diagnosing an Intel Series II MDS monitor failure

Eric Smith spacewar at gmail.com
Sat Aug 1 19:43:53 CDT 2015

On Sat, Aug 1, 2015 at 5:52 PM, dwight <dkelvey at hotmail.com> wrote:
> There we two different reference voltages on 723s. I don't recall which
> was which but one had to change the feedback resistors if you used the
> wrong one.

There's a reference with a built-in current source and amplifier,
which outputs on pin 6 on the DIP. That's the one that's specified as
7.15V ±0.35V.

The 723 in DIP also has a 6.2V zener diode in series from the
regulator output. It's not bonded out in the metal can package.

I've never found a 723 datasheet that gives a different values for
either reference.

The 9.4V that I'm getting from Vref, which is tied to the amplifier
IN+, exceeds the absolute maximum rating for the amplifier input,
which is 8.0V or 8.5V depending on the vendor.

The modern 723 datasheets seem to be dumbed down from the original
ones, with some useful information removed.  :-(

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