30 replies to this topic

[Muddawg]

hey peeps! I got this Darth Vader style Atari, but it only seems to partially work. When i turn it on, i get a play field and stuff, but the sprites apear to be screwed up. Some games have sprites moving horizontally across screen, or to many (like in Combat there are blue tanks horizontally lined up across screen) I know its not my games because I have a heavy sixer and all my games work fine on it. My Atari mother board says it is a revision 16 if that helps. If it can be fixed with sodering I can do that!

Ok

[bjk7382]

I had a system that would do that. There would be a white spot scrolling down the screen and you can see things that shouldn't be there. Like I turned on Kaboom and without playing you could see the bombs falling

I tested the Voltage regulator and found that is was allowing too much power to the system.

I will post a pic of what you should check in a minute

[bjk7382]

When you open it up, you will see a chip like the one shown below. You need to test the three prongs coming off of it. This is the voltage regulator and it needs to be putting out about 5 volts dc. My system that I described earler was putting out about 8 or 8.5 volts. Which is way too much and will draw out wierd effects in the game.

If you can't test it, I would find someone with a multimeter and test it. multimeters are very cheap and very helpful for problems like this.

If it is the VR, you can find them at Radio Shack for like .70 cents. Just give them the little number off the front of it.

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[povlok1]

take a pic of the TV screen for me plz,, maybe I can help

[Muddawg]

ok guy thats really helpful. I dont actually have a multimeter, but my grandparents do. ill get them to bring it next time i see them.

But why would the VR be messed up? is it because it is old? or is it because Atari put the wrong one there in the first place?

[Muddawg]

sorry guy i cant I dont have a digital camera :-(

[bjk7382]

Sometimes if the console is left on for too long it will go bad. It isn't that they put the wrong one in, it is just probly bad.

I will dig out my system with a bad regulator in it and take a picture of the screen.

[bjk7382]

Here are pics of my system with a Voltage regulator that is putting out too much.

the other two pins read around 10 so I know the bottom one should be around 5. Very odd color, and VERY bad sound.

I am surprised it still works.

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[Muddawg]

ya, the color or sound wasn't off, there its ushally to much sprites on screen that shouldn't be there. But thanks a lot I'll try this out ASAP.

[cwilkson]

bjk7382 said:

the other two pins read around 10 so I know the bottom one should be around 5. Very odd color, and VERY bad sound.  

Hrm? Are you sure they both read around 10 volts? In your pic, the top pin should be...above 8 volts, the center pin is ground (=0V), and the bottom pin should be very close to 5V. If that center pin is at 10V, that's your problem.

And Muddawg, power is suspect. But try wiggling the cartridge and see if that affects your weird sprite behavior. You could just be getting a bad contact. Especially with Activision games.

-Chris

[bjk7382]

That is my known bad system anyway, I just take parts that I need for other systems off of it. I am not trying to fix that one in the picture. Although all I think it needs is a Voltage regulator. The top pin measured over 10 and the bottom one reads what you see in the pic. which is, from what i've heard supposed to be somewhere around 5. That is from another thread where one persons read less than 5 and there was no picture or anything.

[cwilkson]

Yah...the 7805 is dead. Get a new one. And don't run the system until you do...you don't want to blow up that precious TIA chip!
-Chris

[bjk7382]

It is in the worst shape anyways (case). I don't really care much about it. I already robbed the RIOT chip out of it. The one inside of it now is from a bad heavy sixer that I fixed with this lite sixer. The button was being read as held down all the time even without a joystick.

So if you need the TIA or the other chip, I will canabalize it for you.

I should have mentioned before that there are two things bad with it the 7805 and the riot.

[Esc]

Just for my future reference, you have the negative black lead (ground) on the centre pin of the voltage regulator, and the positive red pin reading on the 1st and 3rd pins? Both 1st and 3rd pins should give you an approx. of 5 Volts reading on the multimeter?

