7800 Restoration

[+-^CrossBow^-]

I would have put a heatsink onto the 6502 as well while you were at it. I ended up putting sinks onto all four of the larger ICs in my daily driver. Now that TIAs are starting to show some issues in relation to heat (More than just color shifting), I figured it was a good & cheap preventive measure.

 

[juansolo]

Mainly we're just doing it to limit the colour drift, it's pretty cool in the UK and the other chips don't get concerningly hot.

 

The other bits arrived also to finish number 3 (@Muddyfunster's machine). The only differences here are that it's got both Composite and S-Video out. The board mounted phono is actually just acting as a frame for a 3.5mm stereo jack running Composite and audio out. Really pleased with the jack situation on this one as it's fully removable and solid without any extra screws or anyhing.

 

Edited September 22, 2021 by juansolo

[marauder666]

Video quality looking good on this one.

 

[+-^CrossBow^-]

4 hours ago, juansolo said:

Mainly we're just doing it to limit the colour drift, it's pretty cool in the UK and the other chips don't get concerningly hot.

 

The other bits arrived also to finish number 3 (@Muddyfunster's machine). The only differences here are that it's got both Composite and S-Video out. The board mounted phono is actually just acting as a frame for a 3.5mm stereo jack running Composite and audio out. Really pleased with the jack situation on this one as it's fully removable and solid without any extra screws or anyhing.

 

Interesting... was the Rockwell CPU purposely wanted in the case of this one? This is the one going to Muddy for having an NTSC machine to test with yes? 

[juansolo]

1 hour ago, -^CrossBow^- said:

Interesting... was the Rockwell CPU purposely wanted in the case of this one? This is the one going to Muddy for having an NTSC machine to test with yes? 

Not intentionally, but it is going to Muddy.

[+-^CrossBow^-]

Hmm... then it could be to his benefit in regards to having it for testing E.X.O.

 

 

[juansolo]

Was having a chat with @-^CrossBow^- regarding the variability of 4050's used in the Chroma Shift circuit so came up with this which allows you to choose the number of gates used with a jumper:

 

 

 

Now with a Toshiba TC4050 with around 55ns propergation time per gate, 5-6 gates is probably about what you're after. For my machine it looks best using all six gates. But the above board is useful for experimenting.

 

However, it gave me an idea based on subwoofer's coarse and fine gain controls. Why not run a 4050 with a really slow propergation time, along with a second that is really fast. Therefore theoretically making possible to dial it in even more accurately. Well this came out of that.

 

 

Now perfboard is my kryptonite. I've done it once beofre maybe 10 years ago and it did not go well. I much prefer veroboard for prototyping which I find much easier to deal with. However this particular circuit just isn't suited to vero sadly. So yeah, not so pretty... But on the upside, it works!

 

 

Until the RGB mods finally surface, this is as close as I can get to one in terms of PQ. It's actually rather lovely. It's using a borderline broken RCA4050BE it runs so incredibly slowly. The other is an insanely quick Ti SN74HC4050. Far too quick for this application on it's own.

 

Edited November 17, 2021 by juansolo

[+-^CrossBow^-]

I think the game to use for really getting this timed right, is Tower Toppler.

 

If you didn't know already, Tower Toppler relies on artifacting to produce the colors of nearly everything in the game minus the timer and score and the bonus screens. But the tower screens and the sprites all rely on it. This is basically how the first tower should took colorwise:

 

 

However, with a UAV by itself on a factory color adjusted 7800, the best you can get that doesn't effect other games is something like this on Tower Toppler:

 

 

The main frog dude color is correct and the timer/score displays are basically correct. But the water and the tower itself along with the enemy sprites are not even close to the right colors.

 

Unlike the above example, the current single 4050 Ti4050BDE chips I'm using going through 3 of the gates can get us to this on Tower Toppler:

 

 

Still not 100% but a bit site better than previous. Also you have to keep in mind that you only see these colors on this game when using RF or composite. S-video due to the more clean signal, does not show the artifacting at all and so the game will look like a striped mess in s-video and better. It is really the only game that suffers when improving the video output form the consoles. Jinxs uses this as well but it doesn't look quite as changed as Tower Toppler does.

