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GRiDCASE 2 - Dallas Chip

A

Atomtan

Member
Joined
Feb 9, 2011
Messages
34
Location
Leicester, UK
Hi Folks - bit of a long shot but I suspect my previously working machine has stopped booting due to the Dallas Chip finally expiring. I dissembled the machine so far, but realised to get to that chip on the lower board, it will mean a deeper tear down which I am happy to do, but only when I have a worked out option on my desk to replace the Dallas. I see two options, the grind the side off the Dallas and modify the chip or potentially replace it with a modern button cell replacement (the option I prefer). I can get these replacement chips in the UK, but there seem to be different ones depending upon which Dallas is in the machine. On a long shot, I wondered if anyone knows which Dallas model it is in this machine? - Thank you for any guidance you can give.
 
I would suggest you disassemble it further to confirm it even has a Dallas RTC and not just a 3.6V battery soldered to the board. In my experience the most models did not have a Dallas RTC. So far I've not yet come across one, none of the 6 gridcases I've worked on had one.
 
Atomtan said:
Hi Folks - bit of a long shot but I suspect my previously working machine has stopped booting due to the Dallas Chip finally expiring. I dissembled the machine so far, but realised to get to that chip on the lower board, it will mean a deeper tear down which I am happy to do, but only when I have a worked out option on my desk to replace the Dallas. I see two options, the grind the side off the Dallas and modify the chip or potentially replace it with a modern button cell replacement (the option I prefer). I can get these replacement chips in the UK, but there seem to be different ones depending upon which Dallas is in the machine. On a long shot, I wondered if anyone knows which Dallas model it is in this machine? - Thank you for any guidance you can give.
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Hello there.
I've been away for a while. I on a break from my studies and had a quick window to check in. I hope to be much more active in the summer months.
But to answer your question, and assuming you haven't torn in to the Grid already, Grid had two versions of a Real Time Clock. The majority of versions have the Dallas DS1287A RTC chip. The chip itself has a BR1225 button cell sealed inside the chip.
Later versions of the 1520 (my motherboard is 'Rev AE') have a Motorola MC146818AP wired to a lithium battery near the RAM.
Getting a replacement DS1287A is risky. Dallas Semiconductor stopped producing these chips in the late 90's. If you find a replacement, it was probably made in the same time frame.
Disassembly of a Grid isn't too difficult. Remove the two plastic "feet" at the rear of the laptop. You will see a screw under the "feet". Remove the screws, slide the lid back, lift, and you're in!
Good luck,
-Shawn
 
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