Replacing or Repairing A1 chip on 5200 (CD4050BCN)

[dino999]

Atari 5200 2-port

-Black screen when system turns on

-Power light remains on even when pressing power button (power adapter must be unplugged to power down)

-All chips except the A26, CD4013, test fine at around 5V. The CD4013 runs at around 10.455V maybe 10.6V (it depends how I situate test probe)

 

 

On page 4A-2 of the field service manual, it states I should test A2 pin 40. I put my ground lead on pin 1 and the red on 40. It read around 0V.

The guide says I have a defective A1 chip. It then says I can repair or replace it before re-testing all the chips.

 

How do I repair the chip?

Edited November 12, 2015 by dino999

[fiddlepaddle]

With a really tiny soldering iron and a pile of nand gates?

[dino999]

It may be repairable but the guide does not detail the process.

 

Can anyone confirm this is a valid replacement for the A1 chip in the 2-port 5200?

http://www.ebay.com/itm/251907497044

 

I am unsure how to read these chips. I just typed CD4050BCN in the search and found this one for sale. The full designation I see on my chip is:

+I8302 <--That's the letter I as in igloo after the plus symbol

CD4050BCN

MM5650BN

 

I don't know whether the other lines are superfluous are actually are important when seeking a replacement chip.

[zylon]

That should be a direct replacement. As for the 4013, that one splits the power into the two circuits: logic + video. It seems your video is turning on, but not the logic side.

[dino999]

That should be a direct replacement. As for the 4013, that one splits the power into the two circuits: logic + video. It seems your video is turning on, but not the logic side.

Thank you for confirming this.

 

Regarding the CD4013, I've read threads that state the power state being stuck to ON wasn't a big issue and that I shouldn't have to replace it. Are you saying I should replace the CD4013 as well?

[zylon]

Thank you for confirming this.

 

Regarding the CD4013, I've read threads that state the power state being stuck to ON wasn't a big issue and that I shouldn't have to replace it. Are you saying I should replace the CD4013 as well?

 

You posted previously that you're getting a black screen. If the system does not read a game, then the logic is not functioning. Or, are you just testing power-up without a game inserted then?

[dino999]

When testing voltage of the chips, I insert a game, but I do not hook it up to a TV. When hooked up to the TV with a game inserted, I get a black screen and no sound.

Edited November 17, 2015 by dino999

[dino999]

 

You posted previously that you're getting a black screen. If the system does not read a game, then the logic is not functioning. Or, are you just testing power-up without a game inserted then?

Also, not recently, but when I tested without a game, all the RAM read as 0v. I am assumed this was normal as the game ROM was not loaded into memory.

[dino999]

Bumping up. Any update on confirming replacement of the CD4013 is absolutely necessary?

[zylon]

you might have to if the logic functions do not power up. black screen is almost always from a bad IC and the 4013 is the starting point. You can avoid it if you can confirm that both circuits it handles are powering up.