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Hello Sprinter friends,
I still have problems with the CMOS RAM DS12887. Every now and then the CMOS RAM loses the BIOS settings. I tested different types. DS 12887, DS 12887A, DS 12887+, DS 12C887. I built another Sprinter. Again, the same phenomenon?
Anyone have a tip?
Regards

Yes, sometimes it's reset itself on my Sp2000 - not know why yet
Good thing time is staying
But shift coordinates of the screen are needed to be setup again from time to time

Shaos, thanks for replay.
I tested a Bechmarq bq32887 CMOS. This one has never forgotten its contents!
I got the DS12887+ new from CN. With 3 pieces the battery was already empty. So here too conversion to external battery.

I have a hint about the problem of data loss in CMOS RAM. Data loss does not occur if Fex Navigator (FN) is exited before power off.
The FN constantly accesses the CMOS (signal play on AS, DS, R/W).
When the FN is terminated, no access to the CMOS can be seen.
The signal play in connection with switching off must probably trigger an erasure process in the RAM.
The problem can also be aggravated by the chip select being permanently on GND.
Does it make sense to change the circuit diagram here?

Interesting