[volt-nuts] Solartron 7061 help request (eeprom?) (Fred Schneider)

fabioeb at quipo.it fabioeb at quipo.it
Tue Feb 28 10:05:57 UTC 2012

Hello Bill, thank you for the answers.
This morning I swapped the original eeprom with a spare one,
I tried calibrate 0.1V to 100V, so the new constant is
stored during calibration and not hitting "refresh"?
This is confirmed by the fact that it retained the new
values even after power down without the "refresh" command.
So Fred's problem of losing costants should be due to faulty
eeprom? Also my instrument can have a faulty eeprom and have
lost costants during use?

A pair of things, easy to discover that can help somebody else
searching info like me:
- cal key: I don't have the key and the switch is easily tampered
but I don't want to break it. Here are the connections on the
pin header connected to the cal switch:
cal off: connect Blue to Green, just put a jumper on the first
two pins on the header
cal on: connect Yellow to Green and Brown to Red two jumpers
on the pins 2-3 and 5-6

- Ram memory: the capacitor makes it retain data also after power
down and without backup battery for some time, the voltage is as follow:
from 4.4V to 2V in 40s
to 1V in 1m 40s
to 0,5V in 2' 30s
the memory retains data also when it's only at 1V.


Bill Ezell <wje at quackers.net> ha scritto:

> I have several 7061's and 7081's. They're both excellent meters and  
> tend to hold calibration for a long time. My 7081 easily stays  
> within a few ppm/year. (checked against my Fluke-calibrated Datron  
> 4910's)
> In answer to a few of the questions recently asked:
> The battery is only for backing up stored readings and settings. The  
> calibration values are in the eeprom, twice. So, unless it fails,  
> you won't lose the calibration factors. The purpose of the eeprom  
> refresh is just to do an read/erase/rewrite cycle. It was apparently  
> a concern that eeproms of that vintage wouldn't store values over  
> long times (years) reliably. I've not done a refresh on any of my  
> 7061's and haven't had a problem.
> As for heat, the 7061's do run very hot, but that's how they were  
> designed. Not a good idea to put things on top of them without any  
> airspace, though. The hottest area in a properly working 7061 is a  
> small metal-shield box. It has some rather power-hungry IC's (74s  
> series) in it, and it gets too hot to touch. Every 7061 I've ever  
> seen is like that, so I assume it's operating as intended.
> I wouldn't say the transformer runs hot in particular. If you're  
> really seeing that, it's possible you have leaky caps in the power  
> supply, although they'd have to leak a lot without exploding to  
> raise the current drain enough to overheat the transformer. More  
> likely is that it's a ventilation problem. Does your 7061 still have  
> its feet to give it some airspace at the bottom?
> -- 
> Bill Ezell
> ----------
> They said 'Windows or better'
> so I used Linux.
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