Libretto: Bad CMOS memory?

[Kazy]

So I'm trying to get a Libretto 70CT back up and running, but after waiting over a month to get a replacement CMOS/RTC battery from overseas. I've tried two different batteries, but neither of them let it keep the time. I've tried reflowing the connector to the board just in case it was a bad solder joint, but the issue still persists.

Is it possible that the CMOS memory itself is bad, or have I just got two bunk batteries? The later one tested at 2.6V, but I haven't tested the first one.

 

[GiGaBiTe]

Did the new batteries come with a pigtail, or did you reuse the existing one? If you reused the existing one, the leaked electrolyte has a tenancy to wick down the inside of the wire and corrode all of the copper, causing high resistance. I recently repaired a 50CT that I had to make a new pigtail for the CMOS battery pack because both the wire and the connector were corroded.

The battery pack should ideally be 2.4v if it has two NiMH/NiCD cells. You may want to load test the battery to see if it can hold that voltage or if it falls flat on its face.

Another thing is you may also need a good main battery. The 50CT I had would behave strangely with a low/dead main battery, even if the CMOS battery was good.

 

[Kazy]

They came with the pigtail. I tested them and they seemed to have good voltage.

The battery has enough charge to keep the thing powered for a few minutes, so it's not completely dead, but it is on its last legs.

 

[GiGaBiTe]

The main battery pack isn't terribly difficult to open and replace the cells, but getting the pack apart in the least destructive manner so it can go back together is difficult.