How about copying the contents of the old nvram to the new one?
----- Original Message -----
From: "David C. Partridge" <[email protected]>
To: "'Discussion of precise voltage measurement'" <[email protected]>
Sent: Thursday, November 02, 2017 2:58 PM
Subject: Re: [volt-nuts] Prema 6048 Cal switch confusion
Update - when I tried this I was using a brand new DS1220AD-100IND (blank)
to replace the DS1220Y.
Reinstalling the DS1220Y and it worked as expected! Processor must detect
cal mode by writing to NVRAM - if succeeds, then in Cal mode??? Maybe
Is there some obscure incompatability between the DS1220AD and the
DS1220Y???
Dave
-----Original Message-----
From: volt-nuts [mailto:[email protected]] On Behalf Of David C.
Partridge
Sent: 02 November 2017 18:23
To: 'Discussion of precise voltage measurement'
Subject: [volt-nuts] Prema 6048 Cal switch confusion
I've got a Perma 6048 that I've trying to put into Cal mode. It just
won't!
The switch on the rear panel works OK, AFAICT when in the Cal position it
connects ~WE on the DS1220 (pin 21) and ~W on the $864 SRAM (pin 27) to a
4K7 pullup to +5V and to the output of an LS00 which should be strobing
the
Write lines low as needed. I can't see any way in which the processor
can
be informed of the switch setting! In measure mode it just connects ~WE
on the DS1220 to a 10k pullup to +5V.
The schematic is on page 120 (Figure 11.4) of the user manual and also
page
9-7 of the service manual.
Clearly I'm missing something - as a friend reports that his does go into
cal mode.
Confused ...
Thanks
Dave
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