Reply 40 of 98, by Deunan
jnemo2004 wrote on 2024-02-15, 13:05:Under RTC , motherboard looks also OK.
Yes, that was just a shadow on the previous photo.
jnemo2004 wrote on 2024-02-15, 13:05:My following steps in this next weekend is to remove all ICs in sockets , check them externally and put in all socket contact cleaner .
That's a good idea. This type of socket can develop poor contact sometimes. You can try standing the mobo upright and testing with ohm meter the RTC chip pin on one side and the soldering below the socket on the other side. Each pin should have good connection (< 1 ohm).
I can see the mobo markings saying MC146818A, so in fact they suggest -A version, as expected for chipset integrated into a couple of large chips. I wonder if your HM6818P is a replacement already? Maybe it's broken after all. If you don't have another mobo to swap the chip try looking for a cheap offer on ebay or something. There isn't any functional difference between 6818 and 6818A, it's just that A version has improved power draw and is easier on the battery.
jnemo2004 wrote on 2024-02-15, 13:05:Also I will do a test with the two BIOS dumps available in this motherboard:
In BIOS Even is equivalent to LO? and Odd to HI?
Yes, that how it usually is. I've seen some cases where LO and HI were reversed for some reason but even if you put the chips in the wrong order nothing will break. The mobo just won't POST with incorrect BIOS data.