Bad joystick port.

[loggahead]

Hello All,

 

I have a 2600 console that I cannot play through the second joystick port. When a stick is plugged into the second port and the the fire button is pressed, the screen distorts (it looks like it does when you are on the wrong channel). The screen stays distorted until you let go of the fire button. Here is something even wierder, if you are playing a 2 player game (I tried both combat and joust), when the fire button is pressed on the second stick, it acts as if both sticks' buttons were pressed.

 

I tried different sticks and games. I trid cleaning all the connections and no change. The soulder points seem to be in good shape, any other ideas?

 

-logga

[Breakpack]

Do you have a Genesis control pad handy?Check that out and see if you get the same results(Genesis pads work,but only the B button acts as the button)

[loggahead]

Unfortunately I don't

 

I have a Sega Nomad (portable Genesis) but no extra controllers. Any other ideas?

 

-logga

[spongebue]

Sounds like a bad TIA (AKA Stella) chip.

[Kroko]

Why do you think its the TIA ? Couldn't it also be the RIOT ?

[loggahead]

Are you referring to the dip chips on the mainboard? I am not sure if this one is a heavy-sixer because the the serial is gone on the bottom. It is the same make wilth the joystick ports close together on the back of the console at the bottom. I noticed the mainboard that the joystick ports are on has some dip chips on it.

 

I read somwhere that Atariage.com has schematics, is that true? And if so, where can I get replacement chips? Or should I just look for another one on Ebay. Unfortunately, this one is from Ebay.

 

-logga

[vb_master]

Best Electronics - Rescource for Atari 2600 (and others) chips.

I suspect it's the RIOT, and not the TIA because the TIA handles TV Output.

[loggahead]

I have had some issues with TV output, when the second joystick button is pressed, the screen distorts badly and it makes both players fire/jump.

 

On Best Electronics, is a RIOT chip the standard I/O chip? And also, is it just a matter of pulling the chip out of its dip socket and replacing it with the new one?

 

-logga

[loggahead]

but come to think of it . . . .

 

I did seem to think that the sound of the tanks on Combat sounded a little odd. Then again, it could have just been my imagination. As long as you are playing with a joystick on port 1 and only playing single-player, the console seems to work great!

 

-logga

[vb_master]

Don't know.

[Breakpack]

Sounds like a bad TIA (AKA Stella) chip.

 

LOL,nice avitar!

[Blinky]

Why do you think its the TIA ? Couldn't it also be the RIOT ?

 

Maybe. Because the fire buttons are read by the TIA :wink:

 

TIA might be bad. But you might want to try cleaning the circuitboard first and see if that helps. Open up your (6 switch?/4 switch?/2600JR?) Atari and inspect the PCB for dirt or goo or anything that might cause a short. Dirt can be cleaned with an old toothbrush, with sticky dirt or goo you'll need a cleanser too

[Kroko]

Maybe. Because the fire buttons are read by the TIA  

 

Sure, that sounds logical

[loggahead]

I'll check the PCB one more time for goo and such. I will also try reseating the dip chips. I have another 2600 (a 4 switch model). I was thinking of pulling the chips out of it and putting them in the broken 2600 (a 6 switcher) to find which chip is bad. They are cross compatible right?

 

Does anyone have a pic of a 2600 or 2600a PCB that they could point out what chip is what? I noticed there are three on both PCB's of mine. I assume that is the CPU, Stella, and RIOT. I just do not know which is which.

 

Thanks so much for all the help guys!

 

-logga

[Kroko]

The CPU is easy, because it has less pins than the other two :-)

So the smallest of the 3 chips is the CPU.

 

Here are some numbers that might help you:

 

RIOT: CO 10750

TIA: CO 11903

CPU: CO 10745

 

You should be able to find these numbers on the chips in your VCS.

 

Kroko

[Blinky]

The one with the problem is a 6-Switch ?

 

Then probably the small 4050 chip is faulty. The fire buttons go through it , so do the video signals. It's a common chip and still easy and cheap to purchase. Unfortunately it is not socketed and needs to be desoldered. If you can handle a soldering iron and a tin sucker then you can do it your self. otherwise ask someone who can.

 

If you want to try interchanging the RIOT/TIA (bigest) chips anyway:

 

The one closest to the cart slot is the RIOT.

The one in the center is the CPU.

The one on the bottom is the TIA

 

The chips have the same pin assignment and are interchangable. However there could be some minor electical differences (slightly different display). But thats nothing to worry about for your testing.

 

Before removing the chips I recommend to put a small label(can be removed easely afterward) on them or mark them. So you know where to put them afterwards. You could mark them as T6,M6,B6 and T4,M4,B4 (Top/Middle/Bottom/6switch/4switch). Test B6/B4 first.

