Author Topic: Solartron LM1619 Digital Volt Meter (with nixies!)  (Read 3360 times)

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Offline dexters_lab

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Solartron LM1619 Digital Volt Meter (with nixies!)
« on: October 14, 2015, 08:27:13 am »
Did a teardown on a solartron lm1619 digital volt meter the other day, thought some of you might like to see.

dates from the early 1970 from what i can gather.


Offline edpalmer42

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Re: Solartron LM1619 Digital Volt Meter (with nixies!)
« Reply #1 on: October 14, 2015, 05:19:12 pm »
The BTY>14V setting is probably to check the voltage of the internal battery.

Do you know the purpose of the standard cell?  After this many years, the cell is probably dead and yet the unit seems to be working properly so the cell can't be part of the measurement process. 

Ed
 

Online Andy Watson

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Re: Solartron LM1619 Digital Volt Meter (with nixies!)
« Reply #2 on: October 14, 2015, 05:37:15 pm »
When I started work, sometime in the 1980s, we had the DC only version of this meter. It was the only half-decent bit of kit that we had! The "Cal" position measures the voltage on the standard-cell and there's the screwdriver adjustment to bring it into alignment. I had always assumed that the standard was some sort of compensated zener (or such like) - never dreamed that they would put a standard cell in the unit! 
 

Offline Macbeth

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Re: Solartron LM1619 Digital Volt Meter (with nixies!)
« Reply #3 on: October 14, 2015, 06:09:06 pm »
Aha, so CAL10185 means set it to 1.0185 volts!

I never would have believed an actual Weston cell would be used as an internal reference.
 

Offline dexters_lab

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Re: Solartron LM1619 Digital Volt Meter (with nixies!)
« Reply #4 on: October 14, 2015, 07:05:10 pm »
i had a quick look at it today, if i adjust the cal on the solartron against my bench PSU and my bench meter and switch back to the cal range on the solartron the value is 1.017 so i guess the cell is past its best

i also noticed today the AC ranges are completely dead :--

i am tempted to hack this into a nixie clock, or would that be wrong?

Offline edpalmer42

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Re: Solartron LM1619 Digital Volt Meter (with nixies!)
« Reply #5 on: October 14, 2015, 07:11:18 pm »
Aha, so CAL10185 means set it to 1.0185 volts!

Sounds likely, but that's confusing for a couple of reasons.  First, the meter can't display 1.0185.  Second, since there's no temperature control it's going to be an unsaturated cell.  They have voltages in the 1V019x range.  EOL is considered to be 1V0183 according to NBS Monograph 84.

Ed
 

Offline dexters_lab

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Re: Solartron LM1619 Digital Volt Meter (with nixies!)
« Reply #6 on: October 14, 2015, 07:22:36 pm »
Aha, so CAL10185 means set it to 1.0185 volts!

Sounds likely, but that's confusing for a couple of reasons.  First, the meter can't display 1.0185.  Second, since there's no temperature control it's going to be an unsaturated cell.  They have voltages in the 1V019x range.  EOL is considered to be 1V0183 according to NBS Monograph 84.

Ed

i guess it would have been explained in the user guide and there was probably a recommended time period to change the cell

i am looking for a user guide/service manual, if anyone sees one, let me know!


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