only affect a few games. The 7800's compatibility rate with 2600 games is extremely high. Thankfully, Atari's original ST software for calculating NTSC 7800 game signatures was found by someone many years ago, and the algorithm was worked out. A modern port of that software has been written so signatures can be generated easily today. For a while, homebrew developers were forced to use some ugly tricks to get their games running on unmodded NTSC 7800s.
Thanks, awesome information there =D I didn't know that about the 7800 and licensing protection etc. Cool that someone found the software used for calculating signatures =O
hi there. new subscriber here :) is it possible to do an rgb mod for Atari 7800 ? I know about composite and s video. my unit works great with 7800 games, 2600 games work but there is terrible ghosting. need better than rf for my set up :) keep up the great videos
The video signal outputs from the 7800 and 2600 graphics chips on the board are basically SVideo. There is Sync (don't remember if separate Sync or CSYNC), one pin for Chroma, and a few pins which represent a digital form of Luma. The signals from the Luma pins are at either 5V or ground, making up a digital Luma signal which is converted by a circuit of resistors into an analog Luma. This gets mangled into RF, but given what is available upstream, I think the purest standard video format you can get from a 7800 is SVideo. There are some complications due to the fact that the 7800 contains both a 2600 and 7800 graphics chip, the signals from which have to be mixed. If you dispose of support for both signals, or implement a cleaner way of switching between them, then you might be able to get a more ideal result. I remember seeing reports of a French version of the 7800 that has RGB output, but since the native outputs at the chips are Y/C and not RGB, I am skeptical whether the signal is actually any better than an SVideo mod. I suspect the RGB might have just been kludged in to support what was convenient in that market. Or, maybe there is a SECAM version of the GPU that really has RGB output. If so, that could be interesting.
The colour on the Indy game could be caused by it being an NTSC cart, though I confess to not knowing what the right colours for this game are. The 7800 Asteroids is a great little game, especially with two players. It's a shame the 7800 had such a short life.
I am not sure! I've adjusted the colour since and it does look correct from videos I've seen. It's a very strange game lol! Asteroids looks and plays really well, I can imagine it would be more fun with two players =) It is a shame the 7800 had a short life, it looks like a nice system.
Another one saved from the grave. The console games have aged tho lol. I never owned/played on the Atari as I was on my Amstrad. I remember the 800XL being a good machine. I wouldn't mind picking one of them up a some point along with an MSX
A 7800 version of the Harmony is still pending release. Hopefully we'll get it by mid-year. The only alternative is a Cuttle Cart, which works great, but those haven't been produced for years.
![Chino Pacas - Modo Capone (with Drake & Fuerza Regida) [Video Oficial]](http://i.ytimg.com/vi/zjv8TQ0gBkg/mqdefault.jpg)
Great video as usual, really looking forward to part 2
You usually get reverse polarity in these despite the keyed power connector specifically because that connector is proprietary and people try to hack together their own replacements. The only thing I've seen with a similar connector was a line of Texas Instruments LED calculator from the '70s and none of them had remotely close specs. People make their own power connectors by ejecting female pins from D-sub or KK pin connectors, which are obviously easy to get backwards. It's safest to make your own center-positive DC jack and connect it internally.
Great vid, can't wait for part 2 !
Thanks! Part 2 should be up later in the week!
I had one of these as a kid. I'm pretty sure I caused that exact same damage due to reverse polarity. I didn't understand what happened at the time, but in retrospect it seems pretty clear.
The original power connector is very badly designed. While it is keyed, it's not keyed very well and if you try a little too hard you can end up plugging it in backwards. I was anxiously hooking up my 7800 to play a game I had just received as a present, and as I got the power plug connected, there was a nice pop and plume of smoke coming out of the console, right where that main input cap is located.
I wish I still had that console because I believe it was an early revision, but it was thrown out and replaced.
That replacement console became a victim of mine about 10yrs ago when I was just starting to get interested in electronics and console mods and such. I still have it, but due to my lacking level of skill at the time it no longer boots properly and will need to be revisited.
Got lucky some time after that and came across the most mint 7800 I've ever seen. It even had a socketed 7800 graphics chip, which is quite rare for NTSC consoles (but common for PAL - in your video it's the VLSI chip). It now houses an "XBoard" mod which adds a POKEY and extra RAM using that socket. I'd have never been able to install that otherwise, due to my inability to desolder large chips at the time.
I had yet another console for experimentation, but the minty one was thankfully left unmolested. I won't mess with it until I know exactly what I want to do with it, hopefully with much better soldering than what I inflicted on these poor things 10 years ago.
It's been a long time, but I recall that composite mod guides sometimes advise that disconnecting the RF will improve the picture, so that might be why that connection was rather brutally broken off.
Thanks again =D You always post really detailed replies here with tonnes of useful information! It is much appreciated and will help anyone reading these messages =D =D As you say, it does sound exactly like what happened to your 7800, and probably countless others if the connector is that bad =/ That XBoard sounds really cool, will have to research those lol.
Was there not an issue with these too that if you plugged the power supply up to mains first and then plugged it into the console you would release the magic smoke or am i comfusing this console with another atari console?
@@tbbw I haven't heard that, but it makes sense that could happen due to the badly keyed connector. You might make contact with the pins before realizing you had it backwards, so it would be a lot safer to plug in the power supply last.
Can you tell me how to get the motherboard out of the bottom case I’ve taken all five screws on the bottom of the Atari 7800 out took off the top but I need to get the motherboard out of the bottom case. How do you do that? thanks for any help.
I know this was a long time ago, but I have a 7800 video coming up soon where I hit this same problem lol.
