[volt-nuts] Solartron 7071 vs 7081

David C. Partridge david.partridge at perdrix.co.uk
Thu Apr 5 08:07:47 UTC 2012

I just got an email from my contact who checked with the one of the 
members of the service team ...

>However, I checked with the service guy here who does most of the
>DVM repairs and he tells me the only difference is, as you suspected,
>a link on one of the earthy logic boards, board 14 (or board 4 on older
>models). There are a pair of solder pads next to SK414. LK17 is shorted
>to make the instrument think it is a 7071. These links may not be present
>on older models where the link was hard wired. In any event the object
>is to make pin 2 of IC424 low for 7071, high for 7081.
>This line is read on power up.
>The drawings we've got here show this line connected to the "interface"
>section on the back panel GPIB selection switch and indeed on the
>prototype models it was, which meant they could be switched from 7071
>to 81 by flicking this switch. This line was isolated from the switch
>on production models. 

So if you have a 7071, you actually have a 7081 with a not so good zener
and different labels on the keyboard!


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