Heavy sixer: weird score display in Missile Command

[MaximRecoil]

This is my first "heavy sixer"; it just arrived today. Everything seems to work fine, but the numbers in the score in Missile Command are strange compared to my "light sixer" (and compared to it running in the Stella emulator, which looks the same as on my light sixer). On my light sixer, the numbers are always the same medium-weight typeface regardless of the level. On my heavy sixer, the numbers are a bit heavier weight typeface on all of the levels except for the yellow-background level, in which case they are a very lightweight typeface:

Heavy sixer, yellow level:



Light sixer, yellow level:



Heavy sixer, non-yellow level:



I've read that some versions of the TIA do things differently than other versions of the TIA in certain situations. Is this a case of that, or is there something wrong with my heavy sixer?

[MaximRecoil]

I've noticed another anomaly with my heavy sixer. In Combat, in games 1-5 (with the light green background), the player 1 tank (red) barrel turns the same color green as the background when you rotate (when the barrel is facing strictly to the left or to the right is the only time it is red like the rest of the tank). Also, the bullets it fires are always the same color green as the background, making them difficult to see (it is only due to RF artifacts that you can see them at all). The player 2 tank (blue) doesn't have these issues. Its bullets are black/dark, and its barrel doesn't change color as it rotates. None of my other 5 Atari 2600s have these issues.

 

I suspect these things indicate a logic issue somewhere on the motherboard, perhaps in its TIA chip. Does anyone have any ideas? In the meantime, I think I'll swap its TIA chip with one from one of my light sixers to see if that makes a difference.

[MaximRecoil]

Swapping the TIA chip didn't make a difference, and neither did swapping the RIOT chip or the CPU.

 

Also, the issue disappears in B&W mode, for whatever that's worth.

[Osgeld]

Did you fiddle with the hue pot on the motherboard

[MaximRecoil]

Did you fiddle with the hue pot on the motherboard

 

No, because the hue looks right as-is, and I can't see how it could cause completely wrong colors to selectively appear when performing certain actions. Hue adjustments have a global effect, i.e., they don't just affect the barrel of the tank when it is in a certain position or its bullet.

[Osgeld]

Eh maybe I've seen it where the background color won't change but yellow goes green or whatnot just a thought good luck

[MaximRecoil]

Here's a video showing what it's doing:

 

[BigO]

Interesting. The tank treads also lose width when the tank is pointing straight up or down. Losing pixels at the leading and trailing edges of the image as referenced to the scan line. (also losing some in the middle, though)

 

If it were a problem with Player0 or Player1 register, you'd think it would have changed with the TIA swap.

It's possible that the Missile Command score is being rendered with the same Player as the red tank in Combat.

Does this goofy problem only show up for red objects?

 

Just making stuff up: I wonder what would happen with a hacked ROM that made the tank some color other than red? Or made both tanks red.

[MaximRecoil]

Interesting. The tank treads also lose width when the tank is pointing straight up or down. Losing pixels at the leading and trailing edges of the image as referenced to the scan line. (also losing some in the middle, though)

 

If it were a problem with Player0 or Player1 register, you'd think it would have changed with the TIA swap.

It's possible that the Missile Command score is being rendered with the same Player as the red tank in Combat.

Does this goofy problem only show up for red objects?

 

Just making stuff up: I wonder what would happen with a hacked ROM that made the tank some color other than red? Or made both tanks red.

 

No need for a hacked ROM, i.e., in games 6 through 9 and 12 through 14, the background is red and the tanks are green and blue, and there is no issue with either tank on those stages.

 

I think you're onto something with the color red. I didn't make the connection to red objects; I thought it had something to do with the background colors.

Edited October 12, 2015 by MaximRecoil

[MaximRecoil]

Aside from the 3 big socketed ICs which I've already swapped around to no effect, there is only 1 other IC on the board; a small 16-pin IC which a Google search for the number on it (C010816-01) tells me is an Atari IC hex buffer C010816. Could that have anything to do with it? At least 1 of its traces leads directly to the TIA.

Edited October 13, 2015 by MaximRecoil

[7800fan]

That is used to "clean up" the video signal before it's mixed in and fed to RF modulator. An unusual delay could cause it but looking at the schematic, it sharpens 3 luma and 1 color sync, If it was going bad, it would have affected all colors or certain shade would be missing.

 

On some 2600 it is not present at all, the video signal were fed directly to mixer and RF modulator. Some of the AV mod board featured this chip separately from the stock (if present) chip.

[MaximRecoil]

That is used to "clean up" the video signal before it's mixed in and fed to RF modulator. An unusual delay could cause it but looking at the schematic, it sharpens 3 luma and 1 color sync, If it was going bad, it would have affected all colors or certain shade would be missing.

 

On some 2600 it is not present at all, the video signal were fed directly to mixer and RF modulator. Some of the AV mod board featured this chip separately from the stock (if present) chip.

 

It is fixed, and it was that "hex buffer" IC that was the problem. I desoldered it from my heavy sixer's motherboard and also desoldered it from one of my light sixer's motherboard, soldered new dual-wipe sockets into both motherboards, and then plugged the light sixer's hex buffer into the heavy sixer's motherboard. I tested it and it is perfect. Not only does the barrel of the red tank not change color now when rotating, but its bullets are red like they are supposed to be as well. The numbers in the Missile Command score are now displaying correctly as well.

 

I'm curious to see if the problem followed over to the light sixer, which is now sporting the heavy sixer's hex buffer. I have to put everything back together to find out.

[BigO]

That's conceptually way over my head.

I'd be interested in hearing a 2600/TV expert's explanation for how this behavior might me caused by a flaky buffer.

