[time-nuts] PM6681 PROMs v109

[ew]

On 11/13/2020 2:21 PM, ew via time-nuts wrote:
> Having contacted several time nuts off list to cut down traffic but no response will some one tell me the battery number  covered   and number of cells so I am properly prepared to exchange.

Bert

The backup battery really has nothing to do with the PROMs (Subject of 
this thread). It backs up, when the counter has no AC power, a section 
of SRAM memory. That memory holds a calibration constant that affects 
the accuracy of the counter's interpolation method for measurements. 
This memory also holds more mundane things like save and recall of 
counter user setups.

The backup battery is a single standard CR2032-style lithium 3V coin 
cell. To open the case there are 3 torx head screws. One in the bottom 
center (T10 size) and two at the back plastic feet (T20 size). I started 
the opening process by prying with a small screwdriver in the cracks 
between the plastic front panel and the case.

To keep the RAM memory intact, the counter must have AC applied and be 
in Standby. To remove the battery the holder has openings toward the 
front of the counter where you gently pry up the battery. I used a 
plastic screw driver adjustment tool. The new battery easily slides in 
the way the old one came out. For maximum long term goodness avoid 
touching the new cell with bare hands (possibly a bit too anal-retentive).

Hopefully a small pic I took of the battery location will be attached.

-Rex


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