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Atari 800 XL black screen

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I think I got it. It's either the ROM or the socket. I noticed the ROM tests are failing (red bars) when it starts acting up.

I cleaned the pins and re-seated it but at an angle in the socket and so far so good.

 

** just swapped out the socket and i noticed the originals are those crappy ones with the metal tabs only on the insides so it doesn't grab the chip pins from both sides

 

Edited by sideburn
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I think we are good to go now!

I cleaned all the pins on the ROM, swapped out the socket, dexoxited al the other sockets, rinsed the board in isopropyl, and blew it dry with an air gun.

You can't even tell I swapped out the socket :)

 

IMG_1275.thumb.jpeg.d5c17efb3d524788e3dc084d230507ac.jpegIMG_1273.thumb.jpeg.3309f84a8bd155114cb3a056bd482159.jpeg

 

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4 hours ago, sideburn said:

 

** just swapped out the socket and i noticed the originals are those crappy ones with the metal tabs only on the insides so it doesn't grab the chip pins from both sides

 

@sideburn  Great, good job. :grin:

 

Yup, those sockets are commonplace on those socketed A8 boards.

 

They aren't the best and they are called single wipe sockets.

 

Double or dual wipe, (metal on both sides) are better and then you have the precision round or turned socket types.

 

Double/Dual wipe: 

image.png.e056c0b356bbbeb351adaf20d62256cc.png

 

Precision round/turned: 

image.png.950411c6bd59063df42e026d61fd6103.png

 

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12 minutes ago, Beeblebrox said:

@sideburn  Great, good job. :grin:

 

Yup, those sockets are commonplace on those socketed A8 boards.

 

They aren't the best and they are called single wipe sockets.

 

Double or dual wipe, (metal on both sides) are better and then you have the precision round or turned socket types.

 

Double/Dual wipe: 

image.png.e056c0b356bbbeb351adaf20d62256cc.png

 

Precision round/turned: 

image.png.950411c6bd59063df42e026d61fd6103.png

 

Ahh didn’t know the names. Dual wipe installed. Still going strong  

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I have just finished getting an 800XL back into operation (ALMOST). I had everything working after doing a SV 2.1 mod. Keyboard worked perfectly, had good video with only faint vertical bars. After putting it back together, I have no video, just a black screen.  The computer makes the boot noise, I get keyboard clicks, and audio with game carts.  I took it apart back down to the bare MB. Still no video, swapped out the major chips and the 4050, still no video.  What are my possibilities.  I don't have an O scope and my trouble shooting is restricted to a multimeter and replacing parts.

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17 minutes ago, hueyjones70 said:

I have just finished getting an 800XL back into operation (ALMOST). I had everything working after doing a SV 2.1 mod. Keyboard worked perfectly, had good video with only faint vertical bars. After putting it back together, I have no video, just a black screen.  The computer makes the boot noise, I get keyboard clicks, and audio with game carts.  I took it apart back down to the bare MB. Still no video, swapped out the major chips and the 4050, still no video.  What are my possibilities.  I don't have an O scope and my trouble shooting is restricted to a multimeter and replacing parts.

Did you check all the chips for continuity. Put one lead on the pins on the chip and then the other lead on the solder connection on the other side of the board. The problem with my black screen issue was ram and bad connections with the chip because the stock sockets are pretty crappy. 

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1 hour ago, hueyjones70 said:

I have just finished getting an 800XL back into operation (ALMOST). I had everything working after doing a SV 2.1 mod. Keyboard worked perfectly, had good video with only faint vertical bars. After putting it back together, I have no video, just a black screen.  The computer makes the boot noise, I get keyboard clicks, and audio with game carts.  I took it apart back down to the bare MB. Still no video, swapped out the major chips and the 4050, still no video.  What are my possibilities.  I don't have an O scope and my trouble shooting is restricted to a multimeter and replacing parts.

So your computer  appears to having normal booting and keyboard clicks….right?

 

Insert a game and see if you can confirm the sound is there. If all appears to be normal.

 

your problem may be your vedeo cable or your tv, I would try connecting through RF or a different video cable -Tv combination 

 

 

 

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I think the problem was with some old solder joints.  I touched up the joints on the DIN connector and all of the resistors in the area of the 4050 and when I hooked it up again, all was working.

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19 hours ago, hueyjones70 said:

I think the problem was with some old solder joints.  I touched up the joints on the DIN connector and all of the resistors in the area of the 4050 and when I hooked it up again, all was working.

Great, always as good feeling when the things finally come up alive again! 

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Wanted to drop a thanks into this thread.  I picked up an 800xl on eBay while enjoying an adult beverage recently (don't drink and eBay!) and finally got it up and running.  It would instantly drop to RAM test on power up, which was a good sign.  I pulled all 8 MT RAM ICs via a hot air station and added some vintage red sockets I found at Edgar's Digital in Las Cruces, NM.  I swapped out the MT 4264-15 with some TI 4164-120 that I had in inventory, all seemed to come back to life and it was pretty amazing.

 

I tested all 8 MT RAM ICs one at a time, the RAM check failed on 5 of them.  Photos of various different RAM failure modes are on twitter if you want to see what it looked like in the end. 

 

 

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