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Black Screen issue with Colecovision

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I meant the SRAM, sorry for the confusion. I will try the U4 chip first, and then see what happens. Hopefully I can get this done in the next few days.I will update you when that's done hopefully with some good news. Thanks!!

Thanks

I replaced the U4 SRAM chip with no change. I am going to change out the U3 chip next.It will probably be later in the week before I have time to do this.

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Well, U3 isn't on the bad data line, so I wouldn't be so quick to swap it out. Turn your attention to U18 and U19 next. At the least, pull the chips and see if a short to ground still exists on the dead data line as seen in post 67.

Edited by ChildOfCv

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No, we're only looking for one that causes a short on that data line. And we only have the process of elimination with current equipment.

 

I'd pull player 1's first I guess though. Then see if you still see a short to ground. Then try player 2 without putting player 1 back yet.

 

In fact, I'd leave out any chip I pull until the one that eliminates the short is found. Then they can be restored one by one, still making sure the short isn't back.

Edited by ChildOfCv

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I finally got back to this. I apologize for the big gaps right now, but my son plays college baseball so during the season I don't have as much free time. I replaced controller chip for player 1 with no change. I have it socketed so I can pull it easily. What is the best location to check with the logic probe to check for the short to ground. I will busy for a couple more weeks and then I should be able to get back at it a little more frequently. Thanks

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I finally got back to this. I apologize for the big gaps right now, but my son plays college baseball so during the season I don't have as much free time. I replaced controller chip for player 1 with no change. I have it socketed so I can pull it easily. What is the best location to check with the logic probe to check for the short to ground. I will busy for a couple more weeks and then I should be able to get back at it a little more frequently. Thanks

The logic probe can't tell you about shorts. Not part of its mission statement.

 

To check for a short, turn off the power and use the multimeter in diode mode. If you see a low voltage, you have a short. You may also be able to get a reading in ohm mode. You'd be checking any of the locations in the picture in post #67.

Edited by ChildOfCv

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