Grand Prix Mystery

[fluxit]

Grand Prix.  A simple, but entertaining racing game by Activision for the Atari 2600.  It boasts convincingly detailed, brightly colored cars, and a sense of speed that seems almost excessive for the amount of track that is visible.  So much as a gentle bump to another car results in one of the most violent displays that can be found in any game.
Without learning the non-random patterns of cars, a few minutes of fun can be had by a single player by determining how much speed is safe before one ends up smacking into the rear of that slower car that you couldn't have seen in time.  Competition between friends for best times can be quite enjoyable as you learn the patterns by heart, and go for that elusive perfect race.

 

 

Where's the mystery?  Well, I'd never actually had a personal copy of Grand Prix back in the day.  I'd only ever played it with friends up until having mislayed one of my favorites by Activision- Megamania, about 10 years ago.  Checking on Ebay, I found that the cheapest deal for an okay quality Megamania was in a listing that included 4 loose Activision carts, including Grand Prix.  After a thorough cleaning, all four cartridges played just fine on my 7800.

 

Moving forward in time to 2 weeks ago, I was missing my original Coleco Gemini from my youth, which I had reduced to components some 20 years past after a modification gone wrong. I found a good looking "for parts or repair" Gemini on Ebay for a nice price, and after a good cleaning and a small amount of adjustment, the Gemini was working well at scratching that nostalgia itch. It played virtually every cart the first time, every time.  That is, until I tried Grand Prix.

 

A pinkish red screen with greyish bars was the result on the Gemini with Grand Prix.  Very occasionally, I'd have a black, rolling screen with grey shaded, moving blips.  I cleaned the cart's contacts again... no change. After several cleanings with still no proper display from Grand Prix on the Gemini, I began to think that perhaps the cart was due for repair, or perhaps the ROM had died in the years since it had last been played successfully.  I switched back to my 7800, and Grand Prix fired right up, and played perfectly.  Reinserting the cart in the 7800, it again started properly with no special care.  Had the cart fixed itself?

 

Switching back to the Gemini, there was still just a pinkish red screen with greyish bars instead of the race track.  No amount of reinsertions(switching off the power, of course) would ever load the game properly.

 

In spite of the fact that *every* other cart I have out of storage at the moment, some 27 carts, including other  Activision carts will load properly, and usually with a single insertion, the Gemini's contacts did have a very gentle grip on the carts, so I decided to remedy that.  Removing the rivets holding the cart guide to the board freed the guide, so that I could easily(gently, and carefully) increase the tension applied by the Gemini's contacts.  I replaced the rivets with low profile hex head M3 screws, loctite, nuts, and fiber washers to protect the PCB.

 

Trying a few of the games that had previously worked on the Gemini showed good results.  They still played fine, and now the console had a positive grip on the cart that offered some resistance when removing them from the slot.

 

The moment of truth had come.  I inserted Grand Prix, and turned the power switch to on.  The result was unchanged.  I was greeted by yet another pinkish red screen with greyish bars.  It couldn't be true.  Was this cart actually incompatible with my Gemini?  A couple of web and Atariage searches turned up no definitive results regarding Gemini game compatibility problems.

I decided to try another Grand Prix cart, as another similar quality cart could be had for $7 shipped.  A week later the filthy new cart arrived, and after a good cleaning, I inserted it into the Gemini and flipped the switch, to be greeted by... a proper Grand Prix game screen.

Switching back to the 7800 with the newly acquired Grand Prix cartridge, there was to be found... a pinkish red screen, with grey bars.  A reinsertion on the 7800 showed the same.  I switched back to the original cart on the 7800, and the game fired right up.

TLDR; the mystery is that I have 2 Grand Prix carts.  For my real consoles, one cart only works on the 7800.  The other cart only works on the Gemini.  Seemingly, no amount of cleaning or reinsertions will ever change this.

 

Both carts work perfectly on my Retron 77, and checked out as having the same ROM on the R77.

[insertclevernamehere]

I have this issue with a fair amount of Activision carts and it only ever seems to be Activision.  Usually you fully insert a cart and away you go but I find that the sweet spot on some Activision carts is closer to the end of the pcb.  I usually fully insert them and then pull them back out ever so slightly or just not fully insert the cart to begin with, turn the 2600 on and the cart works.  Sometimes I have to repeat it a couple of times to get it just right but it does the trick.  

[fluxit]

What I don't understand is the consistency.  I've measured with a caliper.  Both carts are 11mm from the cart edge to the pcb.  1 mm from the pcb edge to the contacts.  Those are the same measurements that I get for Atari, and Spectravision carts as well.  Activision contacts do seem to be of worse quality, however, and do not tend to clean as easily as other carts.  FWIW, I have tried backing the carts off by about a millimeter when inserted, and it seems to either make no difference, or make the problem worse(black screen.)

 

Again, Grand Prix is the *only* cart that does this.

[BigO]

It doesn't explain why Grand Prix and not other Activision games, but I once was told that Activision circuit boards are thinner. At the time, I was inquiring about problems I had with Activision games.

 

I don't recall the numbers now but did confirm via digital caliper that Activision's boards were thinner than others.