 

So yeah, try and see if you can use TT as the basis for dialing in the color because the more they come into sync, the more accurate the artificating becomes it would seem. 

[+DrVenkman]

UNPOPULAR OPINION:

Tower Toppler is a truly shitty game and not worth being the standard to which anyone should want to optimize a console. 

That said, I’d still like to put one of Jesse’s standalone chroma-shift boards into my daily-driver 7800 just because I haven’t had an excuse to open it up in awhile. And while I’m at it, I’d really like to get one of the modified BIOS chips to install as well, if Al ever gets them into the Store.  

[Lostdragon]

1 minute ago, DrVenkman said:

UNPOPULAR OPINION:

Tower Toppler is a truly shitty game and not worth being the standard to which anyone should want to optimize a console. 

That said, I’d still like to put one of Jesse’s standalone chroma-shift boards into my daily-driver 7800 just because I haven’t had an excuse to open it up in awhile. And while I’m at it, I’d really like to get one of the modified BIOS chips to install as well, if Al ever gets them into the Store.  

It really is a poor game and not just on the 7800.

 

 

Had it on the C64 and ST and it's some very clever coding routines, but an absolute frustration fest to actually play. 

[+Muddyfunster]

I've always known that game on other platforms as "Nebulus" never really liked it.

 

[marauder666]

Played it over 30 years ago as Nebulus on ST, looked pretty, plays terrible.

 

[+-^CrossBow^-]

18 minutes ago, DrVenkman said:

UNPOPULAR OPINION:

Tower Toppler is a truly shitty game and not worth being the standard to which anyone should want to optimize a console. 

That said, I’d still like to put one of Jesse’s standalone chroma-shift boards into my daily-driver 7800 just because I haven’t had an excuse to open it up in awhile. And while I’m at it, I’d really like to get one of the modified BIOS chips to install as well, if Al ever gets them into the Store.  

First it needs to be known that all the credit for this chroma fix circuit is due to @marauder666 and @juansolo for even looking into this in the first place. All I did was create a PCB so I could easily add it into 7800 UAV installs going forward. Also keep in mind the current versions of the boards I've got on hand and the new SMD versions I'm waiting to receive are single 4050 chip based and do not allow for selecting different timings. Basically just using a default of about 150ns thereabouts to delay the color signal a bit and bring it more inline to the other signals. But I would guess that for the majority of folks out there, that is really enough since it still looks overall better than it has in the past without something better like RGB output.

 

As for TT, well I don't play the game, but I do think graphically it is pretty impressive and it does the rotation effect very well. I honestly never even knew about the color issues with Tower Toppler until one of my clients reached out to me to ask if there was something wrong with his 7800. That was maybe 2 years ago? Anyway, I confirmed it with my own and warn all my clients since that tower toppler will looks all kinds of wrong with a UAV and there really isn't anyway around that for the time being. The chroma fix circuit comes the closest with a UAV but still not 100% as I've shown above.

 

[juansolo]

Tower Topper / Nebulus has two features that alone would not be a problem, but together elevate the game to a level of bullshittery that is uncalled for. One is the countdown timer, the other is that random bastard that comes along every now again and knocks you off the platform. With just one of these features it'd probably be an ok game. With both, it's is a blend of purest evil and should be purged with fire.

 

I've only ever seen it look right on a NTSC console via Composite and bizarrely only with our mod running as composite rather than S-Video. It looked perfect because, as you say, it relies on composite NTSC artifacting to get it's colours. However the PAL version doesn't have any of that nonsense so out of the box it's just correct with no farting about.

 

Setup today we did with Frenzy (running Berzerk mazes as it's really easy to see if it bleeds one side or the other) and the colour bars, for the same reason. Interestingly there is still some bleed, but it's now an equal amount at both sides.

 

 

I'll go get a grab of Tower Toppler but I guarentee it'll be wrong colour-wise. I tend to find that if the Commando front screen is right, and Ballblazer, everything else is usually ok. (the yellow is a bit blown out in the photo here, but it's fine in person).

 

 

 

Finally a few others while I was at it.