[loggahead]

Ok, cool. Great info.

 

I don't have the broken 6-switcher here with me, but I am looking at my 4-switcher and I don't see a 4050 chip. I take it that was only on the 6-switchers?

 

Looking at this 4-switcher, I see the C010745 (CPU) and the C010750 (RIOT) and they both have an Atari logo on them, but the Stella chip looks a little newer and has an "S" logo on it. It's number is C010444D. Odd, this is the Atari I have had since a kid and have never had any work done it.

 

BTW, I am having a blast troubleshooting this. I am excited about all of this because my son (who is curently 3 months old) is going to be able to play the same games I played when I was his age. I've liked playing just about every console out there from the 2600 on up, I am even an XBOX fanatic. But one thing is for sure, they just don't make video games like they used to. I played and beat Pitfall II this morning and man was I in heaven. Although my highscore wasn't near what it could have been

 

If anyone is interested, I won a couple of EBAY auctions online to piece together some orignal joysticks and such and am selling the spoils. No one has bid yet and it ends today in case you are interested. It is a 7800, 2600 jr., and a couple of sticks.

 

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...me=STRK:MESE:IT

 

-logga

[Blinky]

4-switcher and I don't see a 4050 chip.  I take it that was only on the 6-switchers?

 

It is used in later models. But not all 4 switches.The joystick fire buttons don't go through the 4050 in most of those later versions too.

 

Looking at this 4-switcher, I see the C010745 (CPU) and the C010750 (RIOT) and they both have an Atari logo on them, but the Stella chip looks a little newer and has an "S" logo on it.  It's number is C010444D.  Odd, this is the Atari I have had since a kid and have never had any work done it.

 

Probaby from a different production run.

[loggahead]

Ok, I tried the RIOT, Stella, and CPU chips from my working 2600A and the 6-switcher still does the same. I also went over the PCB with some rubbing alcohol and a toothbrush and cleaned it thoroughly.

 

Next chip, the 4050?

 

-logga

[Blinky]

Next chip, the 4050?

 

Yes.

 

(read following completely before taking any actions)

 

Some tips on removing it. Make a note of how the 4050 is positioned.

Pin 1 is indicated by a small round dot, a notch in the chip at that side

or its the bottom left pin when you read the chip from left to right.

 

 

To remove the chip just cut all the pins at the top of the pins with a sidecutter and remove the legless chip. Now you can do two things.

 

• Solder the new chip to the old pins (could be a bit tricky).

• heat up each pin and pull the pin gently out. After removing all pins. heat up the holes and suck out the remaining solder with a desoldering tool (solder sucker). This is easier with an extra person holding one of the tools. After all holes are clear. Get out that that tooth brush again to remove any small bits of solder from desoldering. insert a socket into the holes with the notch in the right position, keep a little pressure on the socket so it won't fall out when you're holding the PCB bottom up to solder the pins, solder all the pins, check for shorts at the soldered socket and insert the chip minding the notch again and you're done.

 

Note that once the 4050 is removed the atari won't produce a picture until the new chip is placed. Since the problem only happens using the 2nd controller button. You might want to wait on doing the repair.

[loggahead]

Update:

 

I just mailed out a check to Best Electronics for a 4050 chip. It was only $0.29 cents! But my min order had to be $15, well I needed a 7800 power supply also, so all is good. Best Elec, said that if the chip doesn't work that it could also be a bad capacitor?

 

Anyhow, thanks for the info on replacing this chip Blinky, I will post a reply when I get the chip and give it a go.

 

-logga

[Blinky]

I just mailed out a check to Best Electronics for a 4050 chip.

 

Did you get a socket with that ?

 

Best Elec, said that if the chip doesn't work that it could also be a bad capacitor?

 

I'm pretty sure the 4050 will work. If it won't then I think that the problem is located somewhere else than in the capacitor.

 

Anyhow, thanks for the info on replacing this chip Blinky, I will post a reply when I get the chip and give it a go.

 

Your welcome.

 

Looking forward to your next post.

[loggahead]

I am not sure what you meant by getting a socket with it. To my knowledge I didn't. Looking at the chip on the board I only need to solder the new one in right?

 

-logga

[Blinky]

I am not sure what you meant by getting a socket with it.

 

By socket I ment a IC socket. So it would be soldered instead of the chip and the chip goes into the socket.

 

Looking at the chip on the board I only need to solder the new one in right?

 

Right.

 

I do prefer soldering the chip too A socket was just handy for future replacements.

[loggahead]

Yeah, it ocurred to me after I posted what you meant. I didn't even know I could do that. doh!? I wish I would have ordered one. You think Radioshack would have a socket that would fit that chip?

 

-logga