I've got a somewhat dead Sears Telegames II unit I'd like to check. I don't think its the power supply. I'm getting no picture (just static), although when I do turn it on and off I do seem to see "something" going on the screen. It does power up properly (the Sears has LED indicators for power), any other suggestions I can try in addition to the voltage regulator?

[bjk7382]

My understanding is that the top pin is the voltage coming in which is 9 or 10, and the bottom pin is the voltage going out which should be 5. And the middle one is always ground (black)

[Esc]

So, if the 1st pin isn't reading 9-10V range, and the last pin isn't reading around 5Volts, we can assume the faulty part is this voltage regulator?

[bjk7382]

Esc said:

So, if the 1st pin isn't reading 9-10V range, and the last pin isn't reading around 5Volts, we can assume the faulty part is this voltage regulator?

Correct, as far as I know. There was another thread where someones voltage regulator was doing the opposite of mine. There was no power to the system instaid of too much like mine.

And if it isn't right, they are only like .70 cents, not a costly mistake. And it can't hurt to have a new one.

[Esc]

If someone plugged in the wrong power supply, would this voltage regulator probably get damaged?

[bjk7382]

I think that would be pretty hard, because I have heard that it can handle up to like 30 volts dc or something. but there are no fuses in it so, I would think that voltage reg. would be the first thing to go.

[cwilkson]

Wow...too many posts to try to quote everyone. I'll just sum it up. Here goes!

Yes. middle pine black lead. 9-10 volts and 5 volts.

If the input pin is 9 volts (or higher) and the output is not 5v, the regulator is dead. get a new one.

If the input is lower than about 8.5 volts, then it may be the regulator, the power pack, or the power switch. Try, in order, the following: unplug the powerpack from the 2600 and measure its output. The center pin is positive. If that's ok (9 volts or more) then plug it back in and wiggle the powerswitch while it's turned on. If the voltage at the regulator doesn't change, you could have a bad regulator. Ditch it.

If someone plugged in 30v powersupply, it might blow the regulator. The Atari needs a few hundred milliamps at 5V. Lets say best case, 250mA.
If the input is 30V and the output is 5V, the regulator is dropping 25V. That means the regulator is dissapating 25V*250mA=~6Watts. That's pretty hefty...I don't know how much help you get by using the motherboard as a heatsink.

Bleh.
-Chris

[cwilkson]

Oops...I missed a message.

There are no fuses in the 2600, but the 7805 has builtin current limiting and thermal overload limiting. It really is quite robust. But they're 20+ years old now....who can blame them for dying?

-Chris

[Esc]

Hi guys, I finally got around to testing a Sears Telegames II unit I have. The output voltage coming from the Voltage Regulator is approximately 5Volts, but the input is at around 7.5Volts. Is this OK? I checked my 9Volt 500ma Adapter for it, and it puts out 14Volts on the Voltmeter ? why is that?

Also,are 7805 voltage regulators created equal? I have a spare one that says T12 on it, and i'm wondering if that is a 12V output ? The one on the Atari I believe says "5" somewhere

[cwilkson]

The +5V regulator will say 7805. A 7812 is a +12V regulator.

7.5V coming in is pretty low. If you plug something into the cart port that needs a lot of current, your 5V could dip (because the 7.5V will dip). I'd try to get another wallpack, just in case. The wallpack will have a non-zero output resistance. When you draw current from it, the voltage will drop accordingly. But a meter (should) draw no current. That's why the wallpack voltage is way above 9V when it's only connected to a meter.

-Chris

[Esc]

I swapped out the regulator and the power pack (9v) and i'm getting 5 volts and 8.0 Volts. Is 8 volts too low? What else can I check on this?

[cwilkson]

Esc said:

I swapped out the regulator and the power pack (9v) and i'm getting 5 volts and 8.0 Volts.  Is 8 volts too low?  What else can I check on this?

Ok...8V is at the low end, but it's probably ok.

Are you still having weird sprite problems? If so, it could be any of the 3 main chips. If your chips are socketed, try swapping out the TIA chip with one from your working deck. Be sure to get the orientation right.

-Chris