Tektronix TDS3000B RTC running slow

[perdrix]

I know it's not a major issue, but has anyone hit this problem and found a resolution?

I suspect it's probably a trimmer or firmware controlled varicap that needs tweaking, but ...

TIA David

[voltsandjolts]

The RTC is a sealed DIP module by Dallas/Maxim with internal battery and some NVRAM in it too.
The battery in your module is likely failing.
Some folks have hacked them open and replaced the battery.
Otherwise you need to source a new one...which is a bit of fun because there are lots of fakes around.
The bad news is they are soldered into the main board, I added a socket when I changed mine out.
The good news is there is no critical info in the NVRAM, so you can just fit a new blank one. IIRC the operating hours gets reset to zero.

https://www.eevblog.com/forum/testgear/tek-tds3000-series-and-dallas-nvram/
https://www.digikey.co.uk/product-detail/en/maxim-integrated/DS1742W-150/DS1742W-150-ND/951280
https://www.ebay.co.uk/sch/ds1742w