 

 

 

[+DrVenkman]

Let me clarify my earlier comments - 

In no way did I mean to take away from the fundamentally cool work done by @juansolo and @marauder666 in figuring out the color-delay/shift method to improve things. Or the effort needed and undertaken by @-^CrossBow^- to make customers happy if/when they bitch about Tower Toppler after getting a UAV-modded console back. It’s just a damned shame that such a crappy game is basically the measuring stick insisted on by some folks for the overall output of the console. 

 

And again, I would still like to wire one of the Jesse’s boards up inside my 7800 sometime and see the results for myself on my own CRTs, just for grins. 

[juansolo]

The two biggest culprits I notice it on are Dungeon Stalker and Frenzy. It's like a ghost line down the right hand side of the maze on Berzerk and the blues all look a bit wrong on Dungeon Stalker. The ZPH 7800 is particularly bad for it, very similar to my own machine and I can see it all the time. If you've got that going on the shift will likely help. @marauder666 and I are just a little obsessive about such things and our machines are set up in such a way to allow us to bugger about with them to the nth degree in search of picture perfection. It's probably a little excessive to be fair and not really neccessary.

 

I'll go take some more pics in a mo.

[juansolo]

 

 

 

 

 

 

 

Now I haven't adjusted the trimmer on the UAV for this so it's as wrong as ever and I don't care

 

 

For comparison, here it is on PAL where composite artifacting isn't really a thing.

 

 

Tis squished. Really need to set up that PVM for unsquishage...

Edited November 17, 2021 by juansolo

[+-^CrossBow^-]

30 minutes ago, juansolo said:

Now I haven't adjusted the trimmer on the UAV for this so it's as wrong as ever and I don't care

 

 

For comparison, here it is on PAL where composite artifacting isn't really a thing.

 

 

Tis squished. Really need to set up that PVM for unsquishage...

This is pretty much what TT looks like through s-video on NTSC sets which, is also how it looks in emulation most of the time. It looks sharp but you lose all of the color that they hid in there with the artifacting. So each tower ends up looking the same colorwise and the enemies end up not looking correct either.

 

[+-^CrossBow^-]

The SMD version of the C-Fix boards came in today. VERY tiny! but because of that you could install it anywhere. The timings on these 4050s is different so it actually requires turning the UAV trimmer clockwise almost to it furthest point compared to turning nearly all the way to the lowest point on the through hole versions. So it appears to invert the colors even more than before. But I think it allows for even better adjustment now.

 

 

[thomas3120]

On 7/17/2021 at 7:08 AM, juansolo said:

Don't mean to go on a tangent, what is that blue pcb w/jumpers and wires going toward right side of the case.  Scart connector?

And lastly the small pcb with what looks like a relay on it on the left side of the mainboard? (right behind the UAV)

Edited January 4, 2022 by thomas3120

[+-^CrossBow^-]

1 hour ago, thomas3120 said:

Don't mean to go on a tangent, what is that blue pcb w/jumpers and wires going toward right side of the case.  Scart connector?

And lastly the small pcb with what looks like a relay on it on the left side of the mainboard? (right behind the UAV)

@juansolo can answer better than I, but the blue board your see is actually his AVox+ wired directly into the console and the audio out from it wired directly into the system. The 'Scart' connector isn't a SCART connector at all but a switch to allow him to toggle the AVox+ on/off as needed to play 2 player games.

 

The board with the relay on it, is in fact their replacement clock circuit and physical TIA/MARIA color burst cut off circuit. While I've not really seen it on the UAV on NTSC consoles, apparently there is still some interference from the TIA's color burst (or rather... colour burst) signal that affects 7800 games. The relay completely cuts the two apart from each other if I understand correctly.

 

The older LHE s-video upgrade had such an issue with bleeding over of the TIA color burst that actual solder points exist on the LHE so you can wire in a physical switch to turn the TIA color signal on/off as needed. But again, I've not noticed this myself with a UAV on NTSC consoles.

