1.19MHz is not for the RTC. And the ticket is already fixed 😉

The 1.19 MHz oscillator is probably for something other than the date/clock.

PCBONEZ - I am not quite sure what you are asking. The issue has been resolved. The 32.768 KHz crystal on the board had gone bad. I've replaced it and the system works fine now.

feipoa wrote:

The 32.768 KHz crystal on the board had gone bad. I've replaced it and the system works fine now.

AWESOME!
Glad it's fixed!
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That's good to know. I guess maybe the oscillator was washed out with acid from the original battery? I think mine was a bit dull looking, implying it had been eaten by the acid. Perhaps the problem would disappear if I replaced it and it is such an easy job I will have to give it a try at some stage. I suppose it is possible, if the corrosion broke past the seal on the bottom of the can.

Note to self:
If you give up on and trash a mobo - save the crystals!

At about 12 hours later with the system turned off, the time has drifted about 1hr 30 min. This could be due to,

a) the series cermaic capacitor needs replacement. It has 27J written on it, which I assume is 27 pF.
b) the replacement crystal has some drift in it, it was a desoldered piece
c) the 3V coin cell battery is insufficient.

I suspect c) is the most likely culprit. Does anyone know of any CR2032 battery holders (DIP) which will hold two CR2032 batteries in series? I do not want to mount some external battery holder with wires. Actually, this might be a good question for a new thread. Coin cell battery holder for holding 2 series CR2032 batteries

I agree. 4.5V is generally considered what you need to hold the CMOS settings reliably.

I also replaced the series 27 pF capacitor, however after doing so, the system was off by a factor of 5 again. I think the heat of the soldering iron on the crystal's pin must be jeapordising the cyrstals. I replaced the crystal again with another desolder, and it is counting normally again.

I find that even 3 V is fine to hold the CMOS settings. The issue only seems to be with the date clock.

I haven't had to replace a lot of crystals.
Perhaps using soldering heatsinks like when soldering those old 3-leg transistors and such is a good idea for crystals too.
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