 

Maybe both Grand Prix cartridges in question used an especially thin batch of PC board material?

[Lauren Tyler]

The Atari 7800 has also been known to have issues with The Activision Decathlon and Robot Tank.  With the latter, I've always been lucky in that I've had my copy work fine.

[+Nathan Strum]

I've had issues with some Activision carts in my 2600. Pitfall! in particular. The circuit boards just don't make as good of contact as other carts. Not sure how much of this has to do with the thinness of the PCB itself, or just the Activision shell not fitting as snugly as other designs, or the quality of materials used. Activision certainly cheaped-out on their label glue.  

 

Sometimes cleaning the cart's PCB helps, but I've found my system to be much more forgiving towards iffy carts after having cleaned the contacts in the 2600's cartridge slot itself (see the bottom of this post). Some carts still don't behave though, but shimming them with a thin piece of cardboard (between the top of the cart and outer edge of the cart slot) will often wedge problematic games in place enough for them to work.

 

For cleaning the cart contacts, I used contact cleaner or isopropanol (99% if you can find it, although 91% is acceptable - the 70% stuff is 30% water, and isn't suitable for electronics). For really bad oxidation, Flitz may also work. It's a great non-abrasive metal polish, although I'll admit to not having tried it on contacts, as it's a bit of a mess to clean up. I suppose I should try it sometime and see what it does (and how it is to clean out of a cart afterwards).

[BigO]

How do you go about applying the necessary physical agitation/polishing of the contacts down in the slot?

 

I've used card stock, fabric wrapped around credit card plastic, chamois covered swabs, and probably other methods I can't recall to apply tech grade IPA and Deoxit. I have  never ended up feeling comfortable about having actually cleaned the contacts well.

[+Nathan Strum]

I use thin cardboard, soaked in IPA (or the contact cleaner I linked to above). Something a little thinner than a typical cart PCB, and smooth enough so it won't shred and leave debris behind. I just soak it, insert and remove it several times, then trim off the gunky part of the cardboard and repeat until it no longer comes back out dirty.

 

There's someone who actually makes and sells a cart slot cleaner, but I haven't tried it.

[fluxit]

On 11/30/2023 at 9:33 AM, Nathan Strum said:

I've had issues with some Activision carts in my 2600. Pitfall! in particular. The circuit boards just don't make as good of contact as other carts. Not sure how much of this has to do with the thinness of the PCB itself, or just the Activision shell not fitting as snugly as other designs, or the quality of materials used. Activision certainly cheaped-out on their label glue.  

 

Sometimes cleaning the cart's PCB helps, but I've found my system to be much more forgiving towards iffy carts after having cleaned the contacts in the 2600's cartridge slot itself (see the bottom of this post). Some carts still don't behave though, but shimming them with a thin piece of cardboard (between the top of the cart and outer edge of the cart slot) will often wedge problematic games in place enough for them to work.

 

For cleaning the cart contacts, I used contact cleaner or isopropanol (99% if you can find it, although 91% is acceptable - the 70% stuff is 30% water, and isn't suitable for electronics). For really bad oxidation, Flitz may also work. It's a great non-abrasive metal polish, although I'll admit to not having tried it on contacts, as it's a bit of a mess to clean up. I suppose I should try it sometime and see what it does (and how it is to clean out of a cart afterwards).

After sitting unused for a week, the Gemini's verboten Grand Prix cart shows only a black screen(like an empty slot) on the Gemini.  Shimming the offending cart gives me varying color combinations of  vertical stripes, but the game never loads beyond stripes. 

 

Meanwhile, an Ebay Stampede cart that I repaired recently, works every time.  It has a chunk taken out of the cart case, and had a broken alignment peg and screw boss.

[fluxit]

The case of the curious cart continues.

 

Wondering if a third cart from Ebay would land on one side or the other, working on the 7800, or the Gemini, I ordered a Grand Prix with the worst looking label that I could stand.  Here are the three carts.  The original that doesn't work on the Gemini is on the left.  The cart that always works on the Gemini is in the center.  The 'newest' cart on the right, does- after a thorough cleaning, work on both the Gemini and the 7800.  All three always load right up, no replugging required on the Retron 77.

So I decided to eliminate(more or less) the slots of the various devices as a factor, and made an edge connector extender.

Don't mind the extra (2) golden fingers.  They aren't connected.  The board is a cut down floppy drive adapter.

Through the extender, all three carts now work on  my 7800.  This would seem to confirm that my 7800's contacts could use some tightening to improve it's 'Activision board compatibility.'

 

The original cart *still* doesn't work on the Coleco Gemini, though.  I tried it at least 5 times, replugging into the extender, and then into the slot.  The Gemini just displays a black screen with that cart.  The other 2 work fine through the extender on the Gemini, just as they do when plugged directly into the slot.

Edited February 3 by fluxit
added images

[82-T/A]

Grand Prix was one of my all-time favorite games growing up. I don't know why or what prompted my mom to buy it... probably because my dad liked Formula-1 when I was a little kid... but man, I played that game almost more than any other. That game, Pole Position, Battle Zone, Maze Craze, and Solaris were my go-to games...