 

[juansolo]

Yup, it's an Atarivox deboxed with it's ports removed. The thing on the right is a switch brings it in and out, but it also puts a bodge on the paddle lines of J2 to get around a bug in that console's TIA that causes problems with Rikki and Vikki. Essentially when playing one player with the Atarivox on the bodge needs to be in place, when playing two player without, it has to be switched out along with it. It was a simple solution that saved me having to source a new TIA and essentially made the problem go away. Audio out from the Atarivox is currently mixed with the Cart+TIA so it's all going out the same jack. I'd normally fit an internal speaker, but this machine gets a lot of fettling, so it was easier to integrate it.

 

We don't fit the separate colourburst clock to the NTSC machine as the way it does the clock doesn't cause the interference that the PAL one does. It does however have the relay on the colour lines to properly seperate them. Which, as you say, is like the LHE mod did. Though it's nowhere near the issue it is on a PAL console so it's not really required with a UAV, it just ensures the purest signal possible.

 

The final PCB is the chroma shift. This machine actually now has a sillier version of it with both a fast 4050 and a slow one on it. Then two sets of jumpers that allow me to go from 0 gates to 12 and any combination between. The reason being to get the chroma shift as close to perfect as I can on my machine. It was an experiment mainly, but it is so nailed on that it ended up staying.

 

The final mods this machine has ares the PAL/NTSC Asteroids BIOS, for no other reason than I could, and a heatsink on the Maria to limit the heat related colour drift you get on the NTSC consoles.

 

At some point I need to dremel out the cup a little also as it can be a bit tight on some carts. I'll get around to that at some point.

 

 

 

FWIW, I'm watching this one as a possible next project: https://www.ebay.co.uk/itm/203778969190?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649 The case is trashed, both top and bottom have significant damage. The pause and select buttons look a little too recessed also... Through the gaps there's signs of significant corrosion. Pretty certain there's no point in saving that case, so might be fun candidate for @PacManPlus 3D printed case maybe? I'll give it a punt if no one bids on it anyhow. It'll still end up £50 by the time it lands here, but that's still cheap for an NTSC 7800 in the UK, and I like lost causes.

Edited January 4, 2022 by juansolo

[+-^CrossBow^-]

5 hours ago, juansolo said:

FWIW, I'm watching this one as a possible next project: https://www.ebay.co.uk/itm/203778969190?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649 The case is trashed, both top and bottom have significant damage. The pause and select buttons look a little too recessed also... Through the gaps there's signs of significant corrosion. Pretty certain there's no point in saving that case, so might be fun candidate for @PacManPlus 3D printed case maybe? I'll give it a punt if no one bids on it anyhow. It'll still end up £50 by the time it lands here, but that's still cheap for an NTSC 7800 in the UK, and I like lost causes.

You are right, the pause, select and I'm pretty sure the Reset buttons all look to be recessed a bit too much. The ONLY think I can think of to cause that is either really worn out, or missing springs under those buttons. Nothing an old BIC pen can't take care of or several as the springs I believe are nearly the same.

 

I wonder what the current status of Bob's 3D printed case replacement is now? I know quite a few of us punted ideas at him on some design changes and maybe it was a bit overwhelming...

 

 

[juansolo]

I think he shelved it. Which is a shame as I thing the other option is the @CyranoJ Tuppaware option ;).

 

The case might be salvagable to be fair, though it'd be a lot of work. Maybe get some sort of mesh in there, fill and sand to shape. Then paint it. It's doable but a lot of work. Dunno if I CBA to do that. Someone else mentioned the cigar box solution, again totally doable. Dunno. Get it working first as the damage and corrosion mean that it could be a bit of a basketcase, but we've done worse. If all else fails, whatever works on there becomes spares and we have a complete lack of NTSC spares.

 

Gotta win it first though, and I suspect someone in the States would just pick it up for spares it being so cheap, whereas I can't really bid much more than it's up for before it becomes too expensive in the state it's in.

Edited January 4, 2022 by juansolo

[+-^CrossBow^-]

9 hours ago, juansolo said:

Gotta win it first though, and I suspect someone in the States would just pick it up for spares it being so cheap, whereas I can't really bid much more than it's up for before it becomes too expensive in the state it's in.

Now the Best Electronics charges more for the the TIA chips than Pokey's it wouldn't surprise me and I've been known to buy a junker or 3 so I have spare parts.