 

Something to do with the buffer maybe not being able to switch at some frequency or other?

Slightly weaker signal from the TIA failing to put a weak buffer over the threshold to change state?

Why just red?

 

Inquiring, less intelligent minds want to know...

Edited October 13, 2015 by BigO

[MaximRecoil]

That's conceptually way over my head.

I'd be interested in hearing a 2600/TV expert's explanation for how this behavior might me caused by a flaky buffer.

 

Something to do with the buffer maybe not being able to switch at some frequency or other?

Slightly weaker signal from the TIA failing to put a weak buffer over the threshold to change state?

Why just red?

 

Inquiring, less intelligent minds want to know...

 

I have no idea either; I just suspected that little IC because my house is the place those little TTL-size ICs come to die, which is why I have several tubes of new 16-pin dual-wipe sockets onhand (whenever I replace one that's directly soldered to the board I always add a socket). I even managed to inadvertently catch one of those little bastards giving up the ghost on video:

 

 

At 8 seconds in it said, "Goodbye cruel world!" I don't know if you've ever worked on an arcade boardset or not, but there are some forty-eleven thousand of those little TTL chips on them. I spent about an hour piggybacking chips and testing until I found the dead one. I've replaced dozens of those things in the 10 years since I got my first arcade machine. I've replaced at least half a dozen of them in my Super Punch-Out boardset alone.

 

By the way, sure enough, the issue followed over to the light sixer. It is now doing exactly the same thing that the heavy sixer was doing before I swapped the hex buffers, both in Combat and in Missile Command. I'll have to order a few of those chips.

Edited October 13, 2015 by MaximRecoil

[BigO]

That's about as conclusive a result as you can get.

 

CD4050 should be pretty cheap. Not sure exactly which flavor(s) will work in the 2600. Probably almost any of them.

Edited October 13, 2015 by BigO

[MaximRecoil]

Does anyone know if this Texas Instruments CD4050BE is a correct replacement? It is the only through-hole CD4050 that Mouser and Digi-Key stocks. Digi-Key also lists two others: another one from TI (CD4050BEE4) and one from Fairchild Semiconductor (CD4050BCN), but they are both non-stock items.

 

Edit: There is also this one (CD74HC4050E), which is the one included in the BAtari Atari 2600 AV Mod Kit. That one's probably a safe bet.

 

And by the way, that faulty buffer did affect colors other than red in some cases, i.e., it affected the Missile Command score numbers regardless of what color they were. As I mentioned in my OP, in most cases the numbers were fatter than normal, especially on the blue background level, where they were so fat that they were all touching each other. Then it went in the opposite direction with the red numbers on the yellow level, where they were all skinnier than normal. Swapping that buffer with a good one brought both the too-fat and the too-skinny numbers back to normal.

Edited October 13, 2015 by MaximRecoil

[Osgeld]

You pribally don't want the 74HC as its cmos in a ttl world... Cmos can be driven from ttl but cmos won't drive ttl which the rest of the circuit on the outputs were designed around given the time

 

It will work in the mod cause from there its going out to video not an rf modulator

 

And I know it didn't work in my jr heh

Edited October 13, 2015 by Osgeld

[MaximRecoil]

You pribally don't want the 74HC as its cmos in a ttl world... Cmos can be driven from ttl but cmos won't drive ttl which the rest of the circuit on the outputs were designed around given the time

 

It will work in the mod cause from there its going out to video not an rf modulator

 

And I know it didn't work in my jr heh

 

What about the CD4050BE? Mouser says that's CMOS as well. Also, what would the 4050 chip be driving anyway? Doesn't it head directly to the RF output? If there are no logic circuits between the 4050 and the video output, wouldn't it be okay to use CMOS instead of TTL?

[Osgeld]

You can try but I dunno whats in the rf modulator and what level of signals it expects and it doesn't have to be a logic device it could be transistors (ttl =transisistor to transistor logic)

Edited October 13, 2015 by Osgeld

[Osgeld]

If you read the first blurb in the data sheet the cd4050 says it will drive dtl and ttl on its outputs

 

Keep in mind I never tried it but out of the two the CD is the one I would bet on

[zylon]

 

What about the CD4050BE? Mouser says that's CMOS as well. Also, what would the 4050 chip be driving anyway? Doesn't it head directly to the RF output? If there are no logic circuits between the 4050 and the video output, wouldn't it be okay to use CMOS instead of TTL?

 

I use CD4050BE's all the time.

[MaximRecoil]

 

I use CD4050BE's all the time.

 

As a replacement for the original (Atari part no. C010816) on a 2600 motherboard?

[BigO]

C010816 is a label that Atari stuck on a standard part.

 

From what I can see of naming conventions in spec sheets, I'd grab the cheapest CD4050xxx that I could find in a DIP package and throw it in there.

If there's one near you, Fry's Electronics probably has one on the shelf.

 

(From what I've seen of ZylonBane's postings and his experience repairing this stuff, yes, he was giving you a context specific answer.)

Edited October 14, 2015 by BigO

[MaximRecoil]

I can confirm that the Texas Instruments CD4050BE is a correct replacement for the original hex buffer chip. I now have a new one in the heavy sixer, the good one I swapped out of the light sixer put back in the light sixer, the bad one in the trash, plus an extra new one for a spare.

[atari-dna]

Does anyone know if this Texas Instruments CD4050BE is a correct replacement? It is the only through-hole CD4050 that Mouser and Digi-Key stocks. Digi-Key also lists two others: another one from TI (CD4050BEE4) and one from Fairchild Semiconductor (CD4050BCN), but they are both non-stock items.

 

 

I've replaced these buffers before, using the 4050BE chip. It's an equivalent replacement.