I've never seen a 7800 before out in the real world. Glad you got it working, that board was pretty messy and looked like some right bodger had a go at the poor thing in the past
I saw one when I was younger but never got chance to play with it. It was a mess and I still don't understand what happened to the capacitor lol. Maybe the PSU went just over the 16v rating on the cap!?! No idea! The solder was the worst I have ever seen - strange so many dry joints etc. Having some trouble with composite mod but I think it's the transistor Ive used. Once the 2N3904 arrives I will upload part 2,
OK cool, good luck with the mod
My 7800 just started working in only in B/W. Probably a cap went bad?
It could be that the timing is slightly out and the trim cap needs adjustment, or the crystal related to colour burst frequency has died perhaps.
Hello I have one 7800 but no output video, may you give me some advice to solve this issue please?
Check your voltages - make sure the VCC / VDD pin on the main chips are getting 5v. If you have power and there's no video, it could be a faulty IC... Or maybe a bad modulator??
OMG the Damage to this unit Hurts me! Good luck repairing the board, do check the status of the TIA and the RIOT!
re region lockout:
I haven't actually tried it, but I think a PAL 7800 will run anything, though there could be some video issues due to differences between the PAL and NTSC graphics chips. Deliberate lockout should only affect NTSC 7800s.
The NTSC 7800 boot ROM checks for an Atari signature in the cart ROM at startup. If this check fails then the NTSC 7800 will only allow the game to run in 2600 mode, leaving 7800 resources locked. This allows legacy 2600 games to still work - only 7800 games are restricted. This was Atari's solution to unlicensed carts - software based, rather than hardware based like the NES.
PAL 7800 consoles don't use this mechanism, reportedly because the encryption involved wasn't legally exportable. If a game asks a PAL console for 7800 mode then the PAL boot ROM will enable it without any additional checks, so they should happily attempt to run NTSC 7800 carts.
The reverse however will not work. NTSC consoles require a signature, and PAL game ROMs do not have them. So PAL 7800 games will not run on an unmodified NTSC 7800 console.
Atari had no way to electronically lock out unlicensed 2600 games since the above mechanism didn't exist when those games were coded. However, there is a physical issue that discourages the use of unlicensed 2600 carts. The plastic sleeve that surrounds the cart slot is rather narrow. Atari carts fit fine, but many 3rd party 2600 carts are a very tight fit. They will work, but it's a challenge to get them in. I don't know if this was done deliberately or by accident/lack of caring.
A popular solution is to cut a slit in that sleeve which loosens it up.
There is some talk on the internet of 2600 software incompatibilites, but they only affect a few games. The 7800's compatibility rate with 2600 games is extremely high.
Thankfully, Atari's original ST software for calculating NTSC 7800 game signatures was found by someone many years ago, and the algorithm was worked out. A modern port of that software has been written so signatures can be generated easily today. For a while, homebrew developers were forced to use some ugly tricks to get their games running on unmodded NTSC 7800s.
Thanks, awesome information there =D I didn't know that about the 7800 and licensing protection etc. Cool that someone found the software used for calculating signatures =O
Aaaaw... he cut the ASMR out... what a bastard ;)
hi there. new subscriber here :) is it possible to do an rgb mod for Atari 7800 ? I know about composite and s video. my unit works great with 7800 games, 2600 games work but there is terrible ghosting. need better than rf for my set up :) keep up the great videos
Thanks =D I might do a 7800 RGB video at some point, but before I do that I need to get my 2600 sorted.
The video signal outputs from the 7800 and 2600 graphics chips on the board are basically SVideo. There is Sync (don't remember if separate Sync or CSYNC), one pin for Chroma, and a few pins which represent a digital form of Luma. The signals from the Luma pins are at either 5V or ground, making up a digital Luma signal which is converted by a circuit of resistors into an analog Luma.
This gets mangled into RF, but given what is available upstream, I think the purest standard video format you can get from a 7800 is SVideo.
There are some complications due to the fact that the 7800 contains both a 2600 and 7800 graphics chip, the signals from which have to be mixed. If you dispose of support for both signals, or implement a cleaner way of switching between them, then you might be able to get a more ideal result.
I remember seeing reports of a French version of the 7800 that has RGB output, but since the native outputs at the chips are Y/C and not RGB, I am skeptical whether the signal is actually any better than an SVideo mod. I suspect the RGB might have just been kludged in to support what was convenient in that market.
Or, maybe there is a SECAM version of the GPU that really has RGB output. If so, that could be interesting.
The colour on the Indy game could be caused by it being an NTSC cart, though I confess to not knowing what the right colours for this game are. The 7800 Asteroids is a great little game, especially with two players. It's a shame the 7800 had such a short life.
I am not sure! I've adjusted the colour since and it does look correct from videos I've seen. It's a very strange game lol! Asteroids looks and plays really well, I can imagine it would be more fun with two players =) It is a shame the 7800 had a short life, it looks like a nice system.
Another one saved from the grave. The console games have aged tho lol. I never owned/played on the Atari as I was on my Amstrad. I remember the 800XL being a good machine. I wouldn't mind picking one of them up a some point along with an MSX
Yeah, they have aged! Some great games on the 7800 though, and the Pokey sounds sweet!
Great machine - shame it's region protected. NTSC games and homebrew are much more abundant.
I didn't know that! Is there an Everdrive that works with both 7800 and 2600 games do you know?
GadgetUK164 Not that I know of yet. It does work with a Harmony flashcard I own but only for 2600 games.
A 7800 version of the Harmony is still pending release. Hopefully we'll get it by mid-year. The only alternative is a Cuttle Cart, which works great, but those haven't been produced for years.
Thanks for the info! That's very useful! Hopefully that will be completed! I would love an everdrive or similar for the 7800.