Pitfall and Frying?

[Benzman66]

Here is another strange issue. Just picked up another 4 switch and while all games work as they should, when you put the Pitfall cart in and turn it on, it sounds like "electrical frying" on the speakers. Definitely not the cart as I tried 4 different ones, also changed the C241, C243, and C242 caps, but nothing. Donkey Kong does it a little, but nothing like Pitfall. Your thoughts?

 

BTW, also swapped out the chips.

Edited September 7, 2010 by Benzman66

[Cliff Friedel]

Here is another strange issue. Just picked up another 4 switch and while all games work as they should, when you put the Pitfall cart in and turn it on, it sounds like "electrical frying" on the speakers. Definitely not the cart as I tried 4 different ones, also changed the C241, C243, and C242 caps, but nothing. Donkey Kong does it a little, but nothing like Pitfall. Your thoughts?

 

BTW, also swapped out the chips.

 

I am not sure how much this will help, but did you check the RF connectors at the atari and at the plug? If they are corroded or the connections aren't good, you could get the sound issues. I would also check the solder points where the RF connects to the Atari. if worst came to worst, you could always clip an RCA cable to the resistor where the A/V mod shows and hook it to a speaker to see if you are getting sound there. Hope this helps.

 

Cliff

[Pioneer4x4]

Here is another strange issue. Just picked up another 4 switch and while all games work as they should, when you put the Pitfall cart in and turn it on, it sounds like "electrical frying" on the speakers. Definitely not the cart as I tried 4 different ones, also changed the C241, C243, and C242 caps, but nothing. Donkey Kong does it a little, but nothing like Pitfall. Your thoughts?

 

BTW, also swapped out the chips.

Pitfall or Pitfall II? If Pitfall II, it could be something with the sound chip in it.

[Benzman66]

It is regular Pitfall and I should mention the sound starts after the reset/start game is made.

[Benzman66]

Here is some more interesting info. I notice that when the aluminum cover is removed, the buzzing is still there, but gets louder when the cover is put back on.

[mbd30]

Man, I though this thread would be about some cool glitch that resulted from "frying" the 2600.

[A.J. Franzman]

I notice that when the aluminum cover is removed, the buzzing is still there, but gets louder when the cover is put back on.

What aluminum cover? If you mean the RF shielding on the motherboard, 4-switchers don't have aluminum. It's steel -- possibly an alloy known as mu-metal, but Atari were such tightwads, I doubt they'd pay the extra cost for that luxury.

[Dr Manhattan]

I used to play Pitfall all the time when I was frying. That is until things got a little too intense for me.

 

But seriously folks, I had the same problem as the OP with one of my ColecoVision systems. I never figured out the cause.

[Benzman66]

Yep A.J.

The steel cover.

 

Anyhow, I noticed that the snap/crackling stops when the cover is totally removed after a minute or two, but when replaced, it starts the noise again.

[Th3_uN1Qu3]

It's probably digital noise from the CPU getting into the RF modulator and into your TV speakers. Do you notice any effect on the picture as well? If not, it's probably not getting into the modulator but maybe the sound chip itself. The shielding is needed so that the CPU and RF modulator don't affect nearby equipment, or are not affected by outside equipment themselves. However, shielding an entire assembly without using separator walls can (and will) make the various parts inside radiate upon each other.

 

I used to have an old TV with a miscalibrated tuner. After a lot of trial and error i managed to fix the tuner, however i did the calibration with its shield walls off, and when replacing them, the thing would malfunction again. From that day on, the set ran without shields on its tuner and it worked just fine. That is till my grandparents decided to toss it and buy a new one, because the old one wouldn't receive all cable channels.

 

I see Pitfall is a pretty impressive game by 2600 standards (too bad it's not on any of my carts), it probably taxes the CPU a lot, so its processing noise enters other circuits.

Edited September 14, 2010 by Th3_uN1Qu3

[AtariLeaf]

It's probably digital noise from the CPU getting into the RF modulator and into your TV speakers. Do you notice any effect on the picture as well? If not, it's probably not getting into the modulator but maybe the sound chip itself. The shielding is needed so that the CPU and RF modulator don't affect nearby equipment, or are not affected by outside equipment themselves. However, shielding an entire assembly without using separator walls can (and will) make the various parts inside radiate upon each other.

 

I used to have an old TV with a miscalibrated tuner. After a lot of trial and error i managed to fix the tuner, however i did the calibration with its shield walls off, and when replacing them, the thing would malfunction again. From that day on, the set ran without shields on its tuner and it worked just fine. That is till my grandparents decided to toss it and buy a new one, because the old one wouldn't receive all cable channels.

 

I see Pitfall is a pretty impressive game by 2600 standards (too bad it's not on any of my carts), it probably taxes the CPU a lot, so its processing noise enters other circuits.

 

This may well be but it doesn't explain why it only happens with pitfall carts. I have 3 different machines (one six switch and 2 vaders) and 5 different pitfall carts all give the same electric crackling sound as the OP describes, but are fine with other carts, including other activision carts like Pitfall II.

 

EDIT - I should say it doesn't happen with my sears heavy sixer but if it is a shielding issue, again, why only pitfall carts?

Edited May 18, 2014 by AtariLeaf

[retrogoober]

I have this same issue with all pitfall carts on a 2600 junior! I've learned to love me some crackle when playing Pitfall:)